Anatomy of a Subduction Zone from Ocean Mantle to Crust: Seismicity and Seismic Structure in Northern Chile

从洋幔到地壳的俯冲带解剖：智利北部的地震活动和地震结构

• 批准号: 275837588
• 负责人: Dr. Jörn Kummerow
• 金额: --
• 依托单位: Fachrichtung Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/275837588?language=en
• 关键词: Anatomy; Subduction; Zone; Ocean; Mantle

The principal aim of this project is the investigation of subduction-related seismic structures, including the fine-scale structure of the megathrust shear zone and underlying oceanic plate, and of earthquake sources in the northern Chile forearc employing a suite of innovative methods of seismicity processing, imaging and interpretation. We will exploit the specific situation, where an extraordinarily high rate of seismicity has been recorded for almost ten years on a large number of seismic stations, including the permanent IPOC network and several temporary networks. Northern Chile, in particular the recently installed MEJIPE network on the Mejillones peninsula, also offers a rare chance to monitor at least a part of the seismogenic zone onshore. We therefore expect to image the structural and seismic architecture of this subduction zone at highest possible resolution.In order to image seismic structures in detail, we will apply a recently developed micro seismic migration-based approach, complemented by the modelling of near-source reflections and conversions and the estimation of local variations of the Poisson ratio from precise differential arrival times. We will also characterize the earthquake sources themselves using moment tensor inversion in the time domain and the analysis of seismogram spectra to derive other source parameters like stress drop and radiation efficiency.The synthesis of the results will allow to test, if the major seismic signatures in the subduction system are fluid controlled. Processes such as dewatering of hydrated minerals, trapping and pressurization of fluids and fluid migration should leave a strong imprint on the elastic parameters and the spatio-temporal characteristics of seismicity. This imprint will be detectable by our study, e.g. as zones of ultra low velocity and/or anomalous high local Vp/Vs ratios.An important component of the project will be the detailed study of seismicity and related physical processes in the deepest, upper ocean mantle layer of the newly confirmed shallow triple seismic zone in northern Chile. Eventually this will contribute to advance the understanding of intermediate depth earthquakes in general.

该项目的主要目的是调查与俯冲有关的地震结构，包括巨型逆冲断层剪切带和下伏海洋板块的精细结构，以及智利北方前弧的震源，采用一套创新的地震活动处理、成像和解释方法。我们将探讨这一特殊情况，即近十年来，大量地震台站记录到异常高的地震活动率，包括永久性IPOC网络和几个临时网络。智利北方，特别是最近在Mejillones半岛上安装的MEJIPE网络，也提供了一个难得的机会，至少可以监测一部分陆上的地震孕育区。因此，我们期望以尽可能高的分辨率成像该俯冲带的结构和地震结构。为了详细成像地震结构，我们将应用最近开发的基于微地震偏移的方法，辅之以近源反射和转换的建模以及根据精确的差分到达时间估计泊松比的局部变化。我们还将使用时间域中的矩张量反演和地震图频谱分析来表征地震源本身，以获得其他源参数，如应力降和辐射效率。结果的合成将允许测试，如果俯冲系统中的主要地震特征是流体控制的。水化矿物的脱水、流体的捕获和加压以及流体迁移等过程应在弹性参数和地震活动的时空特征上留下深刻的印记。我们的研究可以探测到这种痕迹，例如超低速区和/或局部Vp/Vs比值异常高的区域，该项目的一个重要组成部分将是详细研究智利北方新确认的浅层三重地震带的最深海洋上地幔层的地震活动和有关物理过程。最终，这将有助于提高对中等深度地震的认识。

项目成果

Filling the gap in a double seismic zone: Intraslab seismicity in Northern Chile

填补双地震带的空白：智利北部的板内地震活动

• DOI: 10.1016/j.lithos.2019.105155
• 发表时间: 2019
• 期刊: Lithos
• 影响因子: 3.5
• 作者: C. Sippl;B. Schurr;T. John;S. Hainzl
• 通讯作者: S. Hainzl

Seismicity Structure of the Northern Chile Forearc From >100,000 Double‐Difference Relocated Hypocenters

超过 100,000 个双差重定位震源的智利北部弧前地震活动结构

• DOI: 10.1002/2017jb015384
• 发表时间: 2018
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: C. Sippl;B. Schurr;G. Asch;J. Kummerow
• 通讯作者: J. Kummerow

Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone

• DOI: 10.1029/2019jb017764
• 发表时间: 2019-08-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
• 影响因子: 3.9
• 作者: Hainzl, S.;Sippl, C.;Schurr, B.
• 通讯作者: Schurr, B.

From Slab Coupling to Slab Pull: Stress Segmentation in the Subducting Nazca Plate

• DOI: 10.1029/2018gl078793
• 发表时间: 2018-06-16
• 期刊: GEOPHYSICAL RESEARCH LETTERS
• 影响因子: 5.2
• 作者: Bloch, Wasja;Schurr, Bernd;Shapiro, Serge A.
• 通讯作者: Shapiro, Serge A.

Probing the Northern Chile Megathrust With Seismicity: The 2014 M8.1 Iquique Earthquake Sequence

• DOI: 10.1029/2019jb017794
• 发表时间: 2019-12
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Hugo Soto;C. Sippl;B. Schurr;Juliane Kummerow;G. Asch;F. Tilmann;D. Comte;S. Ruiz;O. Oncken