The Influence of Critical Reflections on Ground Motions Recorded in San Francisco and Oakland During the 1989 Loma Prieta Earthquake

1989 年洛马普列塔地震期间旧金山和奥克兰记录的临界反射对地面运动的影响

• 批准号: 9011330
• 负责人: Paul Somerville
• 金额: $ 2.94万
• 依托单位: Woodward-Clyde Consultants
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-05-15 至 1991-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9011330&HistoricalAwards=false
• 关键词: Influence; Critical; Reflections; Ground; Motions

This project is part of the NSF/USGS initiative within the National Earthquake Hazard Reduction Program (NEHRP) to investigate the effects of the Loma Prieta earthquake of 17 October 1989. The strong ground motions recorded in the San Francisco Bay Area during the Loma Prieta earthquake exceeded the levels predicted by standard empirical attenuation relations. A preliminary analysis of these records suggests that this may have been a result of critical reflections of the seismic waves from the base of the crust. The objective of this proposal is to perform further analyses and simulations using an expanded data base that includes recordings of other events of the earthquake sequence in order to rigorously test this and other explanations for the large ground motions observed. Evaluating the cause of this observed departure from predicted levels of ground motion has important implications for estimating ground motions from future large earthquakes on the San Andreas and Hayward faults. It also has implications for other regions in the United States such as the Seattle-Portland region where crustal earthquakes having deep focal depths may similarly elevate ground motions to damaging levels at distant locations; and in the Seattle, Los Angeles, Salt Lake City and other regions where basin response effects are expected to be significant.

该项目是国家地震减灾计划 (NEHRP) 内 NSF/USGS 计划的一部分，旨在调查 1989 年 10 月 17 日洛马普列塔地震的影响。洛马普列塔地震期间旧金山湾区记录的强烈地面运动超出了标准经验衰减关系预测的水平。 对这些记录的初步分析表明，这可能是地震波从地壳底部发生临界反射的结果。 该提案的目的是使用扩展的数据库（包括地震序列其他事件的记录）进行进一步的分析和模拟，以便严格测试对观察到的大地面运动的这一解释和其他解释。 评估观察到的地震动预测水平偏离的原因对于估计圣安德烈亚斯断层和海沃德断层未来大地震的地震动具有重要意义。 它还对美国其他地区产生影响，例如西雅图-波特兰地区，在该地区，具有深震源深度的地壳地震可能同样将远处的地面运动提升至破坏性水平；西雅图、洛杉矶、盐湖城等流域响应效应预计将显着的地区。