GPS measurements and earthquake cycle modeling of the Mexico subduction zone

墨西哥俯冲带的 GPS 测量和地震周期建模

• 批准号: 1114174
• 负责人: Dennis DeMets
• 金额: $ 53.99万
• 依托单位: University of Wisconsin-Madison
• 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: 2011-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1114174&HistoricalAwards=false
• 关键词: GPS; measurements; earthquake; cycle; modeling

This project will continue a long-term GPS-based study of the seismically hazardous Mexico subduction zone (MSZ), where rapid plate convergence rates, the proximity of the trench to the coast, short earthquake recurrence intervals (≈50-100 years), and nearly flat subduction afford exceptional opportunities to measure and model all phases of the subduction earthquake cycle. The proposed work moves beyond their previous work in this region in several important respects. All theMexican investigators who operate significant numbers of GPS stations in mainland Mexico have agreed to collaborate on an integrated study of the MSZ earthquake cycle, making this the first study to integrate GPS observations from the entire 1600-km-long MSZ, where all phases of the earthquake cycle have been recorded two or more times by GPS. They will use GIPSY?s newly available single-station ambiguity-resolution feature and JPL?s new satellite products (due in mid-2011) to reprocess the pooled GPS data from ∼80 continuous stations and more than 100 campaign sites. The expected reductions in the station coordinate noise will permit more detailed studies of episodic transient slip, interseismic strain, and afterslip than were previously possible. The researchers will test and apply a new inverse procedure to estimate and isolate the contributions of interseismic elastic strain, episodic transient slip, coseismic rupture, postseismic fault afterslip, and postseismic viscoelastic rebound to GPS station time series. Specific hypotheses regarding the stationarity and depth limits of transient slip will be tested and viscoelastic modeling will be done to understand present deformation in coastal and interior areas of Mexico. In the Jalisco/Colima region of western Mexico, large subduction thrust earthquakes in 1995 and 2003, fault afterslip triggered by those earthquakes, and recently discovered nonvolcanic tremor offer an exceptional opportunity to determine rigorously where these three processes originate along the subduction interface and what they reveal about the factors that determine downdip changes in the frictional state along a subduction interface. GPS and seismic data from the Michoacan, Guerrero, and Oaxaca segments of the MSZ will be used to study how and whether episodic transient slip in the two regions is connected in space or time, and where this slip occurs relative to the seismogenic zones and nonvolcanic tremor in both regions. The same data will be used to determine the distribution of interseismic coupling and hence seismic hazard along these trench segments. GPS data from the Chiapas trench segment will be used to test for transient slip there and estimate the degree of interseismic locking, toward a better understanding of the cause of the Chiapas seismic gap. Useful output related to hazards will include estimates of interseismic locking rates along most of the earthquake-prone MSZ, assessment of whether transient slip in southern Mexico loads or unloads lower areas of the seismogenic zone, and continuous monitoring of deformation rates on and around Volcan Fuego de Colima, Mexico?s most active volcano. A sub-award to UNAVCO will enable the continued operation and maintenance of the 35 continuous GPS stations built by DeMets and hisMexican collaborators, which constitute one-third of Mexico?s GPS infrastructure. Finally, the project will fund 2 UW graduate students. Outreach presentations to students, faculty, and Mexican government officials will be done by the project participants.

该项目将继续基于GPS的墨西哥俯冲区（MSZ）的长期研究，其中快速板的收敛速率，沟槽到海岸的距离，短地震复发间隔（＆＃8776; 50-100年）以及几乎平坦的俯冲机会，可以衡量和模拟所有层面层面的均匀循环。在几个重要方面，提议的工作超越了他们以前在该地区的工作。所有在墨西哥大陆运营大量GPS站的研究人员都同意合作对MSZ地震周期进行一项综合研究，这使得这项研究是将整个1600公里长的MSZ整合到整个1600公里长的MSZ的研究，在该研究中，地震周期的所有阶段都记录了两次或多次GP。他们将使用Gipsy的新现行单站歧义分辨率功能和JPL的新卫星产品（2011年中期），从＆＃8764; 80连续站和100多个活动网站重新处理了汇总的GPS数据。站点坐标噪声中的预期减少将允许对发作性瞬态滑移，跨震动应变和后滑动后的详细研究。研究人员将测试并采用一种新的反过程来估计和隔离跨界弹性应变，情节性瞬态滑移，coseis震动破裂，后滑动后的后断层和后视粘弹性反弹对GPS电台时间序列的贡献。将测试有关瞬态滑移的平稳性和深度极限的特定假设，并将进行粘弹性建模，以了解墨西哥沿海和内部地区的当前变形。在墨西哥西部的哈利斯科/科利马地区，1995年和2003年的大俯冲势力地震，降落后的降落后，由这些地震触发，最近发现非沃尔底克震颤提供了一个极好的机会，可以严格确定这三个过程沿俯冲界面及其透露效果的效果以及效果的效果变化的效果，并确定这些三个过程的位置。来自MSZ的Michoacan，Guerrero和Oaxaca片段的GPS和地震数据将用于研究两个区域中两个区域中的情节短暂滑移是如何以及是否在时空连接的，并且该滑移相对于地震源性区域和两个区域的非volcanic震颤发生。将使用相同的数据来确定沿这些沟槽段的经过震荡耦合的分布以及地震危险。来自Chiapas沟渠段的GPS数据将用于测试此处的瞬态滑移，并估算了跨界锁定的程度，以更好地理解Chiapas地震间隙的原因。与危险相关的有用输出将包括大多数易于地震的MSZ沿大多数地震锁定率的估计，评估墨西哥南部的瞬态滑移是在墨西哥载荷中的瞬态滑移还是卸载地震生成区的较低面积以及对墨西哥最活跃的火山的Volcan Fuego de Colima上及其周围的变形速率的持续监测。 UNAVCO的一个子奖项将使Demets和Hismexican合作者建立的35个连续的GPS电台的持续运作和维护，这构成了墨西哥的三分之一GPS基础设施。最后，该项目将资助2名UW研究生。项目参与者将向学生，教职员工和墨西哥政府官员进行外展活动。