Collaborative research: A study of transient aseismic slip and non-volcanic tremor in southern Mexico with large aperture seismic and GPS arrays

合作研究：利用大孔径地震和GPS阵列研究墨西哥南部瞬态地震滑移和非火山地震

• 批准号: 0510887
• 负责人: Dennis DeMets
• 金额: $ 16.57万
• 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: 2005
• 资助国家: 美国
• 起止时间: 2005-09-15 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0510887&HistoricalAwards=false
• 关键词: Collaborative; research; study; transient; aseismic

Intellectural merit: Funds are requested for a joint geodetic and seismic study ofthe Oaxaca-Guerrero segment of the Middle America subduction zone, one of the few placeson earth where land-based GPS and seismic observations can be used to study both thelocked, seismogenic area of a subduction interface and region of deeper transitionalslip, where episodic tremor and slip may originate. The principal scientific goal isto better understand the recently discovered phenomenon of episodic slip transientsand its role in either relieving or increasing strain accumulating along the seismogenicportion of a subduction interface. A pilot study during the past year shows that suchtransients are occurring as frequently as every 12-24 months in this region, thatsome transients (1998 and 2004) originate far outside the Guerrero seismic gap, andthat the transients may be accompanied by non-volcanic seismic tremors. Based on thesepreviously unrecognized results, deployment for 24 months of an 8-station broadbandseismic array and expansion of a regional continuous GPS array to include 4 criticallylocated stations in a region where the transients appear to occur are planned. Thenew seismic array, which will span abroad gap between two dense seismic transects being installed as part of the alreadyfunded Caltech/UNAM Middle America Seismic Experiment, will allow detection and locationof any episodic tremors in the study area. Continuous GPS measurements from thepre-existing GPS stations and nine new stations constructed by this group andcollaborator Enrique Cabral of UNAM will provide critical complementary informationabout the source regions, magnitude, and timing of episodic slip. Data from an existingsmaller-footprint 30-station continuous and campaign GPS array that DeMets and Cabraloperate in Oaxaca above the Cocos-North America subduction interface will also be usedto study in more detail deformation within a conspicuous seismic gap analogous to,but smaller than the well-known Guerrero seismic gap. The combined GPS and seismicarrays will be a powerful tool for studying subduction transients and non-volcanictremor, and for imaging spatial and temporal variations in frictional couplingalong the locked and transitional zones beneath our network. Brudzinski, who will bea new faculty member at Miami University of Ohio in August of 2005, will purchase thenecessary seismic equipment with start-up funds from his faculty position and willhave it prepared for a two-year deployment in early 2006. DeMets at UW-Madison willcoordinate the GPS station installation with Dr. Cabral, as well as a modest expansionof the Oaxaca GPS network to improve coverage of the aforementioned seismic gap. TheUW-Madison geophysics group has a long history of deploying seismic and GPS networksand will provide at no cost two expert technicians to help build and maintain thecombined seismic and GPS network. Responsibilities for modeling of the geodetic andseismic observations will lie respectively with DeMets and Brudzinski.Broader impacts: Episodic tremor and slip are a newly observed phenomenon that appearsto be related to many different aspects of earth science (seismology, tectonics,petrology, and geodynamics), with possible ramifications for understanding triggeringof megathrust earthquakes. Students at Miami University will be offered a unique opportunityto participate in a field workshop course that will coincide with the initial seismicdeployment, thereby exposing students to a geophysics field research. Broader impacts atUW-Madison will include education of Mexican graduate student Francisco Correa-Mora,who will do a substantial portion of his dissertation research on the mechanics ofsubduction along the Middle America trench. The availability of new continuous andcampaign GPS and seismic data to the broader geophysical community will alsoextend the impact of this work beyond our group, particularly once future transientslip episodes and/or tremor sequences are recorded.

Intellectural merit: Funds are requested for a joint geodetic and seismic study ofthe Oaxaca-Guerrero segment of the Middle America subduction zone, one of the few placeson earth where land-based GPS and seismic observations can be used to study both thelocked, seismogenic area of​​ a subduction interface and region of deeper transitionalslip, where episodic tremor and slip may originate.主要的科学目标是更好地了解最近发现的情节滑移瞬变现象及其在缓解或增加沿俯冲界面的地震生成型菌株中积累的作用。在过去的一年中，一项试点研究表明，这种传输发生频率与该地区每12-24个月一样频繁地发生，Thandome Transiations（1998和2004）远远超出了Guerrero地震间隙，而瞬态可能伴随着非volcanic的地震震颤。 基于该epthe的结果，在8个建筑宽带阵列的24个月内部署以及区域连续GPS阵列的扩展，包括在似乎发生瞬变的区域中包括4个批判性的站点。当时的地震阵列将跨越在两个已筹集的CALTECH/UNAM中美洲地震实验的两种密集地震样带之间的国外差距，将允许检测和研究区域的任何情节震颤的位置。来自UNAM的该组和Collaborator Enrique Cabral构建的九个新电台的连续GPS测量将提供临界互补的信息，以示源区域，源区域，幅度和情节滑移时间。来自Cocos-North America俯冲界面上方的OXACA中的OXET和Cabraloperate的AbotingsMaller-footprint 30站连续和活动的GPS阵列的数据也将用于更详细地研究明显的地震间隙内的变形，但类似于与众所周知的Guerrero Seismic Seismic Seismic Gap相似，但要小。联合GP和地震阵列将是研究俯冲瞬变和非volcanictremor的强大工具，以及在我们网络下方锁定的锁定和过渡区域中对摩擦耦合的空间和时间变化进行成像。布鲁津斯基（Brudzinski）将于2005年8月将在俄亥俄州迈阿密大学的新任教职员工中获得新的教职员工，他将通过其教职员工的启动资金购买当时的不必要的地震设备，并将为2006年初的两年部署做好准备。地震差距。 Theuw-Madison Geophysics小组在部署地震和GPS网络方面拥有悠久的历史，将无需提供两名专家技术人员，以帮助建立和维护结合稳定的地震和GPS网络。对大地测量和理想观察进行建模的责任将分别依赖于Demets和Brudzinski.Boader的影响：情节震颤和滑倒是一种新观察到的现象，与地球科学的许多不同方面有关（地震学，构造学，构造，岩石学和地球动物学）以及可能的地球构成了RAMIFICTICS，它与地球科学的许多不同方面有关。迈阿密大学的学生将获得一个独特的机会，可以参加野外研讨会课程，该课程将与最初的地震剥离相吻合，从而使学生接受地球物理野外研究。 ATUW-MADISON的更广泛影响将包括对墨西哥研究生Francisco Correa-Mora的教育，他将对中美洲沟渠的机制进行论文研究的很大一部分。新的连续GP和地震数据对更广泛的地球物理群落的可用性也将使这项工作的影响超出我们的小组之外，尤其是一旦记录了未来的TransiNtsLIPT情节和/或震颤序列。