Collaborative Research: Toward understanding spatio-temporal variations of seismic clusters in different environments

要减轻自然和人为地震造成的破坏性经济和人道主义影响，需要对地震活动模式的量化、诱发地震活动的识别和提高预测能力进行深入研究。在加利福尼亚州和其他在人口稠密地区运营地热、石油和气田的构造地区，人类引发的地震活动带来的风险可能尤其严重，这些地区具有社会基础设施。该项目综合了新的地震群识别/分类技术、物理模型以及来自不同构造环境的高质量地震和大地测量数据，以改善对与大事件和人为地震有关的地震活动的理解。该方法的一个显著特点是在不同的时空能量尺度上对数千个震群进行统一的分析和解释。这些调查将地震活动的动态在几个小时到几十年的时间尺度上进行量化，并在空间上从全球范围的分析扩展到具有高质量数据的选定地区的重点研究。这项研究在全球、区域和地方尺度上建立了一个综合的震群类型数据库，如主要的地震群类型及其基本参数值。所采用的方法本质上是数据驱动的，但它是由地震活动模型提供信息和动机的，这些模型具有不同类型的流变性和载荷，有助于解释结果。观测和理论相结合的研究有助于从基本物理的观测结果中提取基本信息。该项目开发了检测人类诱发地震活动的改进方法，分类目录，建立地震聚集和主要加载机制之间的关系，并可能为跟踪大型地震事件的准备过程提供额外的信号。所开发的工具和结果可以对活动构造环境、油气和地热产区以及两者兼有的地区的地震活动性和地震灾害分析产生重大影响。

Mitigating the devastating economic and humanitarian impact of natural and human-induced earthquakes requires advanced research on quantification of seismicity patterns, identification of induced seismicity, and improved forecasting ability. The risk posed by human-induced seismicity may be especially acute severe in California and other tectonic regions that operate geothermal, oil, and gas fields in highly populated areas with societal infrastructure. This project synthesizes novel earthquake cluster identification/classification techniques, physical modeling, and high-quality earthquake and geodetic data from different tectonic environments toward improved understanding of seismicity in relation to large events and human-induced earthquakes. A distinguishing property of the approach is uniform analysis and interpretation of thousands of earthquake clusters on different space-time-energy scales. The investigations quantify the dynamics of seismicity on time scales of hours to tens of years, and zoom spatially from worldwide analysis to focused studies of selected regions with high-quality data. The research produces a comprehensive database of cluster styles such as dominant earthquake cluster types and values of their essential parameters, at global, regional, and local scales. The employed approach is intrinsically data-driven, but it is informed and motivated by models of seismicity with different types of rheologies and loadings that help interpreting the results. The combined observational and theoretical studies facilitate extracting fundamental information from the observed results on the basic underlying physics. The project develops improved methods for detecting human-induced seismicity, catalog declustering, establishes relations between earthquake clustering and principal loading mechanisms, and may provide additional signals for tracking the preparation process of large seismic events. The developed tools and results can have significant impact on understanding of seismicity and analysis of seismic hazard in active tectonic environments, oil, gas, and geothermal production areas, and regions containing both.