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The Fine Structure of a Seismogenic Zone Revealed by Aftershocks of the 2014 Iquique Mw 8.1 Earthquake

2014 年伊基克 8.1 级地震余震揭示的发震带精细结构

基本信息

批准号：
399171538
负责人：
Dr. Dietrich Lange
金额：
--
依托单位：
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/399171538?language=en
关键词：
Fine Structure Seismogenic Zone Revealed

项目摘要

The majority of global earthquakes occur along subduction zones. During great earthquakes (M>8) along these convergent plate boundaries the interface between the plates ruptures down to depths of ~40 km. The trench marks the onset of subduction and the seismogenic zone where large ruptures occur is almost exclusively located beneath the marine forearc. The objective of the proposed project is to nurture our understanding of the structural influence on postseismic relaxation processes of a marine forearc using high-resolution location techniques of an aftershock sequence. Here, we want to focus on the erosive margin in North Chile where the Mw 8.1 Iquique earthquake on 1 April 2014 ruptured the marine forearc. We propose to combine 24 months of continuous data from 14 ocean bottom stations (OBS) installed between December 2014 and November 2016 with the data from the permanent IPOC network and temporary landstations. The integration of the offshore OBS data with the onshore seismology data provides a shore-line crossing data set with the exceptional capability to fully image the Northern Chilean forearc in its entity. Previous data sets were only capable to capture the offshore domain up to the continental shelf or the onshore portion from the arc to the coastline. Here, we have the unique opportunity to bridge this gap. In particular, we want to investigate seismicity in the 2014 rupture area and the transition to the remaining seismic gap to the south of the Iquique earthquake, which last ruptured in 1877. In the first phase of the project we plan to detect and locate the seismicity in order to obtain a high-resolution earthquake catalogue. This will allow resolving the spatial relation between postseismic activity and structural features such as variations in the topography of the plate interface, splay faults, internal structure of the seismogenic zone or transient fluid migration into the overriding plate, to establish a possible correlation between dehydration processes and the seismicity distribution in the upper plate. Then, local earthquake tomography will be applied to determine the 2D and 3D vp and vp/vs velocity structure and will contribute to a better understanding of lateral and downdip structural changes of the forearc. The findings will be jointly interpreted with the results of a recent high-resolution reflection seismic grid and a 3D refraction experiment dataset acquired during 2016 with RV Langseth. The project proposed here hence targets a unique holistic approach by combining shore-line crossing seismology data with information from 2D and 3D active seismic experiments and structural constraints on tectonic segmentation data.

全球大部分地震都发生在沿着俯冲带。在沿着这些会聚的板块边界的大地震（M>8）期间，板块之间的界面破裂到~40 km的深度。海沟标志着俯冲的开始，而发生大破裂的孕震区几乎完全位于海洋前弧之下。拟议项目的目标是培养我们的理解结构的影响，地震后的松弛过程的海洋前弧使用高分辨率定位技术的余震序列。在这里，我们想把重点放在智利北部的侵蚀边缘，2014年4月1日伊基克8.1级地震破坏了海洋前弧。我们建议将2014年12月至2016年11月期间安装的14个海底站（OBS）的24个月连续数据与永久IPOC网络和临时陆地站的数据相结合。海上OBS数据与陆上地震学数据的集成提供了一个具有特殊能力的海岸线穿越数据集，可以在其实体中对智利北方前弧进行全面成像。以前的数据集只能捕捉到从岛弧到海岸线的近海区域到大陆架或陆上部分。在这方面，我们有独特的机会弥合这一差距。特别是，我们想调查2014年破裂区域的地震活动，以及向伊基克地震南部剩余地震空区的过渡，伊基克地震最后一次破裂是在1877年。在该项目的第一阶段，我们计划探测和定位地震活动，以获得高分辨率的地震目录。这将有助于解决地震后活动和结构特征之间的空间关系，如板块界面的地形变化，展布断层，孕震区的内部结构或瞬态流体迁移到覆盖板块，以建立脱水过程和地震活动分布之间的可能相关性在上板块。然后，当地的地震层析成像将被应用于确定的二维和三维的vp和vp/vs速度结构，并将有助于更好地了解横向和下倾结构的变化的前弧。这些发现将与最近的高分辨率反射地震网格和2016年与RV Langseth获得的3D折射实验数据集的结果进行联合解释。因此，这里提出的项目的目标是一个独特的整体方法相结合的海岸线穿越地震数据与信息从二维和三维主动地震实验和构造分割数据的结构约束。