san francisco earthquake 1989 case study

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San Francisco Earthquake of 1989

By: Editors

Updated: September 11, 2018 | Original: December 18, 2009

Loma Prieta, California, Earthquake October 17, 1989, Structures Damaged In The Marina District Of San Francisco, The First Story Of This Three-Story Building Was Damaged Because Of Liquefaction; The Second Story Collapsed, What Is Seen Is The Third Story.

On October 17, 1989, a magnitude 6.9 earthquake hit the San Francisco Bay Area, killing 67 people and causing more than $5 billion in damages. Despite the fact that the disaster was one of the most powerful and destructive quakes ever to hit a populated area of the United States, the death toll was relatively small. The disaster is known as both as the San Francisco-Oakland earthquake and the Loma Prieta earthquake because it was centered near Loma Prieta Peak in the Santa Cruz Mountains.

On October 17, the Bay Area was buzzing about baseball. The Oakland Athletics and San Francisco Giants, both local teams, had reached the World Series. The third game of the series was scheduled to begin at 5:30 p.m. at San Francisco’s Candlestick Park. Just prior to the game, at 5:04 p.m., with live cameras on the field, a magnitude 6.9 quake rocked the San Francisco Bay region. The quake was centered near Loma Prieta Peak (approximately 60 miles south of San Francisco) in the Santa Cruz Mountains. Though the stadium withstood the shaking, other parts of the Bay Area were not as fortunate. Sixty-seven people perished as a result of the quake, which lasted around 15 seconds, while more than 3,000 others were injured.

Did you know? The San Francisco-Oakland Bay Bridge opened to traffic in November 1936, six months before the Golden Gate Bridge.

San Francisco’s Marina district suffered extensive damage. Built on an area where there was no underlying bedrock, the liquefaction of the ground resulted in the collapse of a number of structures. Additionally, gas mains and pipes burst, sparking fires. A 1.25-mile segment of the two-level Cypress Street Viaduct along the Nimitz Freeway (Interstate 880), just south of the San Francisco-Oakland Bay Bridge, collapsed during the quake, resulting in 42 fatalities when the upper level of the road crashed onto the cars on the lower level. One person was killed when a portion of the upper deck of the Bay Bridge–which had been scheduled for a retrofitting the following week—collapsed onto the lower level.

Another hard-hit area was Watsonville, located several miles from the quake’s epicenter. More than 30 percent of Watsonville’s downtown and 1 in 8 houses were destroyed.Total damages from the earthquake were estimated at more than $5 billion. In the quake’s aftermath, San Francisco and other communities enacted strict regulations requiring unreinforced masonry buildings to be retrofitted.

san francisco earthquake 1989 case study

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Loma Prieta Earthquake Professional Papers Completed

The four Loma Prieta Earthquake Professional Papers, which were published as multiple chapters, comprehensively document the magnitude 6.9 earthquake in California that shook the San Francisco and Monterey Bay regions on October 17, 1989. They contain almost 3000 pages written by 401 investigators of the earthquake. The investigations were funded by a special Congressional appropriation to the U.S. Geological Survey and National Science Foundation after the earthquake to improve understanding of both the complexity of earthquakes and how society can reduce losses in future earthquakes. PDF’s of individual chapters can be downloaded by clicking on the appropriate professional paper below. Paper copies can be purchased at

Professional Paper 1550 – Earthquake Occurrence

William H. Bakun and William H. Prescott, editors

Professional Paper 1550  seeks to understand the M6.9 Loma Prieta earthquake itself. It examines how the fault that generated the earthquake ruptured, searches for and evaluates precursors that may have indicated an earthquake was coming, reviews forecasts of the earthquake, and describes the geology of the earthquake area and the crustal forces that affect this geology. Some significant findings were:

  • Slip during the earthquake occurred on 35 km of fault at depths ranging from 7 to 20 km. Maximum slip was approximately 2.3 m. The earthquake may not have released all of the strain stored in rocks next to the fault and indicates a potential for another damaging earthquake in the Santa Cruz Mountains in the near future may still exist.
  • The earthquake involved a large amount of uplift on a dipping fault plane. Pre-earthquake conventional wisdom was that large earthquakes in the Bay area occurred as horizontal displacements on predominantly vertical faults.
  • The fault segment that ruptured approximately coincided with a fault segment identified in 1988 as having a 30% probability of generating a M7 earthquake in the next 30 years. This was one of more than 20 relevant earthquake forecasts made in the 83 years before the earthquake.
  • Calculations show that the Loma Prieta earthquake changed stresses on nearby faults in the Bay area. In particular, the earthquake reduced stresses on the Hayward Fault which decreased the frequency of small earthquakes on it.
  • Geological and geophysical mapping indicate that, although the San Andreas Fault can be mapped as a through going fault in the epicentral region, the southwest dipping Loma Prieta rupture surface is a separate fault strand and one of several along this part of the San Andreas that may be capable of generating earthquakes.

Professional Paper 1551 - Strong ground motion and ground failure

Thomas L. Holzer, editor

Cover image for Professional Paper 1551.

Professional Paper 1551  describes the effects at the land surface caused by the Loma Prieta earthquake. These effects: include the pattern and characteristics of strong ground shaking, liquefaction of both floodplain deposits along the Pajaro and Salinas Rivers in the Monterey Bay region and sandy artificial fills along the margins of San Francisco Bay, landslides in the epicentral region, and increased stream flow. Some significant findings and their impacts were:

  • Strong shaking that was amplified by a factor of about two by soft soils caused damage at up to 100 kilometers (60 miles) from the epicenter. Instrumental recordings of this ground shaking have been used to improve how building codes consider site amplification effects from soft soils.
  • Liquefaction at 134 locations caused $99.2 million of the total earthquake loss of $5.9 billion. Liquefaction of floodplain deposits and sandy artificial fills was similar in nature to that which occurred in the 1906 San Francisco earthquake and indicated that many areas remain susceptible to liquefaction damage in the San Francisco and Monterey Bay regions.
  • Landslides caused $30 million in earthquake losses, damaging at least 200 residences. Many landslides showed evidence of movement in previous earthquakes.
  • Recognition of the similarities between liquefaction and landslides in 1906 and 1989 and research in intervening years that established methodologies to map liquefaction and landslide hazards prompted the California legislature to pass in 1990 the Seismic Hazards Mapping Act that required the California Geological Survey to delineate areas potentially susceptible to these hazards and communities to regulate development in these zones.
  • The earthquake caused the flow of many streams in the epicentral region to increase. Effects were noted up to 88 km from the epicenter.
  • Post-earthquake studies of the Marina District of San Francisco provide one of the most comprehensive case histories of earthquake effects at a specific site. Soft soils beneath the Marina amplified ground shaking to damaging levels and caused liquefaction of sandy artificial fills. Liquefaction required 123 repairs of pipelines in the Municipal Water Supply System, more than three times the number of repairs elsewhere in the system. Approximately 13.6 km of gas-distribution lines were replaced, and more than 20% of the wastewater collection lines were repaired or replaced.

Professional Paper 1552 – Performance of the Built Environment

Cover image for Professional Paper 1552.

Professional Paper 1552  focuses on the response of buildings, lifelines, highway systems, and earth structures to the earthquake. Losses to these systems totaled approximated $5.9 billion. The earthquake displaced many residents from their homes and severely disrupted transportation systems. Some significant findings were:

  • Approximately 16,000 housing units were uninhabitable after the earthquake including 13,000 in the San Francisco Bay region. Another 30,000-35,000 units were moderately damaged in the earthquake. Renters and low-income residents were particularly hard hit.
  • Failure of highway systems was the single largest cause of loss of life during the earthquake. Forty-two of the 63 earthquake fatalities died when the Cypress Viaduct in Oakland collapsed. The cost to repair and replace highways damaged by the earthquake was $2 billion, about half of which was to replace the Cypress Viaduct.
  • Major bridge failures were the result of antiquated designs and inadequate anticipation of seismic loading.
  • Twenty one kilometers (13 mi) of gas-distribution lines had to be replaced in several communities and more than 1,200 leaks and breaks in water mains and service connections had to be excavated and repaired. At least 5 electrical substations were badly damaged, overwhelming the designed redundancy of the electrical system.
  • Instruments in 28 buildings recorded their response to earthquake shaking that provided opportunities to understand how different types of buildings responded, the importance of site amplification, and how buildings interact with their foundation when shaken (soil structure interaction).

Professional Paper 1553 – Societal Response

Dennis S. Mileti, editor

Professional Paper 1553

Professional Paper 1553  describes how people and organizations responded to the earthquake and how the earthquake impacted people and society. The investigations evaluate the tools available to the research community to measure the nature, extent, and causes of damage and losses. They describe human behavior during and immediately after the earthquake and how citizens participated in emergency response. They review the challenges confronted by police and fire departments and disruptions to transbay transportations systems. And they survey the challenges of post-earthquake recovery. Some significant findings were:

  • Loma Prieta provided the first test of ATC-20, the post-earthquake review process that places red, yellow, or green placards on shaken buildings. Its successful application has led to widespread use in other disasters including the September 11, 2001, New York City terrorist incident.
  • Most people responded calmly and without panic to the earthquake and acted to get themselves to a safe location.
  • Actions by people to help alleviate emergency conditions were proportional to the level of need at the community level.
  • Some solutions caused problems of their own. The police perimeter around the Cypress Viaduct isolated businesses from their customers leading to a loss of business and the evacuation of employees from those businesses hindered the movement of supplies to the disaster scene.
  • Emergency transbay ferry service was established 6 days after the earthquake, but required constant revision of service contracts and schedules.
  • The Loma Prieta earthquake produced minimal long-term disruption to the regional economy. The total economic disruption resulted in maximum losses to the Gross Regional Product of $725 million in 1 month and $2.9 billion in 2 months, but 80% of the loss was recovered during the first 6 months of 1990. Approximately 7,100 workers were laid off.


Oct 17, 1989 ce: loma prieta earthquake.

On October 17, 1989, the central coast of California experienced the Loma Prieta earthquake, the most damaging since the 1906 San Francisco earthquake.

Earth Science, Geology

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On October 17, 1989, the San Francisco Bay area of the United States was jolted by the Loma Prieta earthquake . The quake’s epicenter was near Loma Prieta Peak in the Santa Cruz Mountains. The magnitude 6.9 quake was the most powerful the state had experienced in several years.

The Loma Prieta earthquake was triggered by the mighty San Andreas Fault , where the massive Pacific plate slips northwestward. During the quake, the epicenter slipped up to two meters (six feet).

The Loma Prieta earthquake caused 63 deaths, 3,757 injuries, and about $6 billion in damage . Many casualties occurred as parts of several transportation routes , including the San Francisco-Oakland Bay Bridge and a busy freeway , collapsed .

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Understanding the 1989 Loma Prieta earthquake in an urban context

In an urban environment, the effect of a major earthquake such as the 17 Oct. 1989 Loma Prieta event can be pieced together by the infrastructure damaged or destroyed.

This study by Kevin M. Schmidt and colleagues details the effects of the Loma Prieta earthquake still detectable 25 years on and sheds light on the potential damage to infrastructure from future earthquakes along the San Andreas fault or the neighboring Foothills thrust belt.

Despite the absence of primary surface rupture from the 1989 Loma Prieta earthquake, patterns of damage to pavement and utility pipes can be used to assess ground deformation near the southwest margin of the densely populated Santa Clara or "Silicon" Valley, California, USA. Schmidt and colleagues utilized more than 1,400 damage sites as an urban strain gage to determine relationships between ground deformation and previously mapped faults.

