Detailed seismic imaging and monitoring of the subsurface material around the San Jacinto fault zone

圣哈辛托断层带周围地下物质的详细地震成像和监测

基本信息

批准号：
1620601
负责人：
Yehuda Ben-Zion
金额：
$ 25.22万
依托单位：
University of Southern California
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-01 至 2019-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1620601&HistoricalAwards=false
关键词：
Detailed seismic imaging monitoring subsurface

项目摘要

This study develops and uses advanced seismological techniques and continuous waveform data recorded by spatially-dense fault zone arrays around the San Jacinto Fault Zone (SJFZ) in southern California. Analyses of these data provide detailed characterization of (potentially time-dependent) seismic velocities and attenuation coefficients of the shallow crust. To provide benchmarks for the new techniques and understand how seismic properties change with location and depth, the investigators use data recorded by shallow borehole seismometers installed within and adjacent to the fault zone, as well as recordings from regional seismic networks. These results complement models of tomographic studies that typically do not resolve seismic properties in the shallow crust, and allow development of seismic structural models around the SJFZ essentially up to the surface. Knowledge of seismic properties of the shallow crust is particularly relevant to observed ground motion and failure processes. These results may be relevant to numerous other applications including crustal hydrology, geothermal energy, subsurface reservoirs and storage, as well as seismic safety of infrastructure facilities. The analysis methods develop by this research can be used in studies of seismic properties of the subsurface material in other locations. The research uses state-of-the-art data and novel seismic imaging and monitoring techniques to close critical observational gaps. The studies address the following key questions: (1) What are the seismic velocities and attenuation coefficients in the top few hundred meters of the crust at various sections of the SJFZ and at sites that are off the fault? (2) At what stress/strain amplitudes do shallow rocks have nonlinear response and temporal changes of properties in relation to different loading mechanisms and periods (e.g., local and remote earthquakes, tides, and seasonal variations) and location with respect to the fault zone, site condition parameters, and depth? (3) How do amplitudes of temporal changes of seismic properties and recovery timescales produced by various loadings vary in relation to the fault zone, site conditions and depth? (4) Are there fault sections and/or off-fault sites with higher susceptibly to failures (manifested by time-dependent seismic properties), and if they are found, can anomalous properties in these regions be identified that may explain the elevated susceptibility? The studies can augment significantly the available in situ characterization of seismic velocity and attenuation coefficients, nonlinear response and temporal changes of properties in the top few hundred meters of the crust. The results are expected to provide fundamental information that may lead to improved understanding of seismic ground motion (and hence shaking hazard) as well as other applications.

这项研究开发并使用了先进的地震学技术和连续的波形数据，该数据由南加州的San Jacinto断层区（SJFZ）附近的空间密度断层区阵列记录。这些数据的分析提供了（潜在的时间依赖性）地震速度和浅层地壳的衰减系数的详细表征。为了为新技术提供基准，并了解地震特性如何随位置和深度而变化，研究人员使用安装在断层区域内和附近的浅钻孔地震仪记录的数据，以及区域地震网络的记录。这些结果补充了通常无法在浅层地壳中解决地震特性的层析成像研究模型，并允许在SJFZ周围开发地震结构模型基本上是表面。了解浅层地壳的地震特性的知识与观察到的地面运动和故障过程特别相关。这些结果可能与许多其他应用有关，包括地壳水文学，地热能，地下储层和存储以及基础设施的地震安全。这项研究开发的分析方法可用于其他位置地下材料的地震特性的研究。该研究使用最先进的数据以及新型的地震成像和监测技术来弥合关键的观察差距。这些研究解决了以下关键问题：（1）在SJFZ的各个部分以及未经断层的地点，地壳前几百米的地震速度和衰减系数是什么？（2）在什么应力/应变幅度下，浅岩具有非线性响应和与不同的负载机制和周期有关（例如，局部和远程地震，潮汐，潮汐和季节性变化）以及相对于断层区域，现场条件参数和深度的位置的非线性响应和时间变化？（3）各种负载产生的地震特性和恢复时间尺度的时间变化的幅度与断层区域，现场条件和深度相关？（4）是否存在对故障的明显较高（由时间依赖性的地震特性表现出来）的断层部分和/或ORVART部位，如果发现它们，是否可以确定这些区域中的异常特性可以解释升高的易感性？这些研究可以显着增强地震速度和衰减系数，非线性响应以及地壳前几百米的性质的时间变化的可用原位表征。预计结果将提供基本信息，这可能会导致人们对地震地面运动的理解（并因此摇摆危险）以及其他应用。