Study of Postseismic Deformation Due to the 2010 M7.2 El Mayor (Mexico) Earthquake

2010年M7.2 El Mayor（墨西哥）地震震后变形研究

• 批准号: 1053627
• 负责人: Yuri Fialko
• 金额: $ 41.88万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1053627&HistoricalAwards=false
• 关键词: Study; Postseismic; Deformation; Due; 2010

The April 4, 2010, M7.2 El Mayor earthquake on the US-Mexico border was the largest earthquake to strike Southern California in the last 18 years. The main goals of this project are (1) to accurately capture the transient deformation following the earthquake using campaign GPS observations and (2) use precise geodetic observations, including continuous/campaign GPS and InSAR data to identify the physical mechanisms involved in postseismic relaxation. There is a vigorous debate about the nature of coupling between the upper seismogenic crust and the underlying ductile substrate. End-member models of interseismic deformation include ``bottom-up'' loading of crustal faults by localized shear zones in the lower crust (and perhaps upper mantle) and ``top-down'' loading of the viscous substrate by coseismic stress changes. A related question is what rheology best describes rocks below the brittle-ductile transition. Competing views include linear Maxwell, standard linear solid, bi-linear, powerlaw etc. rheologies. These questions have fundamental implications for our understanding of post-earthquake stress changes, delayed triggering of seismicity, and long-term strength of the continental lithosphere. Investigation of postseismic deformation due to the M7.2 El Mayor earthquake is offering new insights into these questions and allowing a robust test of the competing hypotheses.

2010年4月4日发生在美墨边境的埃尔马约尔7.2级地震是过去18年来袭击南加州的最大地震。该项目的主要目标是：（1）利用活动GPS观测准确捕捉地震后的瞬时变形;（2）利用精确的大地测量观测，包括连续/活动GPS和干涉合成孔径雷达数据，查明震后松弛所涉及的物理机制。关于上部孕震地壳和下伏韧性基底之间的耦合性质存在着激烈的争论。震间变形的端元模型包括下地壳（可能还有上地幔）局部剪切带对地壳断层的“自下而上”加载和同震应力变化对粘性基底的“自上而下”加载。一个相关的问题是什么流变学最好地描述了脆性-韧性转变以下的岩石。竞争的观点包括线性麦克斯韦，标准线性固体，双线性，幂律等流变学。这些问题对我们理解地震后应力变化、地震活动的延迟触发和大陆岩石圈的长期强度具有重要意义。由于M7.2埃尔马约尔地震震后变形的调查提供了新的见解，这些问题，并允许一个强大的测试竞争的假设。