Constraining Early-stage Rifting Through Rapid Response to the Lake Malawi Earthquake Sequence of December 2009

通过对 2009 年 12 月马拉维湖地震序列的快速反应来限制早期裂谷

• 批准号: 1019379
• 负责人: James Gaherty
• 金额: $ 1.3万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1019379&HistoricalAwards=false
• 关键词: Constraining; Early; stage; Rifting; Through

This RAPID proposal addresses nine earthquakes of magnitude 5 and larger that have taken place in the northern Malawi segment of the East African Rift (EAR) system. These events are extremely rare, and their swarm-like characteristics are highly unusual for this particular region and for the Western Branch of the EAR as a whole. They will deploy a network of 10 seismic stations in the region of these earthquakes to record further main shocks (if they occur) and aftershocks and to relocate these events to better constrain the fault(s) or other subsurface features that are causing them. In particular they will evaluate: (1) whether current events indicate that extension is being accommodated on the major basin-bounding border fault, or whether the extensional strain is occurring primarily on secondary faults in the hanging wall of the major system; and (2) whether deep magmatic activity is associated with the events. These earthquakes offer a rare and important opportunity to address key aspects of deformation and seismogenesis in an early stage rift. Accurate aftershock locations require observations from the epicentral region, where there is currently only one operating seismometer. A rapid deployment is necessary.The December 2009 earthquake sequence has resulted in threecasualties, hundreds of injuries and thousands of displaced people. Aftershocksassociated with the sequence continue, and given the swarm-like character of the dozen or so largest events, it is possible that additional damaging events are still to come. Malawi currently has very limited capacity to monitor and locate these earthquakes; they have no permanent national network, and as of this writing only two seismic stations are in northern Malawi region recording these events.The PIs will work closely with the Geological Survey of Malawi (GSM) in earthquake detection and location techniques, as well as with the USGS, USAID, and the US Embassy to coordinate with the other outreach and humanitarian efforts underway.

这一快速提案涉及东非裂谷系统马拉维北部发生的9次5级以上地震。这些事件极其罕见，它们的群状特征在这一特定区域和整个耳朵的西部分支都是非常罕见的。他们将在这些地震发生的地区部署一个由10个地震台组成的网络，以记录进一步的主震(如果发生)和余震，并重新定位这些地震，以更好地约束引起这些地震的断层(S)或其他地下特征。特别是，他们将评估：(1)当前事件是否表明主要的盆地边界断层上存在伸展作用，或者伸展应变是否主要发生在主要系统上盘的次级断层上；以及(2)深部岩浆活动是否与这些事件有关。这些地震提供了一个难得的重要机会来解决早期裂谷中的变形和地震成因的关键问题。准确的余震位置需要震中地区的观测，那里目前只有一个运行中的地震仪。必须迅速部署。2009年12月的一系列地震已造成3人死亡，数百人受伤，数千人流离失所。在与这一序列相关的震荡持续之后，考虑到十几个左右最大的事件的群状特征，可能还会有更多的破坏性事件到来。马拉维目前监测和定位这些地震的能力非常有限；他们没有永久的国家网络，截至撰写本文时，马拉维北部地区只有两个地震台记录这些地震。私人投资者将与马拉维地质调查局(GSM)在地震探测和定位技术方面以及与美国地质调查局、美国国际开发署和美国大使馆密切合作，以协调正在进行的其他外联和人道主义工作。