Post-earthquake surveys of established monuments and the concrete channel lining of Los Gatos Creek reveal belts of deformation consistent with regional geologic structure. The authors conclude that reverse movement largely along preexisting faults, probably enhanced significantly by warping combined with enhanced ground shaking, produced the widespread ground deformation.

Such damage, with a preferential NE-SW sense of shortening, occurred in response to the 1906 and 1989 earthquakes and will likely repeat itself in future earthquakes in the region.

  • Earthquakes
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Story Source:

Materials provided by Geological Society of America . Note: Content may be edited for style and length.

Journal Reference :

  • K. M. Schmidt, S. D. Ellen, D. M. Peterson. Deformation from the 1989 Loma Prieta earthquake near the southwest margin of the Santa Clara Valley, California . Geosphere , 2014; DOI: 10.1130/GES01095.1

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National Academies Press: OpenBook

Practical Lessons from the Loma Prieta Earthquake (1994)

Chapter: 5. lifeline perspective, 5 lifeline perspective.

Ronald T. Eguchi and Hope A. Seligson

This paper provides a summary of important lessons learned after the Loma Prieta earthquake. As a result of this event, a comprehensive research agenda was sponsored by the National Science Foundation (NSF) in collaboration with the other National Earthquake Hazard Reduction Program (NEHRP) agencies. In total, over 80 research projects were funded addressing seismological, geo-technical, structural, lifeline, and socioeconomic topics. This particular paper summarizes research findings resulting from studies on lifeline performance. Lifelines considered in this paper include water supply, wastewater, natural gas, oil, electric power, and communication systems. Transportation systems and port and harbor facilities are addressed in companion papers.


After every major earthquake, there is a ''window of opportunity'' for researchers to advance the science of earthquake engineering. In cases where practical lessons are learned, these opportunities can result in significant changes in seismic analysis, design, and construction procedures. In order to substantiate these lessons, however, comprehensive, well-focused research is needed.

The NSF, along with the other NEHRP agencies, has been sponsoring earthquake-specific research since the 1971 San Fernando earthquake. In addition to the San Fernando earthquake, research initiatives were established after the 1985 Mexico City earthquake, the 1987 Whittier Narrows earthquake, and the 1989 Loma Prieta earthquake. Research agendas for these initiatives usually focused

on problems or issues uncovered as a result of these events. From this perspective, post-earthquake research has been problem focused.

The Loma Prieta earthquake offered a number of unique research opportunities. In the lifeline area, this earthquake allowed a detailed examination of seismic design procedures originally introduced as a result of the San Fernando event. In many cases, failure of lifeline systems was prevented because of these measures; in some cases, new vulnerabilities were uncovered. In general, research has been directed at explaining why certain design or construction measures work and why others do not.

Analyzing the earthquake vulnerability of our nation's lifeline systems is critical for several reasons. First, from the standpoint of replacement cost, life-lines account for approximately $4.5 trillion, or roughly 22 percent of the total built environment (Jones, 1993). Protecting these assets during natural disasters deserves special attention. Second, the recovery of cities after major natural disasters will depend in large part on the survivability of lifeline systems. As can be seen today in Florida, full recovery after Hurricane Andrew is slow, due in part to a lack of utility service. Many areas are still without electric power service. Finally, many systems are aged and ready for reconstruction or replacement. Taking advantage of the lessons learned from previous earthquakes offers an opportunity to enhance the seismic resistance of these systems. Identifying practical measures that can be applied to the seismic design, retrofit, and construction of lifeline systems is an essential first step in this overall process.

The purpose of this paper is to summarize practical lessons learned from research conducted as a result of the Loma Prieta earthquake. In particular, the emphasis is on research conducted to better understand the behavior of lifelines during earthquakes. While the lifeline area covers many different systems, several of the lessons learned apply to more than one lifeline. The applicability of these lessons to more than one lifeline will depend on whether they are connected or discrete systems. Connected systems generally include those that rely on transmission lines to convey service. Discrete lifelines may be classified as terminal or source facilities, for example, ports, harbors, and airports. In this paper, the emphasis is on connected systems, that is:

the water supply;


natural gas;

electric power; and


Even in the specialized area of lifeline earthquake engineering, it is difficult to identify all research efforts conducted as a result of an earthquake. For most government-sponsored research, the identification of ongoing efforts can usually

be made by contacting the funding organizations and requesting a list of awards. This procedure was used in the preparation of this paper. The primary organization providing research money to study this earthquake was the NSF. Information on organizations and individuals who were awarded research grants by the NSF was provided by Drs. S.C. Liu and C.J. Astill. This help was greatly appreciated.

In addition to the NSF, other organizations have provided some money to study this earthquake. The third section of this paper attempts to highlight these efforts, where known. Other efforts that may have been conducted with the support of private funds are not documented here, unless otherwise noted.

Because of the wide variety of lifeline systems, it is impossible for any one individual to list and summarize the research results. For this reason, the authors contacted many individuals to solicit their input in the preparation of this paper. The authors would like to first acknowledge the support of the discussant panel: Donald B. Ballantyne, Kennedy/Jenks Consultants; Professor Thomas D. O'Rourke, Cornell University; Charles Roberts, Port of Oakland; and Steven H. Phillips, Pacific Gas and Electric.

The authors would also like to acknowledge several individuals who contributed to parts of this paper or who offered technical advice in writing certain sections. These individuals are Douglas Honegger, EQE International; Sam Swan, EQE International; Professor Anshel Schiff, Stanford University; and Alex Tang, Northern Telecom. In addition, there were many individuals who kindly furnished reports or papers, in a very timely manner. These individuals are: Professor A. H-S Ang, University of California, Irvine; Dr. Jeremy Isenberg, Weidlinger Associates; Professor James O. Jirsa, University of Texas; Professor Barclay Jones, Cornell University; Professor Jamshid Mohammadi, Illinois Institute of Technology; and Stuart Werner, Dames & Moore. To all of these individuals, the authors express a sincere thanks.


The following section presents brief summaries of lifeline system performance in the Loma Prieta earthquake. These summaries are intended to give an overview of system response, rather than list specific component damages. Table 5-1 lists the utility agencies as surveyed by the Earthquake Engineering Research Institute's reconnaissance report. For each utility, an assessment of the earthquake's impact has been made, based on reported damage, response, and recovery. In addition, available data on water and sewage pipeline failures have been included. These data were taken from a compilation by the Technical Council on Lifeline Earthquake Engineering of the American Society of Civil Engineers (ASCE/TCLEE, 1992).

TABLE 5-1 Impact of Loma Prieta Earthquake on Bay Area Utilities

Water Supply

In general, aqueduct and reservoir facilities were undamaged. No major damage to dam facilities was reported, although several minor cracks on embankments and spillways were noted. Storage tanks were damaged in Los Gatos, San Jose, Los Altos Hills, Watsonville, Sunny Mesa, San Lorenzo Valley, Scotts Valley, and the Santa Cruz Mountains. Pipeline damage was extensive in areas of ground failure, such as San Francisco's Marina District, Santa Cruz, and Watsonville. Disruption lasted as long as two weeks in the harder-hit areas.

In San Francisco, isolated damages causing the loss of contents of a 750,000 gallon tank severely impacted the city's fire-fighting capability ( Figure 5-1 ). The flexibility of fire-suppression methods and the availability of the city's fire boat, however, minimized the impact of the tank failure.

Concern over possible contamination resulted in four cities in the epicentral area issuing "boil water" notices. The notices were in effect for one day in Los Gatos, three days in Watsonville, and seven days in Santa Cruz and San Lorenzo Valley (EERI, 1990).

Due to power outages and the lack of backup power at pumping plants, sewage was released into San Francisco and Monterey bays, as well as into the Pacific Ocean. These releases could have been avoided had adequate emergency power facilities been available (EERI, 1990).

san francisco earthquake 1989 case study

FIGURE 5-1 Twenty-two structural fires were reported immediately after the Loma Prieta  earthquake. The worst fire began inside a four-story apartment building in the  Marina District, probably as a result of a leaking gas main.

Sewerage facilities were damaged in areas that suffered damage to water systems. This damage is less evident, however, and the lack of water service and subsequent disuse of sewer facilities delayed documentation of damage. Damage had been reported in the city of Watsonville, Scotts Valley, and Santa Cruz. Minor damage was also reported at various regional wastewater treatment facilities (Kennedy/Jenks/Chilton, 1990).

Natural Gas

Pacific Gas and Electric's (PG&E) natural gas transmission system was virtually undamaged—only two leaks were reported. Both were repaired without customer interruption. However, distribution systems in several areas were severely impacted. Over 1,000 pipeline leaks were reported system-wide, and three low-pressure systems were so heavily damaged that replacement was required. Replacement consisted primarily of insertion of plastic pipe into existing mains and services ( Figure 5-2 ). The distribution system in the Marina District of San Francisco was replaced within one month, at a cost of $17 million. Fifty-one hundred customers were affected. Reconstruction of the Watsonville low-pressure system was complete within three weeks, affecting 166 customers. One hundred and forty customers were impacted in Los Gatos, where main restora-

san francisco earthquake 1989 case study

FIGURE 5-2 Within the Marina District, damage to cast-iron natural gas pipe was so extensive that rather than repairing damaged pipe, new polyethylene pipe was inserted in existing mains and services.

tion was accomplished within ten days, and service restoration was complete within a month (Phillips and Virostek, 1990). Total gas system damages have been estimated at $19 million (Matsuda, 1993).

One of the most labor-intensive parts of the restoration process was the relighting of services. $7 million was incurred after the earthquake to relight pilots that had been turned off as a result of the earthquake (Matsuda, 1993). Service relights, which were accomplished within ten days, were required by 156,355 customers. The majority of relights resulted from customers unnecessarily turning off their own gas in response to hastily worded media messages, which recommended shutoff without specifying "if you smell or hear gas." At the peak of the relight effort, 1,183 servicemen were utilized. Outside utility companies contributing manpower to the relight effort included Southern California Gas, San Diego Gas and Electric, Mountain Fuel, Sierra Pacific, Northwest Natural Gas, and Washington Natural Gas (Phillips and Virostek, 1990).

Oil Refineries And Associated Facilities

Most of the region's refineries and tank farms are located along the San Francisco Bay in Alameda and Contra Costa counties. Numerous tanks at soft-

soil sites were damaged, predominantly tanks that were full or nearly full. Typical damage modes included elephant's foot buckling, sometimes associated with loss of contents; damage to associated piping; and uplift of unanchored tank walls. It was reported that all leaks were contained within containment dikes and that no fires resulted (EERI, 1990).

Electric Power

Primarily as a result of direct damage to transmission substations, 1.4 million PG&E customers lost power following the Loma Prieta earthquake. Power was restored to most of San Francisco within seven hours, and all but 12,000 customers had power within two days (PG&E, 1990). In many cases, power restoration was accomplished by bypassing damaged equipment and operating with reduced levels of circuit protection. Damage to power generation and bulk transmission facilities was estimated to be $19 million, while distribution added an additional $4 million in damages (Matsuda, 1993).

Damage was severe in several 500-kV switchyards, including Moss Landing in Monterey Bay and Metcalf in the San Jose area. Seven 500-kV circuit breakers required replacement, at a cost of $700,000 each. These items are not stockpiled by PG&E, and only two came from within the PG&E system. The rest had to be obtained from various sources, including the Tennessee Valley Authority, the Los Angeles Department of Water and Power, and Southern California Edison (PG&E, 1990). Power plant damage was minor, but several plants were forced off-line by substation damage. The rapid loss of power throughout parts of the system was fortuitous in that many distribution systems were no longer energized when damaging situations, such as wrapping of lines, occurred.


