Collaborative Research: Aftershock Imaging with Dense Arrays (AIDA) for the August 23, 2011, Mw 5.8, Virginia earthquake aftershock sequence

这一快速支持使用IRIS/PASSCAL提供的地球镜灵活阵列的仪器在震后部署新型高密度地震阵列，以调查2011年8月23日发生在弗吉尼亚州的5.8级地震。这次地震具有北东走向的反向断层震源机制，震源深度为6千米(USGS)，发生在以前被认为是弗吉尼亚中部地震带的地震区。这次地震经过了美国地质勘探局1981年收缩的约15公里的NW-SE向深地震反射剖面，为将地震活动与美国东部深部结构联系起来提供了难得的机会。震中初步估计表明，地震发生在一个复杂的东倾反射带内，该带定义了阿巴拉契亚山前中部的动植物古生代逆冲板块，位于约9公里深的格伦维尔基底之下。通过将地震定位技术与高分辨率构造成像技术相结合，这项实验旨在展示被动和主动地震技术如何利用余震来识别深部孕震构造，以及在这两种信息都很少或根本不存在的地区的能量传播特征。记录实验利用新一代记录技术，构成了以前所未有的分辨率成像地震过程和相关构造的原型。如果数据像预期的那样丰富，这项实验很可能会为未来的余震研究建立一个新的方案。

This RAPID supports post-seismic deployment of novel high density seismic arrays usinginstruments from the Earthscope Flexible Array provided by IRIS/PASSCAL to investigate theMw 5.8 Virginia earthquake of August 23, 2011. This event had a NE-striking reverse faulting focalmechanism, a hypocentral depth of 6 km (USGS), and occurred in a previously recognized seismicregion known as the ?Central Virginia Seismic Zone?. This event passes with ca. 15 km of a NW-SEoriented deep seismic reflection profile contracted in 1981 by the USGS, providing a rare opportunityto link seismicity to deep structure in the eastern U.S. The preliminary hypocentral estimate suggeststhat the earthquake occurred within a complex zone of east-dipping reflections that define animbricated Paleozoic thrust sheet of the central Appalachian Piedmont that is underlain by Grenvillebasement at a depth of ca. 9 km.By merging the technologies of earthquake location with high resolution structural imaging, this experiment seeks to demonstrate how aftershocks can be exploited by both passive and active seismic techniques to identify seismogenic structures at depth as well as energy propagation characteristics for a region where both types of information are either rare or non-existent. The recording experiment constitutes a prototype for imaging earthquake processes and associated structures with unprecedented resolution by exploiting a new generation recording technologies. If the data proves as rich as expected, this experiment may well establish a new protocol for future aftershocks studies.