Study of the structure and seismicity of the February 27, 2010 Chile Mw 8.8 earthquake rupture zone

小组提案的主要目的在摘要文件中作了说明。该项目的主要目标是利用2010年2月27日开始的8.8级Maule地震，智利南部边缘的地震序列，进一步了解大地震、辐合边缘结构和震后松弛过程之间的关系。这个序列提供了一个前所未有的机会，可以非常详细地描绘余震活动和大地震破裂带的结构，并确定该地区的精确速度模型。在主震发生后不久，各个国际小组沿着整个500公里长的断裂带安装了一个由142个地震仪站组成的密集网络。在该项目的第一阶段，将使用绝对和相对震源定位技术探测和定位余震。余震的时空特性反映了地震后的松弛过程和其中的结构。余震将有助于澄清在大地震的震后阶段应力是如何释放的，并将解析俯冲带浅层部分的结构。局部地震层析成像将用于确定速度模型。为了处理正在进行的余震系列的大量地震记录数据，将应用、测试和改进以前的（半）自动化技术。Pichilemu市周围明显且持续的地壳地震活动群，包括6.9级的正常断层余震，将是重点区域之一。目的是阐明在汇聚俯冲带背景下这些伸展事件的原因。建议与其他俯冲带背景进行比较，以更好地了解2010年Maule大地震序列的区域地震构造情况。

The principle aims of the group proposal are described in the summary document. The main objective of the proposed project is to further our understanding of the relationships between great earthquakes, the structure of convergent margins and postseismic relaxation processes using the earthquake sequence along the Southern Chilean margin which started on 27 February 2010 with the Mw 8.8 Maule earthquake. This sequence provides an unprecedented opportunity to image the aftershock activity in great detail and structure of the rupture zone of a great earthquake, and to determine an accurate velocity model for the region. A dense network of 142 seismograph stations was installed by various international teams shortly after the mainshock along the entire 500 km long rupture zone. In the first stage of the project, aftershocks will be detected and located using absolute and relative hypocentre location techniques. The spatial-temporal behaviour of the aftershocks reflects postseismic relaxation processes and the structure therein. The aftershocks will help to clarify how stress is released in the postseismic phase of a great earthquake, and will resolve structures within the shallow part of the subduction zone. Local earthquake tomography will be applied to determine the velocity model. In order to process the large amount of seismogram data of the ongoing aftershock series previous (semi-)automated techniques will be applied, tested and improved. A pronounced and ongoing cluster of crustal seismicity around the city of Pichilemu, including a normal faulting aftershock of magnitude Mw 6.9 will be one of the focus areas. The aim will be to eludicate the reason for these extensional events in the convergent subduction zone setting. A comparison with other subduction zone settings is suggested to better understand the regional seismotectonic situation of the great 2010 Maule earthquake sequence.