The most notable impact of the earthquake on telecommunications was the monumental increase in call volume, both locally and worldwide. AT&T reported 27.8 million calls attempted to the 415 and 408 area codes the day after the earthquake. Nine and a half million of these calls were completed, more than double the normal daily volume of 3.5 million. Pacific Bell also reported heavy volume within the Bay Area—80 million calls versus the norm of 55 million. Heavy volumes led to dial tone delays, which in some cases impacted emergency communications (911) activities, and there were several days of service degradation during peak load times (EERI, 1990).

Direct damage to telecommunications facilities and equipment was limited. Most difficulties resulted from failure of backup power systems or insufficient backup power capacity.


Post-earthquake research activities usually fall into one of two categories: federally sponsored research or research funded by private or semi-public organizations. In this paper, the emphasis is on research sponsored by the federal government, that is, the NSF. Other efforts, where publicly acknowledged, are also identified later in the paper.

Nsf-Sponsored Research

While the risk to lifeline systems in earthquakes is generally acknowledged, it is not necessarily understood. Some research into the causes of damage and disruption of lifeline systems in earthquakes has been completed, but the amount is small relative to many other areas of earthquake hazard mitigation study. Data from the NSF Research Awards Database for earthquake hazard mitigation studies were reviewed for the years 1980-1990 (Seligson et al., 1991). Of the approximately $160 million spent, only about $18 million (11 percent) was spent on lifeline research. As noted in the original review, this figure does not incorporate monies routed by funded organizations (e.g., the National Center for Earthquake Engineering Research) into lifeline research and will, therefore, underestimate actual dollars spent on lifeline studies. However, a consistent comparison between general funding patterns and funding in the post-earthquake environment may be made by looking exclusively at NSF funding.

While recent funding levels for lifeline earthquake studies are an average of 11 percent of the total amount spent, this number may increase in the post-earthquake environment. Of the approximately $1.4 million in NSF funds awarded to study the 1987 Whittier Narrows earthquake, 24.5 percent were related to the study of lifelines (based on a title search of the NSF awards database, 1980-1990). Studies of structural performance received the greatest percentage of funds, approximately 37.7 percent of the total.

Following the Loma Prieta earthquake, the NSF funded $4.2 million in research through the Loma Prieta Initiative. These funds sponsored various engineering investigations, including studies addressing geotechnical, structural, seismological, and socioeconomic topics. The percentage breakdown by discipline is shown in Figure 5-3 . Of this $4.2 million, about 15 percent was spent investigating lifeline issues, while 30.3 percent was spent on structural research.

Of the monies spent on lifeline research between 1980 and 1990, the majority has gone to investigating water and transportation system facilities. In general, water lifelines have received about 30 percent of the funding dedicated to lifeline topics. This number may be even larger, as studies of various multipurpose, multi-lifeline components are not included in this estimate. If the monies spent on pipeline and tank research were included, this number might be as high as 60 percent. In addition, 24 percent has gone to transportation studies. The

san francisco earthquake 1989 case study

Figure 5-3 Breakdown of NSF Research in the Loma Prieta Initiative ($4.2 Million Total)

remainder is distributed among communications (3.3 percent), electric power (2.4 percent), natural gas (1.6 percent), wastewater (0.6 percent), disaster preparedness and emergency response (3.4 percent), and other topics.

In the immediate post-earthquake environment, funding is often focused on lifeline facilities that sustained the most damage. Following the Whittier Narrows event, 35 percent of the lifeline funding went to dams, and 27.4 percent went to bridges and overpasses. The Loma Prieta Initiative allocated 39.4 percent of lifeline monies to water studies, 30.7 percent to transportation topics, 15.6 percent to power and 14.3 percent to gas. Notably absent in the Loma Prieta studies were studies of port or harbor facilities and telecommunications.

It is interesting to note the inclusion of a significant number of socioeconomic topics in the research funded by the NSF (14.6 percent). Recently, the possibility of regional events with far-reaching impacts has prompted the study of earthquake impacts on the community in terms of direct damage, utility losses, and higher order, regional economic losses. Such research has required a multidisciplinary approach and is reflected in the variety of socioeconomic topics included in the Loma Prieta Initiative. These topics include not only community response and macroeconomic effects but secondary effects, such as those on the housing and rental markets and on the earthquake insurance industry.

Other Research Efforts

While publicly funded post-earthquake research has done a great deal to improve the state of the art in earthquake engineering, additional proprietary

research whose results are not readily available has also been conducted. Some of these results, however, are gradually reaching the public domain through various vehicles including:

the Electric Power Research Institute, which has sponsored extensive research on the damage and vulnerability of facilities relevant to the electric power and nuclear industries; several workshops that serve to exchange information have been held, including a ''Wide Area Disaster Preparedness Conference'' (1991), which addressed such issues as performance, restoration, mitigation, and preparedness;

the National Communications System, which co-sponsored a workshop in 1991 with the NSF entitled "Modeling the Impact of Major Earthquakes on Communications Lifelines: Research Accomplishments and Needs," and a second workshop in 1992 entitled "Assessment of State-Of-The-Art Approaches to Communication Lifeline Modeling for Earthquake Disasters; the purpose of these workshops was to "review the state of the art in modeling the effects of major earthquakes on communications lifelines and to assess the technical feasibility of developing models if none existed"; the presenters at this workshop discussed research results on various themes including seismic testing, actual performance, predictive damage and outage models, and mitigation and preparedness measures (NCS/NSF, 1991, in press); and

conference proceedings from various professional organizations, such as the American Society of Civil Engineers/Technical Council for Lifeline Earthquake Engineering (ASCE/TCLEE) and the Earthquake Engineering Research Institute (EERI).

Lessons Learned

In this section, lessons learned as a result of research conducted after the Loma Prieta earthquake are discussed. Although many lessons have been documented, only those that have had a major impact on the analysis or design of lifeline systems are summarized. In general, lessons learned after major earthquakes fall into one of three categories:

lessons that identify previously unknown seismic vulnerabilities;

lessons that substantiate or contradict prior understandings of seismic vulnerability and/or design; and

lessons that identify new variables with regard to vulnerability assessment and/or seismic design.

In all three cases, some level of research is necessary to quantify the significance of the lesson learned or finding uncovered.

The funding of post-earthquake research has been based, in part, on the amount of damage observed in the earthquake and the impact that the earthquake

had on the livelihood or welfare of the region. The results of reconnaissance surveys play a significant role in establishing research priorities. As seen in the 1971 San Fernando and the 1987 Whittier Narrows earthquakes, many structures and facilities were affected by these moderately sized earthquakes. As a result, significant research efforts were initiated to refine seismic vulnerability analysis methods and improve seismic design measures. The 1992 Landers earthquake, although larger in magnitude (M7.1), caused very little damage to buildings and lifelines. The primary reason for this lack of damage was that the earthquake occurred in a sparsely populated area of southern California. Because very little damage was observed, no major research efforts were initiated after this event, other than seismological efforts.

The Loma Prieta earthquake, however, uncovered some previously unknown vulnerabilities, primarily in the area of transportation structures. In addition, sufficient data were generated to refine the understanding of the performance of a number of other structures. A wealth of data was produced for quantifying the performance of underground lifeline components, particularly in liquefaction zones. With the exception of the 1971 San Fernando earthquake, the 1989 Loma Prieta event is responsible for the largest data set on earthquake damage to underground pipelines. As will be discussed, research conducted after the Loma Prieta earthquake was invaluable in establishing the appropriate earthquake hazard mitigation strategy for pipelines located in the city of San Francisco.

The emphasis here is on practical lessons that result in a better understanding of the seismic performance of these systems. As discussed in the introduction, the lifelines covered in this paper include:

Water Supply And Wastewater Systems

Many of the studies funded by the NSF after the Loma Prieta earthquake focused on the performance of water and wastewater facilities. In an earlier section of this paper, an analysis of earthquake damage data collected by ASCE/TCLEE on underground water pipelines showed that a significant number of systems located within 70 miles of the epicenter suffered some level of earthquake damage ( Table 5-1 ). Although it is difficult to estimate the total amount of dollars spent to repair these systems, it is believed that this amount is in the tens of millions.

Historically, the amount of research on water and wastewater systems, mea-

sured in dollars, is among the largest for lifelines research. This is probably due to several factors. First, these systems have been shown to be extremely vulnerable during earthquakes. Earthquake damage to these systems has been observed in virtually every modern U.S. event. Second, because most of these systems are publicly owned, there is less reluctance on the part of the utility owner or operator to reveal earthquake damage data that may be useful for research purposes. In fact, for many of the affected water utilities, subsidization of repair costs by the Federal Emergency Management Agency is based on detailed summaries of repair activities. Therefore, there are usually good data associated with the earthquake performance of these systems.

Some of the major lessons learned from research conducted on water and wastewater facilities are listed below:

The performance of underground pipelines is closely correlated with the amount of differential movement observed in liquefaction zones .

Research conducted primarily by Professor T.D. O'Rourke at Cornell University has shown that in the Marina District, where significant liquefaction ground failure occurred ( Figure 5-4 ), the number of pipeline repairs per unit

san francisco earthquake 1989 case study

FIGURE 5.4 Extensive ground failure was  observed in the Marina District  of San Francisco. In addition to  major damage to sidewalks and  roadways, extensive damage  to many of the underground  utilities was observed.

length appeared to be closely correlated with the amount of differential displacement or settlement observed in that area. It was noted that very little damage to underground pipes was observed in areas immediately outside of the Marina District. The significance of this finding is that an assessment of the seismic vulnerability of underground pipes in future earthquakes will depend, in part, on locating these potential ground failure areas and estimating the extent of permanent ground displacement.

At low strain levels, negligible slip occurs between the soil and the pipeline; as a result, ground strains and pipeline strains can be assumed to be equal .

For the past several years, Weidlinger Associates, along with other organizations, has set up an elaborate pipeline response monitoring experiment in anticipation of the Parkfield earthquake. This experiment is designed to capture needed information on the response and behavior of different kinds of underground pipelines subject to permanent ground displacement caused by surface fault rupture. Although the Loma Prieta earthquake did not produce fault rupture at the Parkfield site, it did generate low-level ground motions that caused strains in the pipe. This suggests that the assumptions used in the design of critical pipeline systems (e.g., pipe strains from ground distortion are roughly equal to or slightly less than ground strains) are reasonable, at least for small strain levels.

Computer simulations of the post-earthquake performance of the San Francisco Auxiliary Water Supply System (AWSS) correlated well with actual leakage data. Rapid loss of water supply was predicted based on the locations of actual leaks .

Extensive research on the expected performance of the AWSS system had been performed by C.R. Scawthorn (EQE International) and T.D. O'Rourke (Cornell University) prior to the Loma Prieta earthquake. The purpose of this research was to (1) calibrate system models developed from data provided by the San Francisco Fire Department and (2) to simulate expected flow rates given probable leak locations caused by a hypothetical earthquake. In the 1989 Loma Prieta earthquake, one of the serious failures to the AWSS system occurred in a pipeline located in the South of Market area ( Figure 5-5 ). As a result of this failure, water supply from the 750,000 gallon Jones Street tank was lost in 30 to 45 minutes. Computer simulations run after the earthquake verified the extreme vulnerability of water supply to leaks in this area and confirmed that total water supply in the one tank could be lost within a fraction of one hour. Important recommendations that resulted from this study include the suggestion to install automatic valves that would sense a rapid loss of water in the system and shut off the surviving water supply.

san francisco earthquake 1989 case study

FIGURE 5-5 These specially designed cast-iron pipes were part of the AWSS in the South of Market area of San Francisco. Although there were few failures in this system, those that did occur had major impact on the fire-suppression water supply system.

