Transient Deformation in Guerrero, Mexico

墨西哥格雷罗州的瞬态变形

• 批准号: 0609646
• 负责人: Kristine Larson
• 金额: $ 18.89万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609646&HistoricalAwards=false
• 关键词: Transient; Deformation; Guerrero; Mexico

This study combines geodesy, seismology, and numerical models to elucidate the origin and nature of aseismic transients and their impact on seismic hazard in the Mexican state of Guerrero and in other subduction zones. The study area encompasses a ~200 km segment of the Cocos-North America plate boundary. The last great earthquake in the northwest section of region occurred in 1911. It has been estimated that if the Guerrero gap were to rupture, its magnitude would exceed Mw 8. GPS measurements have been critical in establishing the widespread existence of aseismic (transient) slip events in subduction zones. More recently, seismic tremor studies have been correlated with aseismic slip events. The seismic data have greater resolution of the location and propagation of transients, while GPS continues to constrain their moment release. Both geodesy and seismology will be needed to understand the source and periodicity of transients and how they relate to the mechanics of the subduction process throughout the earthquake cycle.CU began the Guerrero GPS project in 1997 to measure/model crustal deformation rates and assess seismic hazard in the region. The National Autonomous University of Mexico (UNAM) faculty and students have been partners in this project since its inception. There are currently 10 GPS receivers operating in Guerrero as the result of this collaboration. Using these continuous GPS installations and earlier campaign data it has been demonstrated that three very large transients have occurred in Guerrero in the last decade. The PIs intend to improve and maintain GPS instrumentation, improve and distribute position estimates, and model the GPS data. Broadband seismic data will be collected in Guerrero by Caltech and UNAM during this project period, potentially allowing for tremor detection. A collaboration with a group at Harvard will allow comparison of geodetic and seismic observations with three-dimensional numerical models that includes temperature dependence, rate and state friction, and pore pressure effects.

这项研究结合大地测量学、地震学和数值模型来阐明无地震瞬变的起源和性质，以及它们对墨西哥格雷罗州和其他俯冲带地震灾害的影响。研究区包括科科斯-北美板块边界约200公里的一段。西北地区上一次大地震发生在1911年。据估计，如果格雷罗缺口破裂，其震级将超过8兆瓦。GPS测量对于证实俯冲带普遍存在无地震(瞬时)滑动事件至关重要。最近，地震震动研究已经与无地震滑动事件相关联。地震数据对瞬变的位置和传播有更高的分辨率，而GPS继续限制它们的时刻释放。需要大地测量学和地震学来了解瞬变的来源和周期，以及它们与整个地震周期中俯冲过程的机制之间的关系。加州大学于1997年开始了格雷罗全球定位系统项目，以测量/模拟地壳形变速率并评估该地区的地震危险。墨西哥国立自治大学(UNAM)的教职员工和学生自项目开始以来一直是该项目的合作伙伴。由于这种合作，目前有10个全球定位系统接收器在格雷罗州运作。使用这些连续的GPS装置和早期的竞选数据，已经证明格雷罗州在过去十年中发生了三次非常大的瞬变。PIS打算改进和维护GPS仪器，改进和分发位置估计，并对GPS数据进行建模。加州理工学院和UNAM将在本项目期间在格雷罗州收集宽带地震数据，从而有可能检测到地震。与哈佛大学的一个团队合作，将可以将大地测量和地震观测与三维数值模型进行比较，其中包括温度依赖、速率和状态摩擦以及孔压效应。