Deep Arrays for Earthquake Response, San Francisco Bay Area

旧金山湾区地震响应深层阵列

• 批准号: 9016470
• 负责人: Pedro de Alba
• 金额: $ 25.52万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-03-15 至 1993-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9016470&HistoricalAwards=false
• 关键词: Deep; Arrays; Earthquake; Response; San

This action is to support the installation, in collaboration with the U.S. Geological Survey (USGS) - and possible collaboration with the California Division of Mines and Geology (CDMG) - of two deep arrays in the San Francisco Bay area, with the objective of measuring ground motions and the elevation of ground water pressure during the large earthquake that is expected to occur in the San Francisco Bay area. These recordings will provide valuable data for seismological, earthquake engineering and earthquake hazard mitigation studies: these data do not exist at present. Surface measurements from the October 17, 1989 Loma Prieta, California earthquake showed that the apparent amplification of the peak horizontal ground acceleration at deep clay sites was higher by 100% or more than would have been anticipated; yet no measurements in the soil profile showing how amplification progressed between bedrock and the ground surface are available. Nor are data of this type available at other locations for strong-motion earthquakes. There is a significant probability (67% in 30 years) that an earthquake producing greater intensity of motion than the Loma Prieta event will occur in the San Francisco Bay area; it is thus an excellent location to establish a deep accelerometer array to improve prediction capabilities. Sites are being surveyed in the area, and several promising locations have been identified. An advisory panel consisting of eminent researchers and administrators in earthquake hazard mitigation, from major universities in the United States and Canada, and from the USGS and CDMG, will provide advice on the general requirements for the sites and their instrumentation, as well as on the location of instruments to maximize the usefulness of the data recovered. The panel members have expertise in earth science, geotechnical engineering, and field data measurements. The damage caused by the Loma Prieta earthquake, as well as previous major earthquakes worldwide, point to the need to measure two different types of data so as to improve earthquake hazard mitigation methods: The measurement during strong earthquake-induced ground shaking of the amplification of ground motions in deep clay deposits; and the ground motions and the increase in ground water pressure in saturated sands during strong earthquakes. These measurements could be obtained through two separate field arrays, or a combined array at a site which has the appropriate combination of saturated sands and deep clay deposits. The establishment of these arrays follows the recommendations of the September 1988 workshop on "Designated Sites for Geotechnical Experimentation in the United States", and the November 1990 workshop on "Dynamic Soil Properties and Site Characterization". These sites will become designated geotechnical test sites, open to all interested researchers. The sites will be available for research into geotechnical phenomena not associated with earthquakes, but it is expected that the sites chosen will, in general, be more suitable for investigation of the earthquake-induced phenomena discussed.

这一行动是为了支持与美国地质调查局 (USGS) 合作，并可能与加州矿业和地质部门 (CDMG) 合作，在旧金山湾地区安装两个深阵列，目的是测量旧金山湾地区预计将发生的大地震期间的地面运动和地下水压力升高。 这些记录将为地震学、地震工程和地震减灾研究提供有价值的数据：这些数据目前还不存在。 1989 年 10 月 17 日加利福尼亚州洛马普里塔地震的地面测量表明，深层粘土场地的峰值水平地面加速度的明显放大程度比预期高出 100% 或更多；然而，没有任何土壤剖面测量数据可以显示基岩和地表之间的放大过程。 其他地点也没有此类强震地震数据。 旧金山湾地区很有可能（30 年内发生 67%）发生比洛马普列塔事件强度更大的地震；因此，它是建立深层加速度计阵列以提高预测能力的绝佳地点。 正在对该地区进行勘察，并已确定了几个有希望的地点。 由来自美国和加拿大主要大学、USGS 和 CDMG 的地震减灾领域的杰出研究人员和管理人员组成的咨询小组将就场地及其仪器的一般要求以及仪器的位置提供建议，以最大限度地提高恢复数据的有用性。 小组成员拥有地球科学、岩土工程和现场数据测量方面的专业知识。 洛马普列塔地震以及之前世界范围内发生的大地震所造成的损害表明需要测量两种不同类型的数据，以改进地震减灾方法：在强烈地震引起的地面震动期间测量深层粘土沉积物中地面运动的放大；以及强地震期间的地面运动和饱和沙子中地下水压力的增加。这些测量可以通过两个单独的现场阵列或在具有饱和砂和深层粘土沉积物的适当组合的地点的组合阵列来获得。 这些阵列的建立遵循了 1988 年 9 月“美国岩土工程指定场地”研讨会和 1990 年 11 月“动态土壤特性和场地特征”研讨会的建议。 这些地点将成为指定的岩土测试地点，向所有感兴趣的研究人员开放。 这些地点将可用于研究与地震无关的岩土现象，但预计所选地点通常更适合研究所讨论的地震引起的现象。