Nonstructural components within water and wastewater treatment facilities are prone to damage from sloshing effects .

After the Loma Prieta earthquake, D. Ballantyne of Kennedy/Jenks Consultants performed a comprehensive survey of the earthquake performance of all water and wastewater treatment facilities in the San Francisco Bay area. The survey indicated that, for the most part, the structural systems at these facilities survived with little or no damage. In contrast, many nonstructural components that are critical to the effective operation of these facilities were severely impacted. It was found that sloshing effects, which are typically considered in the analysis and design of water storage tanks, can cause significant damage to other treatment plant facilities. It was concluded that much of the observed damage could be eliminated if the same principles used in the design of storage tanks were also employed for these other components.

Natural Gas Systems

Research on natural gas system performance was sponsored primarily by the following organizations: PG&E, Southern California Gas Company (SCG), and

the NSF. A summary report of PG&E's response to the earthquake was prepared by PG&E (Phillips and Virostek, 1990). A detailed examination of gas system repairs in the city of San Francisco was funded by SCG and reported in a paper by Douglas G. Honegger (Honegger, 1991). An NSF-sponsored investigation of the causes of fires following the Loma Prieta earthquake was performed at the Illinois Institute of Technology (Mohammadi et al., 1992). Another NSF study, aimed at correlating gas system performance with other earthquake effects, is currently being prepared by the authors of this paper.

Key lessons learned from these studies are

Natural gas transmission pipelines and distribution mains demonstrated a high degree of ruggedness when large permanent ground deformations were absent, similar to performance in past earthquakes .

Experience during the Loma Prieta earthquake confirmed the ruggedness of buried, welded steel pipeline systems located in competent soils. The PG&E high-pressure transmission system suffered only two cracked welds in a 12-inch-diameter, 1930s vintage pipeline, which were repaired without interruption of service. Of the 25 distribution main repairs made in San Francisco, 23 were to older cast-iron pipe, and 20 were in areas known to have experienced permanent ground deformation (Phillips and Virostek, 1990; Honegger, 1991).

Damage to gas distribution lines in the city of San Francisco was largely limited to areas that experienced permanent ground deformation resulting from liquefaction, slope failure, and settlement of alluvial fill .

Examination of patterns of repair to the gas system in the city of San Francisco highlighted the high degree of vulnerability of these systems to permanent ground deformation. Examination of repair patterns outside of the Marina District showed concentrations of damage in the general vicinity of both Market Street and Golden Gate Park (Honegger, 1991). This behavior is consistent with observations from the 1987 Whittier Narrows and 1971 San Fernando earthquakes.

A strong correlation was observed between damage to structures and repairs to gas services .

Concentrations of repairs to gas services coincided with areas of San Francisco that experienced significant structural damage. The Modified Mercalli intensity contours as drawn for this event, however, did not correlate well with repair locations. Incomplete information suggests that the correlation of gas service repairs with contours of Modified Mercalli Intensity is weak, if not nonexistent, and is an area of research deserving further attention (Honegger, 1991).

There is still much to be done to educate the public, especially residential customers, about risks related to gas leakage following earthquakes .

Despite efforts by the gas companies in California to educate the public, most of the 156,000 PG&E customer calls in the ten days following the earthquake were to relight services that were unnecessarily shut off. The ability of PG&E to facilitate the relight effort was attributable to existing arrangements with other gas utilities in California, Utah, Oregon, and Washington to provide emergency service personnel. In the study by Mohammadi et al. (1992), over 90 percent of the fires in the city of San Francisco were related to electrical wiring or equipment, stoves, candles, and unknown sources. The relatively low number of fires directly related to natural gas leakage is consistent with past surveys of fire initiation following earthquakes (e.g., URS, 1988).

Electric Power Systems

While power system performance provides some of the most visible examples of earthquake impacts on lifelines, NSF-sponsored research funding has been rather limited. Part of the reason for this is that other organizations, such as the Electric Power Research Institute, have taken the lead in sponsoring research in this area. Valuable lessons that have resulted from these efforts are as follows:

A methodology developed to estimate the reliability of electric power transmission systems has identified the need to consider causes of power outage, other than direct damage, in system design, retrofit, and emergency planning .

In response to significant power outages in areas of extensive as well as limited damage, research conducted at the University of California, Irvine (Ang et al., 1992) has been directed toward developing a methodology to estimate the likelihood of electric power transmission system failure that incorporates failures due to both direct damage and power imbalances. The methodology was tested using the PG&E system in the south San Francisco area, and the results reportedly compared favorably with actual power loss patterns. Although additional validation exercises are needed, the research serves to draw further attention to possible causes of power outage, other than direct damage to facilities.

Regardless of the level of damage, power outages in urban areas can be expected to last several days after a significant earthquake to allow for inspection of high-rise buildings for gas leaks and ignition sources .

The extended power outage in downtown San Francisco following the Loma Prieta earthquake resulted not from direct damage but from the need to perform building-by-building gas leak surveys prior to energizing the local power grid. While most of the city had power restored within a day of the earthquake, the high-rise district was without power for roughly 48 hours (EQE, 1990).

Consistently poor performance of high voltage (500-kV live tank) circuit breakers in major earthquakes has shown that while seismic strengthening

schemes may be adequate for small and moderate ground motions, the), may not prevent failure during significant ground motion .

Power system failures are closely linked to failure of components at high voltage substations, including live-tank circuit breakers. The vulnerability of these components is generally acknowledged, and various retrofit strategies have been tried. All seven of the 500-kV live-tank circuit breakers in the strongly shaken areas of the Loma Prieta earthquake (the Metcalf and Moss Landing substations) failed. The ceramic columns supporting the interrupter heads on these circuit breakers had been retrofitted with internal fiberglass rods to help hold the columns together under seismic loads. Although a significant number of these columns failed under the loads imposed by this earthquake, it was noted that, on a few columns at Metcalf (where the intensity of ground shaking was slightly less than that at Moss Landing) only the porcelain was shaken loose, leaving the interrupter head to be supported by the reinforcing bar. The continued integrity of the reinforcing rods implies that some level of protection is offered by this retrofit scheme (EQE, 1990).

The seismic ruggedness of 500-kV dead-tank circuit breakers was demonstrated .

Although all seven 500-kV live-tank circuit breakers at Moss Landing and Metcalf were destroyed, the 500-kV dead-tank circuit breakers at these sites were undamaged. Many California power utilities are replacing older live tank circuit breakers at critical locations with shake-table-tested dead-tank circuit breakers. The Loma Prieta earthquake confirmed that these replacement breakers can remain functional after being subjected to strong ground shaking.

Communication Systems

As stated in earlier sections of this paper, it is difficult to determine the amount of research money spent to develop seismic measures for telecommunication systems. Part of the reason for this is that the majority of this research is conducted in-house by privately owned utilities, and the results of this research are only made available through limited conferences or workshops. Nevertheless, a number of valuable lessons have been documented in recent workshops and meetings.

In the United States, the most recent attempts at summarizing relevant research on telecommunication performance during earthquakes have been the two National Communications Systems/NSF workshops. The first workshop was held in 1991 in Memphis, Tennessee; the second workshop was held last year in Seattle, Washington. In both workshops, the focus was on developing improved models for predicting telecommunication performance during earthquakes. One of the case studies used in these evaluations was the Loma Prieta earthquake.

Another source of telecommunication research has been the U.S-Japan cooperative research program. In 1992, a set of meetings were held between U.S. researchers and engineers from NTT in Japan (Tang, 1992). During these meetings, visits were made to several NTT facilities, and discussions were held on different technical topics. The goal of these meetings was to explore the possibility of a formal joint agreement between the United States and Japan in the area of lifeline earthquake engineering with an emphasis on telecommunication systems. The results of these visits are summarized in a technical report prepared by the NSF (Tang, 1992).

Based on a review of the above material, the following major lessons are documented:

Sufficient slack in fiber-optic cable can help to mitigate service disruption or failure due to large relative displacements .

One of the important lessons learned by the Japanese regarding the seismic resistance of fiber-optic cable was that sufficient slack in the cable could be used to mitigate seismic damage. Figure 5-6 shows a fiber-optic cable that was stretched when one of the upper spans of the Bay Bridge collapsed during the Loma Prieta earthquake. Although the cable was stretched, there was sufficient slack to accommodate the displacement. Only 3 of 108 fibers were damaged.

san francisco earthquake 1989 case study

FIGURE 5-6 This photo shows a view of the collapsed upper deck of the Bay Bridge. Note in the background the fiber-optic cable that fell with the upper deck.

san francisco earthquake 1989 case study

FIGURE 5-7 Earthquake countermeasures for fiber-optic cables (Yagi et al. 1992).

The Japanese are using this concept in the design of their underground manholes. One of the major concerns in the design of these facilities is that local liquefaction may uplift or displace these units. If this happens, there is concern that the cables contained within these units would either break or stretch. Therefore, in order to prevent possible failure, the Japanese have designed a number of different installations that incorporate cable slack as a design parameter. Several of these installations are displayed in Figure 5-7 .

Damage to telecommunication facilities will generally affect only local communication; the national telecommunication network is robust enough that outages in one part of the country should not affect other regions .

Several studies performed for the National Communications System verified that on a nationwide scale, earthquakes should have little or no effect on calls within other regions. Several scenarios were run to determine the number of facilities that would be affected in a large earthquake on the Hayward fault in northern California. Based on fairly conservative damage criteria, it was determined that in such an event, the capacity of the network would drop to a possible low of about 67 percent in California and between 92 and 98 percent across the entire United States. These figures do not include, however, reductions in capacity caused by overload on the system.


One measure of the benefit of a particular research effort is the transferability of its methods, conclusions, or results to other areas of the country or to other types of facilities or systems. The transferability of earthquake research is critical, since many seismically active areas of the United States have not experi-

enced the effects of a large earthquake. Notable areas without modern, large earthquakes include the New Madrid Seismic Zone; the Wasatch Fault Zone; the Charleston, South Carolina area; the northeastern United States; and the Pacific Northwest.

Many of the procedures available for the seismic analysis or design of lifeline systems and components are based on methods originally developed for California lifelines. In general, there are many similarities between California utility systems and systems in other parts of the United States. For example, the design and construction of major natural gas transmission pipelines, particularly interstate lines, are very similar, partly because their operation is federally regulated, and because they are designed and constructed under the same design guidelines. This is also the case for major oil pipelines. Because of these similarities, it is logical to assume that earthquakes exhibiting the same effects (such as liquefaction) would cause similar types of damage. Possible exceptions include the traveling wave effects that may be present in large midwestern earthquakes. These earthquakes may cause significantly more damage to underground pipelines or to structures sensitive to long-period effects (e.g., long-span bridges) than west coast earthquakes.

Some of the lessons learned from the Loma Prieta earthquake that are considered transferable are:

Pipeline damage models for ground failure effects (e.g., liquefaction) should be applicable in other parts of the United States .

The ground failure effects observed in northern California after the Loma Prieta earthquake can and have occurred in other parts of the United States. Extensive liquefaction ground failures were observed during the 1811 and 1812 New Madrid earthquakes. It is likely that these types of ground failures will be responsible for the majority of the damage incurred by well-designed pipelines. Therefore, pipeline damage models developed primarily from California data should be applicable to earthquakes in other parts of the United States. Perhaps the one area where there is a lack of data in pipeline response data is in characterizing the effects of wave propagation. Data from other parts of the world (e.g., the 1985 Mexico City earthquake) will be needed to quantify the effects from this phenomenon.

Potential damage to nonstructural elements in water treatment facilities could be more severe in earthquakes outside of California .

