Collaborative Research: Deep megathrust conditions by comparing seismicity rates and source parameters with tremor, slow slip, and the Mw 7.4 Ometepec, Mexico earthquake

合作研究：通过比较地震活动率和震源参数与地震、慢滑移和墨西哥 Mw 7.4 奥梅特佩克地震来了解深部巨型逆冲条件

• 批准号: 1246944
• 负责人: Michael Brudzinski
• 金额: $ 16.1万
• 依托单位: Miami University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246944&HistoricalAwards=false
• 关键词: Collaborative; Research; Deep; megathrust; conditions

Recent discoveries that demonstrate the wide spectrum of fault slip along subduction megathrust faults prompt important questions about the relationships between large earthquakes, small earthquakes, slow slip, and non-volcanic tremor. In many areas, the deep portion of the fault that lies at the transition between the fast and slower slip mechanisms is out of view, sitting offshore, away from nearby monitoring. However, an existing seismic and geodetic network along the Oaxacan segment of the Middle America subduction zone provides an excellent dataset for use to quantify earthquake occurrence and source parameters in an area that has experienced M 7 earthquakes, tremor, and slow slip events. This research will address several hypotheses related to the spatial and temporal relationships between slow slip, tremor, and large earthquakes. These include determining 1) if a sharp transition in seismicity characteristics exists along the megathrust as events approach the downdip seismicity limit and the area of episodic tremor and slip, 2) if slow slip events produce stress loading in adjacent regions that lead to increased seismicity rates and changes in source characteristics of small earthquakes, and 3) if large earthquakes are associated with temporal changes in earthquake occurrence and source characteristics in adjacent regions due to stress changes. We will employ several seismological techniques, including the construction of a uniform event catalog, focal mechanism determination, rupture duration and stress drop calculations, and investigation of seismicity rates along specific fault patches, to address these hypotheses.The overall goals of the project revolve around a better understanding of the deep roots of the earthquake-producing region of the Mexican subduction zone, with applicability to other global subduction zones. Thus the results of the study will produce societal benefits related to earthquake hazards, particularly in providing information needed for improving temporal variations in probabilistic seismic hazard. The outcome of this project will include data products disseminated to a wide international community through meeting presentations, publications, and archival in the relevant data repositories. The project will train 4 US based graduate and undergraduate students as well as provide capacity-building seismological training for 2 Mexican students. Another outcome of the project will be 2 educational lessons that will be disseminated through online educational activity portals.

最近的发现表明，沿着俯冲巨型逆冲断层的断层滑动范围很广，这引发了关于大地震、小地震、慢滑和非火山震动之间的关系的重要问题。在许多地区，位于快速滑动机制和较慢滑动机制之间转换点的断层的深部是看不到的，位于近海，远离附近的监测。然而，沿中美俯冲带瓦哈坎段的现有地震和大地测量网络提供了一个极好的数据集，用于量化经历过7级地震、震动和慢滑事件的地区的地震发生和震源参数。这项研究将解决与慢滑、震动和大地震之间的时空关系相关的几个假说。这包括：1)当地震活动接近下倾地震活动极限和幕式震动滑移区时，是否沿大断裂存在地震活动特征的急剧转变；2)慢滑事件是否在邻近地区产生应力载荷，从而导致地震活动速率增加和小震震源特征的变化；3)大地震是否与由于应力变化而导致的地震发生和邻近地区震源特征的时间变化有关。我们将使用几种地震学技术，包括建立统一的事件目录，确定震源机制，计算破裂持续时间和应力降，以及调查特定断裂带的地震活动率，以解决这些假设。该项目的总体目标是更好地了解墨西哥俯冲带地震孕育区的深层根源，并适用于其他全球俯冲带。因此，研究结果将产生与地震灾害有关的社会效益，特别是在提供改善概率地震危险的时间变化所需的信息方面。该项目的成果将包括通过会议介绍、出版物和相关数据储存库的档案向广泛的国际社会传播数据产品。该项目将培训4名美国研究生和本科生，并为2名墨西哥学生提供能力建设地震学培训。该项目的另一个成果是将通过在线教育活动门户网站传播2节教育课。