Practical Lessons from the Loma Prieta Earthquake (1994) / Chapter Skim
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Overview: Lessons and Recommendations from the Committee for the Symposium on Practical Lessons from the Loma Prieta Earthquake
Overview: Lessons and Recommendations from the Committee for the Symposium on Practical Lessons from the Loma Prieta Earthquake
Pages 1-18
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From page 1... ...
Within minutes of its occurrence, it was evident that the Loma Prieta earthquake would become an important case study for all interested in earthquake hazard assessment and risk reduction. Because it presented such an obvious opportunity to learn more about earthquake hazards and ways to mitigate their effects, the U.S.
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From page 2... ...
\ Or\\ ·X \\ Salinas ~ \ FIGURE 1 Map showing the location of the October 19, 1989, magnitude 7.1 Loma Prieta earthquake. Arrows show the extent and direction of fault rupture.
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From page 3... ...
older residential construction is vulnerable to failure that can cause extreme personal, social, and economic consequences; · there is urgent need to improve the seismic resistance of unreinforced masonry and nonductile reinforced concrete building and bridge structures; · many of the most successful mitigation efforts were the direct result of state legislation; · practical, problem-focused research is needed to assess the appropriate repair and retrofit procedures for restoring and improving various building types; · emergency response efforts are complicated by existing social conditions, such as homelessness; and · preparedness pays. Why did some sections of the Cypress Street viaduct collapse and not others?
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From page 4... ...
The purpose of this symposium was to understand how to apply the legacy of knowledge left by the Loma Prieta earthquake to reduce the impacts of future earthquakes throughout the United States. To accomplish this task, the symposium committee and participants attempted to understand and translate this knowledge into practical lessons and recommendations that can be implemented by the appropriate government agencies, designers, builders, care-givers, and others responsible for people's well-being and quality of life.
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From page 5... ...
The National Earthquake Hazard Reduction Program must emphasize the application of existing knowledge and the development of new knowledge and must provide incentives for risk reduction activities. EARTH SCIENCES Lesson 3: In the first few hours following the Loma Prieta earthquake, uneven and in some cases inappropriate emergency responses resulted from the inability of emergency-response decision makers to know where the heaviest shaking and greatest damage actually occurred and from undue dependence on news media reports.
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From page 6... ...
Strong crustal reflections resulting from regional geologic structure may have been of particular importance at these large distances. Recommendation: In preparing emergency response plans, communities must recognize, and scientists must emphasize, that seismic hazard is by no means limited to localfaults, nor will significant damage be caused only by "the big one." Data on seismic velocity structure and regional geologic structure, including crustal thickness, are significant in assessing the potentialfor local damaging ground motions from distant events, and should be assessed.
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From page 7... ...
These maps should become an integral part of land-use planning, and the information should be communicated to developers and building owners. Communities having high landslide potential should not be complacent when reviewing the lessons from the Loma Prieta earthquake—what appears to have been successful performance could have turned out to have unacceptable consequences if the earthquake had occurred closer to cities, the shaking had lasted longer, or the ground had been highly saturated.
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From page 8... ...
Recommendation: Placement and compaction using appropriate geotechnical engineering should be mandatory whereverfilled ground is to be used in earthquake-prone areas. Communities having existing fills should evaluate the ability of the fills to withstand stronger shaking than that caused by the Loma Prieta earthquake, and should take remediation steps, if necessary.
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From page 9... ...
Practicing professionals need to develop refined techniques, consistent with the historical behavior of structures, to make such estimates. Lesson 16: There were numerous structures, ranging from residential buildings to multistory facilities, that were seriously damaged in the Loma Prieta earthquake because of design or construction errors that should have been found
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From page 10... ...
Lesson 17: Unreinforced masonry buildings are not only dangerous to building occupants but can be equally dangerous to adjacent buildings and people on sidewalks and in the streets, due to falling debris. Recommendation: Local governments should create mandatory procedures or programs to reduce the seismic hazards associated with unreinforced masonry buildings in all cities that may be exposed to damaging earthquakes.
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From page 11... ...
Recommendation: Gas pipeline vulnerability studies must include the assessment of areas of potential groundfailure, including liquefaction, di~erential settlement, and surface faulting. These hazards should be mitigated by replacing cast iron pipes with modern steel ones and by designing plans for rerouting or rapid repair.
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From page 12... ...
PLANNING AND EMERGENCY RESPONSE Lesson 26: During the response period, there was an urgent need for better coordination among the various levels of government and private sector businesses. Those organizations that had developed and tested realistic earthquake planning scenarios prior to the Loma Prieta earthquake were better prepared than those that had not.
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From page 13... ...
Federal procedures for awarding earthquake recovery funds to state and local governments should require that the federal contribution be used to restore the stricken community to a functioning, viable community that has improved seismic safety. Lesson 29: Pre-existing social problems such as homelessness, housing shortages, tight government budgets, land-use disputes, and inadequate lifelines will be made worse immediately after a destructive earthquake.
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From page 14... ...
Recommendation: Appropriate utilities should incorporate cable slack as a design requirement in order to minimize failure of thefiber-optic communication systems. Lesson 33: In many culturally diverse communities in the Bay Area, the languages and customs were not understood by relief workers after the Loma Prieta earthquake.
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From page 15... ...
Despite efforts by California natural gas companies to educate the public, almost all of the 156,000 customer gas shut-offs following the Loma Prieta earthquake were unnecessary. They were mostly initiated by poor advice from the media immediately after the earthquake.
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From page 16... ...
Earthquake professionals must take note of the factors that motivate building owners and business leaders: improving return on investments, lowering expenses, curtailing losses, and avoiding liability. Lesson 39: The fact that the Loma Prieta earthquake occurred as the third World Series game between San Francisco and Oakland was starting resulted in extensive international media coverage and increased earthquake awareness.
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From page 17... ...
NOTE ON SUPPORTING SOURCES See the 1989 Hearings on the Loma Prieta Earthquake conducted by the California Seismic Safety Council in which numerous examples are described to support Lessons 13 and 16. Other references include: California Seismic Safety Commission, 1991, Loma Prieta's Call to Action, 97 pp., Sacramento; Lew, H.S.
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