Many of the treatment facilities (storage tanks, sedimentation basins) that suffered significant damage during the Loma Prieta earthquake are considered to be long-period sensitive structures. Sloshing effects were the primary cause of damage to these facilities. In a large New Madrid event, it is expected that larger areas will be impacted by ground motions containing low-frequency energy. As a result, facilities that are sensitive to these types of frequencies would be ex-

pected to experience similar or more extensive damage. Damage may also be more significant because of the longer durations expected for midwestern earthquakes.

It is expected that after any significant U.S. earthquake, power outages in urban areas will last longer than in less developed areas, due to the need to inspect high-rise structures for gas leaks and ignition sources .

The extended power outage in downtown San Francisco following the Loma Prieta earthquake resulted not from direct damage but from the need to perform building-by-building gas leak surveys prior to energizing the local power grid. While most of the city had power restored within a day of the earthquake, the high-rise district was without power twice as long—roughly 48 hours. Similar occurrences are anticipated for other U.S. earthquakes, and the impact could be far greater, particularly for a New Madrid type of event, which has the potential to simultaneously affect numerous highly developed urban areas.

The use of cable slack in fiber-optic cable installations can reduce or eliminate potential interruption of service in any area expected to undergo significant movement or displacement .

As a practical mitigation measure, this procedure should apply to any seismic region of the world. As indicated in previous discussions, this technique has been developed by NTT engineers to mitigate the effects of liquefaction on underground manhole structures. This technique may be particularly useful in the Midwest, where extensive liquefaction is expected in large earthquakes.


As a result of lessons learned from the Loma Prieta earthquake, several encouraging trends have developed. One of the more significant efforts is the collection and documentation of pipeline failure data. Only by collecting this information will researchers be able to validate analytical models for pipeline performance or to develop empirical models that apply over a wide range of seismic hazard effects and severity levels. Therefore, continued efforts to collect and document this-data are encouraged.

Another area deserving further study is the area of ground failure assessment. It has been shown that pipeline performance is tied very closely with the types and levels of permanent ground displacement observed during an earthquake. If such a strong correlation exists, then the assessment of pipeline performance becomes a seismic hazard microzonation problem (i.e., identifying potential areas of ground failure and amounts of displacement). This further supports the continuation of efforts to map these types of hazards on a broad regional scale.

In earlier discussions of lessons learned, it was stated that system vulnerability methods were useful in identifying areas of potential outage. Ang et al. (1992) discussed the benefit of using these methods to quantify electric power system vulnerability; O'Rourke et al. (1990) used these methods to validate the vulnerability of the AWSS in the city of San Francisco and the rapid loss of water after the Loma Prieta earthquake. Although these methods have been used in areas outside of California, their application has not been widespread. One possible direction of future research is to ensure the development of appropriate regional models for system vulnerability assessment. Models that may vary from region to region include seismic hazard models (strong ground shaking, liquefaction, surface fault rupture, landslide, tsunami, and seiche) and seismic vulnerability or fragility models.

The following recommendations for collaborative research are made:

Stronger collaboration is needed between those researchers that characterize the severity of ground motions and ground failure effects (e.g., liquefaction) and those that model the seismic vulnerability of systems. Because lifeline systems cover large geographical areas, an assessment of seismic hazards on a broad regional scale is necessary. It is important that the appropriate seismic hazard measures are quantified and that this information is provided to the system modelers in the most useful format possible.

Researchers who model the performance of lifeline systems must also coordinate their studies with social scientists. It is becoming clear that to describe the full impact of these catastrophic events, it is necessary to investigate secondary and higher order effects of the event. Previous studies (ATC, 1991) have stated that the more significant losses associated with the failure of lifeline systems will come from lifeline disruption and not from repair costs. Furthermore, social disruption costs, although difficult to quantify, may also be significant. Therefore, collaboration between engineers and social scientists must be strengthened.

Stronger partnerships between the research community and industry must be developed. Many research efforts have benefited from such partnerships, and the results of these collaborations are more likely to lead to implementation of a study's recommendations. Currently, a federal initiative (spearheaded by the Federal Emergency Management Agency and the National Institute of Standards and Technology) to develop a plan for developing and adopting seismic design standards for public and private lifelines is underway. In order to ensure that such an effort is successful, it is essential that stronger partnerships between the research community, government agencies, and industry be developed. One of the most effective ways to initiate this partnership is to involve the end users (i.e., the lifeline operators) in government-sponsored research programs.

Ang, A., H-S.J. Pires, R. Schinzinger, R. Villaverde, and I. Yoshida. 1992. Seismic Reliability of Electric Power Transmission Systems — Applications to the 1989 Loma Prieta Earthquake . University of California at Irvine, prepared for the National Science Foundation and the National Center for Earthquake Engineering Research.

ATC, 1991. Seismic Vulnerability and Impact of Disruption of Lifelines in the Conterminous United States . Applied Technology Council Report No. ATC-25, Redwood City, California.

ASCE/TCLEE. 1992. ''TCLEE Pipeline Failure Database.'' Prepared for the National Science Foundation.

Boheim, K.B., and C.M. Kelly. 1992. "Post-Earthquake Performance of Telecommunications Networks." Proceedings of the Fifth U.S.-Japan Workshop on Earthquake Disaster Prevention for Lifeline Systems , Tsukuba, Japan.

EERI. 1990. Earthquake Spectra: Loma Prieta Earthquake Reconnaissance Report , Earthquake Engineering Research Institute, Supplement to Volume 6, May.

Electric Power Research Institute. 1991. Proceedings: Wide-Area Disaster Preparedness Conference . EL-7298, EPRI, Palo Alto, California.

EQE. 1990. The October 17, 1989 Loma Prieta Earthquake: Effects on Selected Power and Industrial Facilities . Prepared for the Electric Power Research Institute.

Honegger, D.G. 1991. "Gas System Repair Patterns in San Francisco Resulting From the 1989 Loma Prieta Earthquake." In Proceedings of the Third U.S. Conference on Lifeline Earthquake Engineering , Monograph No. 4. Technical Council on Lifeline Earthquake Engineering, American Society of Civil Engineers.

Isenberg, J., E. Richardson, H. Kameda, and M. Sugito. 1991. "Pipeline Response to Loma Prieta Earthquake." J. of Structural Engrg., 117(7), ASCE, New York, N.Y.

Jones, B. 1993. "New Directions in Research, Societal and Economic Studies." Presented at the 1993 Annual Meeting of the Earthquake Engineering Research Institute, Seattle. Washington.

Kennedy/Jenks/Chilton. 1990. 1989 Loma Prieta Earthquake Damage Evaluation of Water and Wastewater Treatment Facility Nonstructural Tank Elements . Prepared for the National Science Foundation, K/J/C 896086.00.

Matsuda, E. 1993. Personal communication.

Mohammadi, J., S. Alyasin, and D.N. Bak. 1992. "Investigation of Cause and Effects of Fires Following the Loma Prieta Earthquake." Illinois Institute of Technology, Report IIT-CE-92-01, NSF Grant BCS-9003557.

NCS/NSF. 1991. Earthquake Workshop Proceedings: Modeling the Impact of Major Earthquakes on Communication Lifelines . Co-Sponsored by the National Communications System and the National Science Foundation.

NCS/NSF. In press. Earthquake Workshop Proceedings: Assessment of State-of-the-Art Approaches to Communication Lifeline Modeling for Earthquake Disasters . Co-Sponsored by the National Communications System and the National Science Foundation.

O'Rourke, T.D., H.E. Stewart, F.T. Blackburn, and T.S. Dickerman. 1990. Geotechnical and Lifeline Aspects of the October 17, 1989 Loma Prieta Earthquake in San Francisco . Technical Report NCEER-90-0001, NCEER, Buffalo, N.Y.

O'Rourke, T.D., J.W. Pease, and H.E. Stewart. 1992. "Lifeline Performance and Ground Deformation During the Earthquake." The Loma Prieta, California Earthquake of October 17, 1989-Marina District . U.S. Geological Survey Professional Paper 1551-F, Washington D.C.

PG&E. 1990. PG&E and the Earthquake of '89 , Pacific Gas and Electric Company. San Francisco, California.

Phillips, S.H., and J.K. Virostek. 1990. Natural Gas Disaster Planning and Recovery: The Loma Prieta Earthquake . Pacific Gas and Electric Company, San Francisco, California.

Seligson, H.A., R.T. Eguchi, L. Lund, and C.E. Taylor. 1991. Survey of 15 Utility Agencies Serving the Areas Affected by the 1971 San Fernando and the 1987 Whittier Narrows Earthquakes . Prepared for the Natural Science Foundation.

Tang, A. 1992. "Technology Exchange with NTT on Seismic Protection of Telecommunication Facilities." Prepared for the National Science Foundation, ASCE/TCLEE.

URS. 1988. "Risks of Earthquake-Induced Gas Fires in Residential Housing." Report prepared for Southern California Gas Company.

Yagi, K., S. Mataki, and T. Sakurada. 1992. "Aseismic Countermeasure for Optical Fiber Cable in Liquefiable Ground." Proceedings of the Fifth U.S.-Japan Workshop on Earthquake Disaster Prevention for Lifeline Systems , Tsukuba Japan.


Thomas d. o'rourke, cornell university.

It is a pleasure to be here. I have four points I would like to make, some of which will echo those made by others. Finally, I would like to give a warning about our lifeline and infrastructure systems.

Liquefaction-induced ground deformation was of key importance to the performance of the water supply in San Francisco and portions of the East Bay during the Loma Prieta earthquake. Correlations among areas of soil liquefaction and locations of buried pipeline damage show a clear pattern of system performance that depends on the severity of liquefaction and the spatial distribution of ground movement. These observations provide a practical framework for assessing the most vulnerable portions of the piping system and anticipating the effects of future earthquakes.

These spatial observations can be used to come up with some simple rules useful for planning, emergency response, and development. Since buried systems depend so much on the deformation of the ground, the fate of the ground should be looked at as being, in part, the fate of these systems. Subsurface data have been used to characterize geometry and in situ properties of loose fills in areas of San Francisco, which were subject to liquefaction and ground failure. It has been found that mapping thickness of the submerged fills, a very simple parameter, is a good indicator of the severity of damage in a given area, particularly the damage to buried lifelines. The thickness of liquefaction fill or natural sand deposit is easily used in geographical information systems, providing an excellent vehicle for assessing urban hazards, microzoning for seismic hazard reduction, and planning for optimal lifeline performance during an earthquake.

Computer simulations of damaged water supply performance during the earthquake are consistent with observations in the field and indicate that graphic modeling of hydraulic networks is sufficiently advanced for effective use in system management and emergency preparations. The computer simulations emphasize the importance of an independent power supply for isolation valves and the substantial effect that hydrant breaks have on water lost from the system.

The events of the earthquake show that flexibility provided in San Francisco by the Portable Water Supply System was of critical importance in controlling and suppressing the fire that erupted in the Marina District. The ability to operate with portable hosing and draft from a variety of water sources, including underground cisterns and fireboats, provided a valuable extra dimension in the city's emergency response.

Finally, I'd like to give a warning: beware the revenge of the infrastructure. We don't have to wait for an earthquake to have a major disaster. I hope the many valuable lessons learned after disasters can be applied to more effectively use our utility supplies and critical resources. Thank you.

Donald Ballantyne, Kennedy/Jenks Consultants

Coming from Seattle, I want to talk about what effect the Loma Prieta earthquake has had in other areas of the country. I have comments on increasing earthquake awareness, water system evaluation and design, and emergency planning.

