德国卡尔斯鲁厄理工学院Rietbrock, Andreas的课题组取得一项新突破。他们的最新研究揭示了俯冲界面多断层网的地震证据。2024年4月17日出版的《自然》杂志发表了这项成果。

研究人员对这些具有地震活动的米级断层进行了探测，并展示了它们对余震传播的影响。本研究利用当地三维速度模型和对厄瓜多尔1,500多次双差重新定位地震的密集观测，获得了非常详细的地震活动性图像。结果表明，地震有时发生在单一平面上，有时发生在板块界面带内几米厚同时活跃的亚平行平面上。

这种几何复杂性影响了余震传播，证明了断层连续性和构造对发震界面滑动的影响。研究结果强调，该发现可以帮助在俯冲带建立更真实的地震破裂、无震滑动和地震灾害的模型。

据悉，地球上最大的地震俯冲带处产生，但人们对俯冲带的详细结构及其对地震和无震滑动的影响仍然知之甚少。化石俯冲带的地质研究将地震成因界面描述为100m至1km厚的带，形变主要发生在米级断层上。相反，人们对地震学研究的空间覆盖范围和时间分辨率较大，空间分辨率较低，通常将发震界面成像为1km宽的地震活动带。然而，这些米级结构如何以及何时在地震周期时间尺度上活跃，以及它们对形变的影响是未知的。

附：英文原文

Title: Seismological evidence for a multifault network at the subduction interface

Author: Chalumeau, Caroline, Agurto-Detzel, Hans, Rietbrock, Andreas, Frietsch, Michael, Oncken, Onno, Segovia, Monica, Galve, Audrey

Issue&Volume: 2024-04-17

Abstract: Subduction zones generate the largest earthquakes on Earth, yet their detailed structure, and its influence on seismic and aseismic slip, remains poorly understood. Geological studies of fossil subduction zones characterize the seismogenic interface as a 100 m–1km thick zone in which deformation occurs mostly on metres-thick faults. Conversely, seismological studies, with their larger spatial coverage and temporal resolution but lower spatial resolution, often image the seismogenic interface as a kilometres-wide band of seismicity. Thus, how and when these metre-scale structures are active at the seismic-cycle timescale, and what influence they have on deformation is not known. Here we detect these metres-thick faults with seismicity and show their influence on afterslip propagation. Using a local three-dimensional velocity model and dense observations of more than 1,500 double-difference relocated earthquakes in Ecuador, we obtain an exceptionally detailed image of seismicity, showing that earthquakes occur sometimes on a single plane and sometimes on several metres-thick simultaneously active subparallel planes within the plate interface zone. This geometrical complexity affects afterslip propagation, demonstrating the influence of fault continuity and structure on slip at the seismogenic interface. Our findings can therefore help to create more realistic models of earthquake rupture, aseismic slip and earthquake hazard in subduction zones.

DOI: 10.1038/s41586-024-07245-y

Source: https://www.nature.com/articles/s41586-024-07245-y