Slip budgeT in subduction zones illuminated by geodetic measuRements and earthquake cycle defOrmation modelliNG – STRONG project

板块边界的累积应变(滑动预算)决定了俯冲带大地震的位置和强度，通常会引发破坏性海啸。因此，对预算差额的调查和量化对于改进地震和海啸危险评估是最重要的。在过去几年中，丰富的地球物理和大地测量观测，以及在正演和反演模拟方面所做的巨大努力，使我们能够更好地调查滑动预算。尽管如此，地震后滑动以及非线性粘弹性和孔弹性松弛过程对观测到的地表变形、余震的发生和滑动预算的估计有多大程度的贡献仍然是一个悬而未决的问题。该项目旨在利用综合工作流程破译智利北部俯冲带的这些研究问题：1)不同时空尺度的卫星大地测量和地震活动数据，2.最先进的4D(空间和时间)地质力学正演模型，以及3.一种反转方法。智利北部为研究与地震旋回有关的形变过程提供了独特的机会，因为智利综合板块边界(IPOC)的多参数仪器成功地记录了2014年MW8.1Iquique地震之前、期间和之后的形变和地震活动。此外，智利北部相对较高的干旱程度导致了高干涉相干性，这是以前所未有的分辨率反演干涉合成孔径雷达(InSAR)数据的理想之选。具体地说，该项目将侧重于处理和分析2014年伊基克地震后的新InSAR数据。这些InSAR数据将大大提高全球导航卫星系统(GNSS)数据的空间密度，从而能够更好地约束考虑摩擦断层滑动、非线性粘性松弛和孔洞弹性过程的模型结果。有了这一量化信息和综合工作流程，本提案的目标是1。量化和了解在地震旋回中控制形变的过程的相对贡献，如地震间锁定、震后滑动(余滑)、非线性粘弹性和孔弹性松弛。2.)估计当前滑动预算的空间分布，这对于计算未来地震的震级和位置至关重要。3.)说明抗震和抗震滑移在总预算中的比例。4.)阐明孔隙压力变化在空间和时间上对余震的作用，特别是发生在地壳上的余震。

The accumulated strain at plate boundaries (slip budget) governs the location and magnitude of large earthquakes at subduction zones, often triggering destructive tsunamis. Hence, the investigation and quantification of slip budgets are of upmost importance to improve seismic and tsunami hazard assessment. During the last years, the wealth of geophysical and geodetic observations, as well as great effort in forward and inverse modelling have allowed a better investigation of slip budgets. Despite this, it is still an open question to what extent postseismic slip as well as non-linear viscoelastic and poroelastic relaxation processes contribute to the observed surface deformation, the occurrence of aftershocks, and the slip budget estimation. This project aims at deciphering these research questions in the northern Chile subduction zone using a comprehensive workflow that integrates: 1.) Satellite geodetic and seismicity data at variable spatiotemporal scales, 2.) a state-of-the-art 4D (space and time) geomechanical forward model, and 3.) an inversion approach. Northern Chile provides a unique opportunity to investigate earthquake cycle-related deformation processes as the deformation and seismicity before, during, and after the 2014 Mw 8.1 Iquique earthquake has been successfully recorded by the multi-parameter instrumentation of the Integrated Plate Boundary Chile (IPOC). Moreover, the relatively high aridity of northern Chile results in high interferometric coherence, ideal for retrieving Interferometric Synthetic-Aperture Radar (InSAR) data with an unprecedented resolution. Specifically, this project will focus on processing and analyzing new InSAR data following the 2014 Iquique earthquake. These InSAR data will substantially improve the spatial density of Global Navigation Satellite System (GNSS) data and thus will allow constraining the model results better considering frictional fault slip, non-linear viscous relaxation, and poroelastic processes. With this quantitative information and integrated workflow, this proposal aims at 1.) Quantifying and understanding the relative contribution of the processes controlling the deformation over the seismic cycle, such as interseismic locking, postseismic slip (afterslip), non-linear viscoelastic, and poroelastic relaxation. 2.) Estimation of the present-day spatial distribution of the slip budget, which is essential to calculate the magnitude and location of future earthquakes. 3.) Elucidating the ratio between seismic and aseismic slip to the total budget. 4.) Elucidating the role of pore-pressure changes on aftershocks in space and time, particularly those occurring on-shore in the crust.