RAPID: Collaborative Research: Seismic Response to the 2016 M5.8 Pawnee Earthquake

自2009年以来，美国中西部地区的诱发地震或由污水注入或二次采油等人类活动引起的地震活动一直在增加。俄克拉荷马州被称为“新的地震之都”，在过去的几年里，该州的M3级地震率超过了加利福尼亚州。2016年9月3日发生在俄克拉何马州波尼市的地震发生在诱发地震活动区内，靠近污水处理井，是该州有记录以来最大的地震。这场地震发生在第二大地震发生五年后，2011年11月7日布拉格发生类似规模的地震。在波尼附近，当地居民报告了强烈的地面震动，房屋受损，地面裂缝，以及对安全的担忧。康奈尔大学和哥伦比亚大学的学生与当地大学合作，包括俄克拉荷马大学、俄克拉荷马州立大学和塔尔萨大学，积极参与在震中地区周围快速部署25个地震台。相关机构的学生一直积极参与学习传感器、网络设计和地震物理。在Pawnee事件中破裂的主要断层是一个与已映射的Labette断层相交的未映射断层，该断层曾发生大量余震，包括最大余震(M3.9级)。快速(2天内)部署地震仪器以来在该地区记录到的余震序列和相关地震活动将有助于研究余震和区域断裂系统上可能触发的地震活动。在接下来的几周里，我们将再部署20个短期观测站，记录12个月的数据。这个组合网络将提供有关断层结构、余震衰减、持续时间以及与注入速率变化相互作用的信息。这些数据将有助于了解存在巨大破坏性地震的断层的特征，并将有助于评估俄克拉荷马州和中部大陆的地震危险性。这种快速部署的广泛影响将有助于了解俄克拉荷马州北部的区域构造格局，并可能阐明最近的地震活动与该地区流体注入活动之间的关系。

Induced earthquakes, or seismicity caused by human activity such as wastewater injection or secondary oil recovery, have been increasing in the midwestern United States since 2009. The state of Oklahoma has become known as "the new earthquake capital", with earthquake rates of M3 exceeding those of California in the last few years. The 3 September 2016 Mw5.8 Pawnee, Oklahoma earthquake occurred within the region of induced seismicity, near wastewater disposal wells, and was the largest earthquake ever recorded within the state. The earthquake occurred five years after the second largest earthquake, the similarly sized Mw5.7 November 2011 Prague earthquake. Near Pawnee, local residents reported strong ground-shaking, damage to houses, cracks on the ground, and concerns about safety. Students from Cornell University and Colombia University, in collaboration with local universities including the University of Oklahoma, Oklahoma State University, and University of Tulsa, actively participated in the rapid deployment of 25 seismic stations around the epicentral region. Students of the institutions involved have been actively involved in learning about sensors, network designs, and earthquake physics. The main fault the ruptured during the Pawnee event was an unmapped fault intersecting mapped Labette Fault, which has hosted a significant number of aftershocks include the largest aftershock (M3.9). The aftershock sequence and related seismic activity in the region that has been recorded since the rapid (within 2 days) deployment of seismic instrumentation will help study aftershocks and the likely triggered seismicity on the regional fault systems. In the coming weeks, we will deploy an additional 20 short-period stations that will record data for 12 months. This combined network will provide information on fault structure, aftershock decay, duration, and interaction with injection rate variations. The data will help to understand the characteristics of faults that host large damaging earthquakes, and will help to assess earthquake hazards in Oklahoma and the midcontinent. The broader impact of this rapid deployment will help understand the regional tectonic framework in northern Oklahoma and may elucidate the relationship between this recent seismic activity with the fluid injection activities in the region.