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

最近的发现表明，广泛的断层滑动沿着俯冲巨型逆冲断层提示大地震，小地震，慢滑，和非火山震颤之间的关系的重要问题。 在许多地区，位于快速滑动机制和慢速滑动机制之间的过渡处的断层深部位于海上，远离附近的监测。 然而，现有的地震和大地测量网络沿着中美洲俯冲带的瓦哈坎段提供了一个很好的数据集，用于量化地震发生和源参数在一个地区，经历了7级地震，震颤，和缓慢滑动事件。 这项研究将解决几个假设有关的空间和时间之间的关系，慢滑，震颤，大地震。这些包括确定1）当事件接近下倾地震活动性极限和幕式震颤和滑动区域时，地震活动性特征是否存在沿着大逆冲断层的急剧转变，2）缓慢滑动事件是否在相邻区域产生应力负荷，导致地震活动率增加和小地震震源特征的变化，大震是否与应力变化引起的邻近地区发震和震源特征的时间变化有关。我们将采用几种地震学技术，包括建立统一的事件目录，确定震源机制，破裂持续时间和应力降计算，以及调查沿着特定断层片的地震活动率，以解决这些假设。该项目的总体目标围绕着更好地了解墨西哥俯冲带地震发生区的深层根源，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灾害的时间变化所需的信息。该项目的成果将包括通过会议演示、出版物和相关数据存储库中的档案向广大国际社会传播的数据产品。 该项目将培训4名美国研究生和本科生，并为2名墨西哥学生提供地震学能力建设培训。 该项目的另一项成果是将通过在线教育活动门户网站传播2节教育课。

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.