Millions saw live TV coverage of the Loma Prieta event, which served to increase earthquake awareness. The water and sewer industry in particular had its awareness raised. The Water Pollution Control Federation was having its national conference in San Francisco that week, with many lifeline system owners from across the United States attending. They returned home to significantly influence the implementation of earthquake-mitigation programs in water and wastewater facilities. Moreover, many lifeline system owners sent teams to San Francisco to discuss the impacts of the event with their local counterparts. I believe that the closer one gets to an earthquake, the greater psychological impact it has. This can ultimately turn into the driving force to initiate earthquake-mitigation programs.

The NEHRP program identified Seattle as a target area in 1987. In 1986, there were no lifeline earthquake mitigation programs in the Seattle area. In 1993, every major water and wastewater facility has a program in place, as do many of the moderate-size utilities. This resulted from the synergy of the NEHRP program's provision to develop basic seismological data in the northwest and the focus drawn from the Loma Prieta earthquake, which demonstrated what the effects of an event could be.

Pipeline failures are concentrated in areas where liquefaction-induced permanent ground deformation occurs and can result in draining water storage tanks holding water needed for fire suppression. The old cast-iron pipe along the San Lorenzo River in Santa Cruz failed, which drained reservoirs. Service was lost to the city's two hospitals, and fire-protection capabilities were lost in those pressure zones. Luckily, fire was not a problem as there was no wind that evening. Power was not available for pumping to refill tanks for a number of days. This refocuses thinking on the hazards of liquefaction and ground deformation to vulnerable pipeline systems. System-control measures to maintain system function, and possibly dedicated fire-protection systems, are potential mitigation alternatives.

With such a large inventory of pipe in the ground and the high cost of replacement, a more reasonable approach may be isolating damaged portions of the system—either the reservoirs themselves, pipelines crossing faults, or areas that are geotechnically unstable.

Emergency planning and plan exercise is crucial. Historically, emergency planning has had a low priority. The Loma Prieta event demonstrated the need. All responsible organizations should be involved in emergency planning for their particular service. A few points particularly relevant to the water industry in-

clude provision for emergency power, pumps, chlorinators, and repair materials. Statewide or regional mutual aid programs are very worthwhile and should be improved.

Charles R. Roberts, Executive Director, Port Of Oakland

Good morning. I am going to discuss this from the angle of implementing repair activities and some administrative issues that followed the earthquake.

There is not much information available about how to repair the damage, how to get a facility back into operation quickly, or how to repair so that a facility won't fail in the next event.

We had developed a reporting system that was activated automatically with a 5.0 event on the Hayward fault. In the event of an earthquake, supervisors informed the civil, mechanical, and electrical engineers to inspect and report back. We knew within hours where we needed to do emergency work and where we were out of business.

The next step is to have a plan to assemble a work force, establish control centers, and initiate a multichannel communications system and a pre-authorized chain of authority. The system developed by the Port of Oakland was satisfactory, except more understanding of the chain of authority needed to be emphasized.

Finally, time reporting systems, damage categories, and financial recording in accordance with and parallel to Federal Emergency Management Agency's procedures and policies must be set up ahead of time.

For implementation, we now need to take these lessons learned to explain how to repair the subsidence problems so that they will not happen again and how to repair major concrete structures standing on long piles with heavy weights.

Steve Phillips, Pg&E

Good morning. The most important item to stress is the need to be prepared.

In 1987, PG&E developed a corporate emergency-operations-center concept designed to deal with system-wide emergencies such as an earthquake. We did go through a mock emergency exercise—using a scenario of a 7.0 earthquake on the Hayward fault.

There have been other programs—in 1984 a formal gas pipeline replacement program was developed to look at several categories of pipeline that needed to be replaced on a systematic basis (cast-iron, pre-1930 steel-distribution facilities and certain types of older transmission lines with sub-standard welds).

Although begun in 1984 and funded at $80 million, this was a 20 to 30 year program. Almost all of the leakage occurring in the PG&E system was on facilities that fell into the pipeline replacement category. Distribution systems in the Marina District, Los Gatos, and Watsonville had to be replaced. Since the Loma Prieta earthquake, a seismic risk factor (soils and proximity to fault zones) has been included into the formula for prioritizing the pipe replacement schedule.

In the mid-1980s, PG&E began to do seismic analysis of gas facilities using a pipeline scenario to see how they would fare in an event. The study had not been completed by 1989. There was no damage in those facilities—primarily because of the location and duration of the earthquake—, and PG&E was able to make the necessary modifications (which were fairly inexpensive).

On the electric side, there was a similar program also begun in the mid-1980s. The Loma Prieta earthquake validated most of the assumptions made in that study. For example, there was no substation damage at the 115-kV and below level; there was the most damage at 500-kV substations; and there was substantial but less damage at 230-kV substations. At PG&E, we also predicted we would have no damage to control room facilities. That is exactly what happened during the Loma Prieta earthquake. A prioritized replacement program was already in place for most of the targeted equipment in those facilities. Although PG&E was not completely ready when the earthquake hit, we were positioned to be able to move forward rapidly to reduce the seismic risk when the situation did occur.

The Loma Prieta earthquake struck the San Francisco area on October 17, 1989, causing 63 deaths and $10 billion worth of damage. This book reviews existing research on the Loma Prieta quake and draws from it practical lessons that could be applied to other earthquake-prone areas of the country. The volume contains seven keynote papers presented at a symposium on the earthquake and includes an overview written by the committee offering recommendations to improve seismic safety and earthquake awareness in parts of the country susceptible to earthquakes.

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Engineering Laboratory

Earthquake loma prieta california 1989.

Earthquake Loma Prieta California 1989 The Loma Prieta earthquake was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989, at 5:04 p.m. local time. Caused by a slip along the San Andreas Fault, the quake lasted 10–15 seconds and measured 6.9 on the moment magnitude scale, or 6.9 on the open-ended Richter Scale. The quake killed 63 people throughout northern California, injured 3,757 and left some 3,000-12,000 people homeless.

The highest number of fatalities, 42, occurred in the City of Oakland because of the failure of the Cypress Street Viaduct on the Nimitz Freeway (Interstate 880), where a double-deck portion of the freeway collapsed, crushing the cars on the lower deck. One 50-foot (15 m) section of the San Francisco – Oakland Bay Bridge also collapsed, leading to the single fatality on the bridge. Three people were killed in the collapse of the Pacific Garden Mall in Santa Cruz, and five people were killed in the collapse of a brick wall on Bluxome Street in San Francisco.

On October 18, 1989, the U.S. Senate Committee on Commerce, Science and Transportation and the U.S. House of Representatives Committee on Science, Space and Technology requested the National Institute of Standards and Technology (NIST) investigate earthquake damage including the elevated section of Interstate 880 and the other bridge structures. The team traveled to the San Francisco area and carried out its investigation during the period of October 18-26, 1989.

See the NIST report, " Performance of Structures During the Loma Prieta Earthquake of October 17, 1989 ," for more information.

NBC Bay Area

Loma Prieta: Looking Back on the Earthquake 33 Years Later

The epicenter of the earthquake was located roughly nine miles northeast of santa cruz, by nbc bay area staff • published october 17, 2022 • updated on october 18, 2022 at 9:00 am.

The Loma Prieta Earthquake jolted the Bay Area and beyond 33 years ago Monday, shaking buildings from their foundations, flattening a stretch of freeway in Oakland and dislodging a section of the Bay Bridge.

Take a look back at the devastating earthquake below.

When and where was the Loma Prieta Earthquake?

The earthquake struck at 5:04 p.m. on Oct. 17, 1989.

Get a weekly recap of the latest San Francisco Bay Area housing news. Sign up for NBC Bay Area’s Housing Deconstructed newsletter.

Baseball fans across the Bay Area were gearing up to watch Game 3 of the World Series between the San Francisco Giants and Oakland Athletics when the quake struck on the San Andreas Fault near Loma Prieta peak in the Santa Cruz Mountains.

The epicenter was located roughly nine miles northeast of Santa Cruz and 60 miles south-southeast of San Francisco, according to the U.S. Geological Survey.

Shaking was said to have lasted for about 15 to 20 seconds, and people as far away as San Diego and western Nevada reportedly felt it, according to the California Department of Conservation.

Aftermath: The Loma Prieta Earthquake

What was the magnitude of the loma prieta earthquake.

Loma Prieta was a 6.9 magnitude quake.

Loma Prieta Earthquake causalities

The earthquake left 63 people dead and injured more than 3,700 others.

Loma Prieta Earthquake damage

The quake damaged an estimated 18,300 houses, according to the conservation department. Another 963 were destroyed. The shaking also damaged nearly 2,600 businesses and wiped out 147. 

Tremors caused a portion of the upper deck of the Bay Bridge to collapse onto the lower deck, leaving the vital transportation artery unusable for about one month. The upper deck of the nearby Cypress Freeway in Oakland also came crashing down in an instant, crushing cars on the freeway's lower level. Forty-two people were killed.

Over in San Francisco, the soft soil of the Marina District gave way. Homes toppled, gas lines ruptured and blazes ignited.

Brick buildings in downtown Santa Cruz crumpled.

Bay Area Revelations: Loma Prieta Earthquake, 30 Years Later

If you'd like to learn more about the Loma Prieta Earthquake, watch the full Bay Area Revelations episode . It includes interviews with survivors, first responders and unsung heroes who experienced one of the strongest earthquakes to rattle the region in decades.

san francisco earthquake 1989 case study

Bay Area Scientists Finding Ways to Predict Earthquakes

san francisco earthquake 1989 case study

Bay Area Geologists Dig Deep to Learn More About Earthquakes

san francisco earthquake 1989 case study

Why the 1989 San Francisco Quake Was So Disastrous

The 1989 San Francisco earthquake delivered a myriad of deadly disasters, all unfolding at the same time: from a collapsed freeway to deadly fires in the city's historic marina. (04:03)

  • International edition
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In a 17 October 1989 photo, a California highway patrol officer checks the damage to cars that fell when the upper deck of the Bay Bridge collapsed onto the lower deck after the Loma Prieta earthquake in San Francisco.

Thirty years after devastating quake, is San Francisco ready for the next?

The 6.9-magnitude Loma Prieta quake killed 63 in 1989. Decades later, the Bay Area is still plagued by structural threats and flammable fuels

On the afternoon of 17 October 1989, a 6.9-magnitude earthquake rocked the San Francisco Bay Area, killing 63 people and causing $13bn in damages as it toppled a chunk of the Bay Bridge, collapsed a section of freeway in Oakland, and crumbled thousands of buildings from San Francisco to Santa Cruz.

Thirty years later, California will launch an earthquake early warning app, the first to cover the whole state, developed by UC Berkeley and the California Office of Emergency Services. The decades since the Loma Prieta quake have been remarkably quiet – yet it’s not a matter of if, but when, the next large earthquake will rattle the Bay Area, and the consequences will undoubtedly be severe.

There are multiple faults to worry about in the Bay: the infamous San Andreas is a system, with branches that run up the San Francisco peninsula, along the East Bay foothills through Oakland and Berkeley and further inland through Dublin and Walnut Creek.

Just this week, a 4.5-magnitude quake with an epicenter in the Pleasant Hill area shook the region.

An antenna to send data stands on a rise above an earthquake monitoring well, right, powered by a solar electric panel, lower left, as scientists from the US Geological Survey set up an earthquake monitoring station on the San Andreas fault.

In the case of a major earthquake, experts are particularly worried that “ground failures” will cause widespread structural damage in many parts of the region built on landfill and sand. The California Geological Survey’s most recent map of earthquake hazards shows huge swaths of the inner Bay Area are in “liquefaction zones”, meaning that during a major earthquake, the ground could be shaken so violently that it would very temporarily soften into jelly.

