NSF/EAR-BSF:Aftershock Productivity in Context of Rupture Kinematics

在当前数据丰富的时代，余震研究蓬勃发展。在经验上预测地震后会产生多少余震方面已经取得了实质性的进展。虽然预测余震的时间和规模在历史上受到了更多的关注，但预计的余震总数也是一个可靠的观测结果。 一般来说，7级地震产生的余震是6级地震的10倍，而且这种模式在所有震级下都是持续的，即，余震的数量每增加一个震级单位就增加10倍。这个项目要问的是，为什么余震的产生会遵循这种模式？它包含了哪些关于地震力学的信息？为什么有些地震（例如2017年恰帕斯地震）会产生很多余震，而另一些地震（例如2017年墨西哥城地震）只产生很少的余震？ 最重要的是，这些信息是否可以用来预测灾难发生后关键几天的余震产生？该项目对我们理解地震危害具有更广泛的意义，并增加了美国和以色列的科学伙伴关系。这项工作还将支持研究生和一名本科生研究人员进行研究，作为项目的一部分。利用统计地震学的工具，在这些问题上已经花费了大量的努力。许多研究都集中在统计数据最可靠的区域地震上。分离出余震产生的原因，可以从单个主震的滑动模式的信息中受益，这些信息可以使用全球地震数据得出。以前的研究试图通过将余震数据与滑动的时间和分布信息相结合来解决这个问题。这些研究很有见地，但一般缺乏统计分析所需的主震数量。这种缺乏的部分原因是，直到最近，滑动图仍然非常困难，只能用于少数情况。因此，很难对余震和主震破裂之间的关系提出问题，因为不同的模型有不同的偏见。这种情况已经发生了巨大的变化，最近出版的大型汇编的破裂序列一致地用一种方法。这项工作开创了一个将运动断裂及其随后的余震信息结合起来的新时代。研究人员将利用这种能力，通过以下方式攻击余震生产力：（1）利用余震的空间分布相对于分辨率良好的同震滑动图来阐明震级依赖性的物理起源，（2）调查生产力的区域变化，（3）检查余震生产力，区域强度，该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

Aftershock studies have blossomed in the current data-rich era. Substantial progress has been made in empirically predicting how many aftershocks are produced in the aftermath of an earthquake. Although predicting the timing and size of aftershocks have received more attention historically, the expected total number of aftershocks is just as robust an observation. In general, a magnitude 7 earthquake produces 10 times as many aftershocks as a magnitude 6 and the pattern continues for all magnitudes, i.e., the number of aftershocks increases by a factor of 10 for each magnitude unit. The project asks why does aftershock production follow this pattern? What information does it contain about earthquake mechanics? Why do some earthquakes, like the 2017 Chiapas earthquake produce many aftershocks, while others, like the 2017 Mexico City earthquake produce only a few? And most importantly, can this information be used to anticipate the aftershock production in the critical days following a disaster? This project has broader implications for our understanding of earthquake hazards, and adds to the US-Israel scientific partnership. The work will also support graduate students and an undergraduate researcher to conduct research as part of the project. Significant effort has been spent on these questions utilizing tools from statistical seismology. Many studies have focused on regional earthquakes, where statistics are most robust. Separating out the causes of aftershock production can benefit from information of the slip patterns of individual mainshocks that can be derived using global seismic data. Previous studies have strived to attack this problem by combining aftershock data with information about the timing and distribution of slip. The studies have been insightful, but have generally lacked the number of mainshocks required for statistical analysis. This lack has been, in part, because until recently slip maps were sufficiently difficult that they were only available for a small number of cases. Therefore, it was difficult to ask questions about the relation between aftershocks and mainshock rupture since different models are biased in different ways. This situation has changed dramatically with recently published large compilations of rupture sequences done uniformly with a single method. This work exploits a new era of combining information from kinematic ruptures and their ensuing aftershocks. The researchers will capitalize on this capability and attack aftershock productivity by: (1) using the spatial distribution of aftershocks relative to well-resolved coseismic slip maps to clarify physical origins of the magnitude dependence, (2) investigating regional variations in productivity, and (3) examining the interrelationship between aftershock productivity, regional strength, and arrest criteria for mainshock rupturesThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.