“People love to ask the question: is X place prepared for X disaster? Is California prepared for the next earthquake? The answer to that question, 99.99% of the time, is no,” said Dr Samantha Montano, assistant professor of emergency management and disaster science at the University of Nebraska Omaha. “The way we think about preparedness is really kind of weird. When we talk about it day to day: do you have an emergency kit, yes or no? Just because you have that doesn’t mean you’re prepared for an earthquake – there’s a lot more going into that.”

For any community facing a potential wide-scale disaster, the preparation is twofold: mitigating risk and preparing for the inevitable management of the emergency.

While newer, stricter building codes put in place after Loma Prieta have required more quake-resilient construction, thousands of buildings in the Bay Area were built using old, shaky standards. Oakland passed an ordinance in 2019 requiring owners of vulnerable apartments to retrofit their structures. In San Francisco, where retrofits were due to be completed in 2018, about three-quarters of susceptible units have been quake-prepped.

Politicians in Berkeley cited earthquake risk as one motivator for moving to ban natural gas hook-ups in new buildings earlier this year.

Officials and others evacuate a man, Erick Carlson, from the Cypress section of Highway 17, now called Interstate 880, in Oakland, California, following the Loma Prieta earthquake.

“We have basically allowed ourselves to pump a toxic flammable greenhouse gas producing an expensive liquid into our homes across earthquake fault lines,” the Berkeley city councilmember Kate Harrison said at the time. “It will seem crazy in 100 years. We can see that this is a dangerous situation.”

The East Bay had perhaps a little taste of that danger earlier this week: following the mid-sized East Bay quake, two of the area’s five refineries shut down due to the “upset” and their built-up gasses flared.

Later, on Tuesday, a NuStar energy fuel storage facility suffered an explosion and large fire, leading many to speculate the earthquake had triggered the accident. A spokesperson could not confirm the cause of the explosion, which some in the area said felt like yet another earthquake.

“We want local governments to really be taking the lead and making sure not only that there’s a plan for the city’s government but also that they’re integrating the plans with communities and businesses – particularly businesses like refineries, where there could be an added hazards,” said Montano.

#BREAKING : WOW! You can see the tank's top being blown off during this giant explosion at a NuStar refinery in Contra Costa County. According to fire officials, 3 large tanks of ethanol are burning. @kron4news — Amy Larson (@AmyLarson25) October 15, 2019

Environmental justice activists in the East Bay city of Richmond cite this kind of risk in the bigger quakes to come.

“When the Hayward fault shifts, and we have that earthquake, the reality is, large portions of the Chevron refinery are built on landfill,” said Andrés Soto, an organizer with Communities for a Better Environment in Richmond. “And despite the best assurances from Chevron about how they’ve secured their refinery in the event of an earthquake, nature seems to have a way of conquering man-made structures.”

A transition away from the fossil fuels that in turn contribute to several other impending California environmental disasters could help make the Bay Area more resilient when the big one inevitably hits.

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By James Barron

  • Oct. 18, 1989


A devastating earthquake rocked the San Francisco Bay area at rush hour last night, killing at least 200 people, collapsing a mile-long span of an Interstate highway and wrecking part the Bay Bridge to Oakland.

The earthquake, which rumbled along the San Andreas Fault, was the second deadliest in United States history after the 1906 San Francisco earthquake and fire that killed more than 700 people. It started fires throughout San Francisco, Oakland and Berkeley and in the mountain areas near Santa Cruz.

It also forced the cancellation of the third game of the World Series and the evacuation of thousands of spectators from Candlestick Park.

Water, electricity, communication and transportation were knocked out in the nation's fourth largest metropolitan area, leaving officials to guess at the scope of the damage and residents to wander darkened streets, aware that they were in the middle of one of the worst catastrophes of their lives but unable to judge its extent. With little information except sketchy reports from transistor radios, they gathered in ones and twos on their porches and in larger numbers outside bars and hotels. There was a sense that they were surrounded by great damage, yet their isolation from the outside world made it impossible to know that so much had been destroyed in such a short time.

''This is just a devastating, terrible, terrible situation beyond everybody's imagination,'' said Marty Boyer, the public information officer for Alameda County.

Lieut. Gov. Leo McCarthy said the most extensive damage appeared to be south and east of San Francisco. He said he expected that states of emergency would be declared in Santa Clara, Alameda and Contra Costa counties. 200 Are Crushed in Cars The greatest loss of life appeared to have occurred on Interstate Highway 880 in Oakland, when a section of an upper roadway collapsed onto the lower section, crushing at least 200 people in their cars.

In San Francisco, Mayor Art Agnos said eight deaths had been reported, five from buildings collapsing on cars, and three in a fire in the Marina section. The California Highway Patrol said six people were killed when part of a shopping mall collapsed in Santa Cruz. At least two bridges there collapsed and other highways swayed and buckled in the quake, but there were no immediate reports of injuries.

The earthquake rumbled through the area at 5:04 P.M., (8:04 P.M. Eastern time) and registered 6.9 on the Richter scale. It was centered near Hollister, 80 miles southeast of San Francisco in San Benito County, and shook buildings as far as 200 miles away. People Scramble to Safety

Some people escaped from buildings seconds before the structures shook and collapsed in a hail of rubble. ''It was like a movie, happening behind us,'' said Robert Northrup, who was leaving a meeting in Santa Cruz when the building fell. ''It was absolutley like a Spielberg movie, like ''Indiana Jones.'''

John F. Melvin, a guest at the Four Seasons Clift Hotel in San Francisco, said he had been on the telephone to New York when the room started to shudder. ''It was like riding on a New York City subway car,'' he said. He tried to dive under the bed but ended up a table, where he stayed until the swaying subsided.

Mike Krukow, a pitcher for the San Francisco Giants, said, ''It was an unbelieveable thing.'' He was on the field awaiting the start of the World Series game when vibrations began. ''The light towers were shaking,'' he said. ''I was stunned, stunned.''

The game was scheduled to begin in 16 minutes when the earthquake struck. ABC News and the Cable News Network reported that some of the 58,000 fans were injured as they rushed to the exits. Fans said they saw pieces of cracked concrete on the walkways outside the Candlestick Park, but the stadium itself did not appear to have been seriously damaged.

Baseball Commissioner Fay Vincent is to meet with other officials this morning to decide on when to reschedule the game between the San Francisco Giants and Oakland Athletics. Cars Dangle on Broken Bridge

A 30-foot section section of the upper deck of the San Francisco-Oakland Bay Bridge caved in. Witnesses said that at least two cars were dangling between the upper and lower levels.

In Oakland, where the Interstate highway collapsed, witnesses said the concrete and steel supports of the double-decked, elevated road crumpled.

''The freeway was fairly crowded when it collapsed,'' said Rick Andreotti, an Oakland police spokesman at a makeshift rescue center beneath the collapsed roadway. ''It's not a matter of just getting to the cars, it's a matter of cutting the cars open.''

He said rescuers believed that some of the the people in cars sandwiched between the two tiers were still alive. Television cameras zoomed in on two firefighters trying to rescue a 7-year-old boy trapped in the back seat of his parents' car. Witnesses said his 9-year-old sister had been pulled from the vehicle and taken to a hospital. Their parents were killed, witnesses said.

Rescuers said it might take days to bring in the heavy equipment needed to clear the wreckage of the highway.

Five other freeways in the region were closed because of damage, including the curving overpasses leading into downtown San Francisco from the airport. Airport Damaged and Closed

At the airport, people waiting to board airplanes were showered with falling plaster before they were evacuated. A Federal Aviation Administration spokesman in Washington, Robert Buckhorn, said the airport was closed at 6:30 P.M. At least one major runway was damaged, and the control tower had to be evacuated because of structural damage. The controllers moved to a temporary location nearby, Mr. Buckhorn said.

The top two floors of a hotel near the airport collapsed, and in downtown San Francisco, bricks tumbled off buildings as the quake rumbled through.

Jane Gross, The New York Times bureau chief in San Francisco, was walking in a building in downtown San Francisco when the quake hit. Windows above her shattered, and the glass rained down on the street as she ran for cover.

Richard Bishop, an engineer who was driving to San Francisco from Sunnyvale, Calif., said he saw overhead lights and power poles swinging back and forth like palm trees in the breeze.

In Union Square, the heart of San Francisco's shopping and hotel district, the glass in half of the front windows of the I. Magnin department store shattered, covering the sidewalks with diamondlike crystals. Medical workers were bandaging the heads and hands of shoppers hit by the falling glass. One woman was seriously cut when she protected her wheelchair-bound brother, who has cerebral palsy, with her own body.

In the Fisherman's Wharf section along San Francisco Bay, chunks of broken asphalt jutting out of the street. ''The street had just exploded out of the ground, like someone had hit it with a giant fist from underneath,'' said Andrew Lee, who works in a record store there.

Hundreds of people fled from the subway system, the Bay Area Rapid Transit, before it was shut down at 6:30.

The hardest hit section of San Francisco seemed to be the Marina district, a fashionable area that was built on landfill brought in to make space for the Pan-American Pacific Exposition of 1905. Several apartment buildings there wobbled and collapsed onto parked cars. There were also a number of small fires that burned unattended while firefighters struggled to contain the biggest blazes. Some of the firefighters arrived by boat, squeezing past yachts docked near the fallen, burning buildings.

Across the bay in Berkeley, a fire was burning near the library at University of California. The earthquake blacked out 75 percent of the city and caused isolated fires, witnesses said. Residents were told they would have no water for 72 hours.

Some Berkeley shopkeepers were worried about looting. One pizzeria owner stood in front of his storefront with a sawed-off shotgun. ''I'm protecting my property,'' he said.

Hours after the quake, state disaster officials were meeting in Sacramento with the Red Cross and the state police. The National Guard was put on telephone alert, with thousands of Guardsmen standing by for orders. President Offers U.S. Help

In Washington, President Bush said the Federal Government was prepared to send help to California. The President said he was sending Secretary of Transportation Samuel K. Skinner there to assess the damage. Late last night, Vice President Dan Quayle, who had been in San Diego earlier yesterday, said he would tour San Francisco early today, along with his wife and Mr. Skinner.

Army troops from a training center at Fort Ord, near Monterey, Calif., were sent in by helicopter to help the police.

''I will tell you as a native Californian, that was the wildest, longest earthquake I have ever ridden,'' Greg Cook, 40 years old, told The Associated Press. Mr. Cook, a spokesman for the Nuclear Regulatory Commission in Walnut Creek, 25 miles east of Oakland, said there were no reports of damage to any of the state's six nuclear reactors.

One man told NBC News that he was walking next to a building when the earth started to tremble.

''I saw dust falling,'' he said. ''I saw buildings shake. People said stay away from the glass. People said go close to the glass. I didn't know what to do. It's hard to believe a big building could move like that.''

San Francisco's famous cable cars ground to a halt at the first temblor, and within five minutes, police officers and firefighters were blocking streets that were littered with debris. As people realized that they were in the middle of an electric blackout, they gathered around transistor radios that were propped on the tops of cars and listened to KCBS, a local all-news radio station.

The station alternated between reporting what was going on and taking calls from listeners. The voices, coming over tinny transister radio speakers, reported disasters great and small from all over the Bay area. Callers Tell Their Stories

A woman reported a collapsed building in the Castone Valley. A man called in to say his car had been flipped as if it were a toy. No lights except the lights of cars inching their way through the city could be seen. Above, the sky was pitch black except for the lighted word ''Goodyear'' on the side of the blimp that had come to hover over the World Series game and instead hung over on a disaster.

At a nine-story municpal garage in North Beach, motorists walked up the curling ramps to get their cars; the elevators had stopped.

At Presbyterian Hospital on Clay Street near Sacramento Street in the lower Pacific Heights-Fillmore section, doctors, nurses and patients ran out onto the street as the building shook in the quake. Shoppers along Fillmore Street also streamed out onto the street, standing in small groups, reassuring each other. Someone yelled, ''I made it through the big one.'' Lines Await Batteries and Phones

Outside a Walgreens discount store in Chinatown at 6 P.M., 50 people were lined up to buy batteries and other provisions. At almost every pay telephone, long lines of people stood waiting for a chance to call home.

Everywhere people seemed in a state of shock. A steady stream of people came in to the Central Police Station on Vallejo Street near Stockton Street in the North Beach section. Most of them were neither distraught nor injured. The majority were from the East Bay and wanted to know there was any way to get home because they had heard the bridges and freeways were closed. They were told that there was no way, at least not before dawn today.

About 360,000 people normally commute in and out of San Francisco in the evening rush.

People reported gas leaks in many parts of San Francisco. Officials of Pacific Gas & Electric told local television stations that between 500,000 and 1 million customers had lost power.

Saturday, Late Edition - Final Articles on Wednesday and Thursday about the California earthquake misstated the history of the Marina district of San Francisco. The district was built on landfill created to make space for the Panama-Pacific International Exposition of 1915, not the Pan-American Pacific Exposition of 1905.

How we handle corrections

America’s Vulnerable Water Systems

Paying the Price: Siemens and other corporations vowed to fix water woes in Mississippi and save cities across the state millions. The deals racked up debt instead , leaving many worse off than before.

A Tax on Groundwater: While American farmers elsewhere can freely pump the water beneath their land, growers in California’s Pajaro Valley pay hefty fees. Experts say the approach is a case study in how to save a vital resource .

A Diet Feeding a Crisis: America’s dietary shift toward far more chicken and cheese in recent decades has taken a major toll on underground water supplies .

First Come, First Served?: As the world warms, California is re-examining claims to its water that are  based on a cherished frontier principle and have gone unchallenged for generations.

Jets Powered by Corn: America’s airlines want to replace jet fuel with ethanol to fight global warming. That would require lots of corn, and lots of water .

Blocking Change :  Groundwater is dwindling in much of the United States, but only a powerful few have a say over its use. Meet the people fighting conservation efforts .


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  • Earthquake Case Study: 1989 San Francisco Earthquake

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1989 San Fransicso Earthquake - Case Study

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Niall Watts                10B

1989 San Francisco Earthquake

The Loma Prieta Earthquake which took place on October 17th, 1989 in the greater San Francisco Bay Area, California, caused fifty seven deaths directly and another six more were caused indirectly by the temblor, excluding the fact that there were another 3,757 injuries.           The earthquake occurred at 5:04 PM local time and was recorded at a scale of 6.9 on the Moment magnitude scale. The earthquake lasted for a total time of fifteen seconds. It came during the 1989 World Series, when Bay Area's two Major League Baseball teams, the Oakland Athletics and San Francisco Giants were competing against each other .

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Aftershocks took place over the following 36 hours. It also took place over rush hour in the city. The   San Andres fault ruptured bilaterally, that is in two directions, from the centre of the fault line, causing a relatively short shock. If the fault had ruptured unilaterally, along the entire fault line, the shock would have lasted for almost double the time.

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The underlying geology of California causes most of its earthquakes. Much of San Francisco is based on clay, some areas are built on reclaimed soft soil, e.g. the Marina district was built on reclaimed marshland in 1915. During the past years, the Santa Cruz Mountains have moved 6 ft northwards along a 25 mile section of the San Andres fault.

The problem comes when the quake occurs. The hard rock of the area provides resistance to the shock waves, and they are reduced in intensity. The clays and soft soils magnify the wave’s power, and can cause them to behave lick quicksand, an effect known as liquefaction. Under this, buildings can sink, intact, under their own weight. What made the earthquake even worse, was that the quake was predicted and the areas which suffered most were known to be at risk, and yet nothing was done.

All of the following events were caused by the earthquake of ’89:

  • For some time, TV was the main means of communicating with the outside world.
  • Local power supplies were cut, and the government emergency radio system had failed.
  • People stayed at home, and isolated themselves.
  • Relief efforts for the “Bay Area” were a national response.
  • Media takes some responsibility for public education.
  • The government were slow to respond. The media respond much faster.
  • Total economic damage of around $10 billion.
  • 42 died in Oakland, 60 miles from the epicentre. Are there were 400 injuries from the Cypress structure alone.
  • 59 water mains burst, and over 100 gas mains were ruptured.
  • 10,000 were left homeless, 63 died.
  • The Nimitz highway, and Cypress structure, and sections of the Bay Bridge collapsed, due to structural failure. They were subject to ten times the amount of force for which they were designed

1989 San Fransicso Earthquake - Case Study

Document Details

  • Word Count 472
  • Page Count 2
  • Subject Geography

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    On October 17, 1989, a magnitude 6.9 earthquake hit the San Francisco Bay Area, killing 67 people and causing more than $5 billion in damages. Despite the fact that the disaster was one of...

  3. Loma Prieta Earthquake Professional Papers Completed

    The four Loma Prieta Earthquake Professional Papers, which were published as multiple chapters, comprehensively document the magnitude 6.9 earthquake in California that shook the San Francisco and Monterey Bay regions on October 17, 1989. They contain almost 3000 pages written by 401 investigators of the earthquake. The investigations were funded by a special Congressional appropriation to the ...

  4. San Francisco earthquake of 1989

    San Francisco earthquake of 1989, major earthquake that struck the San Francisco Bay Area, California, U.S., on October 17, 1989, and caused 63 deaths, nearly 3,800 injuries, and an estimated $6 billion in property damage.

  5. Oct 17, 1989 CE: Loma Prieta Earthquake

    On October 17, 1989, the San Francisco Bay area of the United States was jolted by the Loma Prieta earthquake. The quake's epicenter was near Loma Prieta Peak in the Santa Cruz Mountains. The magnitude 6.9 quake was the most powerful the state had experienced in several years. The Loma Prieta earthquake was triggered by the mighty San Andreas ...

  6. 3. Buildings

    The Loma Prieta earthquake struck the San Francisco area on October 17, 1989, causing 63 deaths and $10 billion worth of damage. This book reviews existing research on the Loma Prieta quake and draws from it practical lessons that could be applied to other earthquake-prone areas of the country.

  7. 1989 Loma Prieta earthquake

    The 1989 Loma Prieta earthquake occurred on California's Central Coast on October 17 at 5:04 p.m. local time. The shock was centered in The Forest of Nisene Marks State Park in Santa Cruz County, approximately 10 mi (16 km) northeast of Santa Cruz on a section of the San Andreas Fault System and was named for the nearby Loma Prieta Peak in the Santa Cruz Mountains.

  8. Understanding the 1989 Loma Prieta earthquake in an urban context

    November 7, 2014. Source: Geological Society of America. Summary: In an urban environment, the effect of a major earthquake such as the 17 Oct. 1989 Loma Prieta event can be pieced together by the ...

  9. 5. Lifeline Perspective

    While recent funding levels for lifeline earthquake studies are an average of 11 percent of the total amount spent, this number may increase in the post-earthquake environment. ... One of the case studies used in these evaluations was the Loma Prieta earthquake. ... 1989 Loma Prieta Earthquake in San Francisco. Technical Report NCEER-90-0001 ...

  10. The Loma Prieta, California, Earthquake of October 17, 1989

    The great 1906 San Francisco earthquake (M S =8.2-8.3) generated more than 10,000 landslides throughout an area of 32,000 ... Evaluation of coseismic ground cracking accompanying the earthquake: Trenching studies and case histories, by Jeffrey M. Nolan and Gerald E. Weber ... Plate 1, Landslides and ground cracks generated by the 1989 Loma ...

  11. The 1989 Loma Prieta Earthquake

    Only two have occurred since the San Francisco earthquake. Several 5.0-plus seismic events in the two years preceding Loma Prieta also served as warnings. There is still a 50 percent chance for one or more magnitude 7.0 earthquakes In the San Francisco Bay Area in the next 30 years, and the probability of a repeat of the 1906 quake is significant.

  12. Earthquake Loma Prieta California 1989

    Earthquake Loma Prieta California 1989 The Loma Prieta earthquake was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989, at 5:04 p.m. local time.

  13. Remembering the 1989 Loma Prieta Earthquake, 33 Years Later

    The earthquake struck at 5:04 p.m. on Oct. 17, 1989. Baseball fans across the Bay Area were gearing up to watch Game 3 of the World Series between the San Francisco Giants and Oakland Athletics ...


    17 October 1989: Earthquake hits San Francisco A powerful earthquake has rocked San Francisco killing nine people and injuring hundreds. The number of dead is expected to rise...

  15. The San Francisco area earthquake of 1989 and implications for the

    The Richter magnitude 7.1 October 17, 1989 Loma Prieta (San Francisco) earthquake is the largest to occur near a major North American urban center since the historical 1906 San Francisco magnitude ...

  16. Why the 1989 San Francisco Quake Was So Disastrous

    The 1989 San Francisco earthquake delivered a myriad of deadly disasters, all unfolding at the same time: from a collapsed freeway to deadly fires in the city's historic marina. (04:03)

  17. Thirty years after devastating quake, is San Francisco ready for the

    On the afternoon of 17 October 1989, a 6.9-magnitude earthquake rocked the San Francisco Bay Area, killing 63 people and causing $13bn in damages as it toppled a chunk of the Bay Bridge, collapsed ...

  18. Earthquake in Northern California; Violent Quake Hits Northern

    The earthquake, which rumbled along the San Andreas Fault, was the second deadliest in United States history after the 1906 San Francisco earthquake and fire that killed more than 700 people.


    THE LOMA PRIETA EARTHQUAKE OF OCTOBER 17, 1989 A brief geologic view of what caused the Loma Prieta earthquake and implications for future California earthquakes U.S. Geological Survey WHAT HAPPENED . . . WHAT IS EXPECTED . . . WHAT CAN BE DONE '--rSS^^I -;6AKLAND4:^V SAN FRANCISCO ^.^ pRANCISCO EARTHQUAKE ORIGIN Time: October 17, 1989

  20. Earthquake Case Study: 1989 San Francisco Earthquake

    Earthquake Case Study: 1989 San Francisco Earthquake On 17th October 1989, at 5.04 pm, an earthquake measuring 6.9 on the Richter scale, and lasting only 15 short, but devastating seconds, hit San Francisco (see shake intensity map) The following YouTube video gives an overview of some of the images of the aftermath of the earthquake.

  21. The New Self-Anchored Suspension Bridge of the San Francisco Bay Bridge

    The October 17, 1989, M w 6.9 Loma Prieta earthquake (LPE) disrupted large areas of Northern California. Approximately 100 km away from the epicenter of the earthquake, a segment of the upper deck of the old truss bridge spanning between Treasure Island and Yerba Buena Island and East Bay (including Oakland) as part of the San Francisco-Oakland Bay Bridge (SFOBB) system fell onto its lower deck.

  22. Earthquake Case Study; San Francisco Earthquake 1989

    A report lists 27 buildings as unsafe. Only 3 have been made safe in recent times. · Office of Emergency Services/Fairmont Hospital - very near the fault, and major nerve centre for response co-ordination in the event of a quake. If a similar quake hit the Haywood fault, then 8000 would die, 11000 in San Francisco.

  23. 1989 San Fransicso Earthquake

    The Loma Prieta Earthquake which took place on October 17th, 1989 in the greater San Francisco Bay Area, California, caused fifty seven deaths directly and another six more were caused indirectly by the temblor, excluding the fact that there were another 3,757 injuries.