CAREER: Assimilation of Geodetic Data in Physical Models of Subduction Zones

职业：俯冲带物理模型中大地测量数据的同化

• 批准号: 1848192
• 负责人: Sylvain Barbot
• 金额: $ 54.9万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1848192&HistoricalAwards=false
• 关键词: CAREER; Assimilation; Geodetic; Data; Physical

Earthquake and tsunami hazards represent significant threats to society. They threaten large population centers, notably around the Ring of Fire in Asia and across the Pacific. As direct observations of past seismic events are limited, mitigation of the associated risks hinges on the understanding of the underlying physics. Here, the researchers develop realistic computer simulations of the largest earthquakes on Earth. Those occur at subduction zones, a type of tectonic-plate boundary where one plate slides under another and sinks into the mantle. The team examines the interactions between shallow and deep deformation processes within the Earth. The goal is to better predict how the surface deforms before, during, and after large earthquakes. The researchers also study how earthquakes at subduction zones generate tsunamis. This type of calculations is challenging because it must account for the shape of the plate-boundary fault and for the variations of rocks' properties in space and time. Furthermore, it must encompass different timescales from the short earthquake duration (a few seconds or minutes) to the thousands of years of Earth's slow deformation in the context of plate tectonics. The simulations give a framework to understand numerous observations worldwide from seismic instruments and the Global Positioning System (GPS). This project provides support to a graduate student and a postdoctoral associate, training for two undergraduate students and outreach to local schools and the public. It also promotes the development of open-source software made freely available to the scientific community, as well as that of teaching material at the undergraduate and graduate level. This work, thus, advances numerical modeling of the solid earth and contribute to a safer, more educated and resilient society. This project aims to understand the seismic cycles at subduction zones and how megathrust slip and mantle flow interact. Subduction zones around the Ring of Fire have produced among the largest historical earthquakes. Expansive ruptures spreading along a low-angle subducting slab that cut through the continental crust generate great (Mw8) and giant (Mw9) earthquakes. Such earthquakes impact the viscoelastic flow at greater depths, which may induce rapid changes in regional sea levels. Here, the researchers build comprehensive numerical models for three chosen subduction zones in Japan, Sumatra and Chile. The models incorporate realistic morphology and material properties. They account for the evolution of friction on the megathrust and the effective viscosity in the surrounding rocks (oceanic asthenosphere and mantle wedge); inputs are based on laboratory results on rocks' friction and plastic flow. Outputs reproduce a wide range of observed slip behaviors, including slow-slip events, low-frequency earthquakes, slow and fast earthquakes, and tsunami earthquakes. The project outcomes include state-of-the-art open-source software to model the seismic cycle and surface deformation. The project results are integrated into teaching materials and activities for local-school and university students, and the public. The team also organizes workshops to train modeling practitioners.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地震和海啸灾害是对社会的重大威胁。它们威胁着大型人口中心，特别是亚洲和太平洋的火环地区。由于对过去地震事件的直接观测有限，减轻相关风险取决于对潜在物理学的理解。在这里，研究人员开发了地球上最大地震的逼真计算机模拟。这些发生在俯冲带，一种类型的构造板块边界，其中一个板块滑到另一个板块之下并沉入地幔。该小组研究了地球内部浅层和深层变形过程之间的相互作用。目的是更好地预测地表在大地震之前、期间和之后如何变形。研究人员还研究了俯冲带的地震是如何产生海啸的。这种类型的计算具有挑战性，因为它必须考虑板块边界断层的形状以及岩石性质在空间和时间上的变化。此外，它必须包括不同的时间尺度，从短地震持续时间（几秒钟或几分钟）到板块构造背景下地球缓慢变形的数千年。模拟提供了一个框架，以了解世界各地的地震仪器和全球定位系统（GPS）的众多观测。该项目为一名研究生和一名博士后助理提供支助，为两名本科生提供培训，并与当地学校和公众开展外联活动。它还促进开发免费提供给科学界的开放源码软件以及本科生和研究生一级的教材。因此，这项工作推进了固体地球的数值建模，并有助于建立一个更安全，更有教育和更有弹性的社会。本项目旨在了解俯冲带的地震周期以及巨型逆冲断层滑动和地幔流如何相互作用。火山带周围的俯冲带已经产生了历史上最大的地震。膨胀破裂沿着低角度俯冲板片扩展，切割大陆地壳，产生大（Mw 8）和巨型（Mw 9）地震。这种地震影响更深处的粘弹性流，可能导致区域海平面的快速变化。在这里，研究人员为日本，苏门答腊和智利的三个选定的俯冲带建立了全面的数值模型。模型结合了逼真的形态和材料特性。它们解释了大型逆冲断层上摩擦力的演变和周围岩石（海洋软流圈和地幔楔）的有效粘度;输入是基于岩石摩擦力和塑性流动的实验室结果。输出再现了广泛的观察到的滑动行为，包括慢滑事件，低频地震，慢和快地震，海啸地震。项目成果包括最先进的开放源码软件，用于模拟地震周期和地表变形。该项目的成果被纳入为地方学校和大学学生以及公众编写的教材和开展的活动。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

项目成果

Community‐Driven Code Comparisons for Three‐Dimensional Dynamic Modeling of Sequences of Earthquakes and Aseismic Slip

• DOI: 10.1029/2021jb023519
• 发表时间: 2021-11
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Junle Jiang;B. Erickson;Valère Lambert;J. Ampuero;R. Ando;S. Barbot;C. Cattania;Luca Dal Zilio;B. Duan;E. Dunham;A. Gabriel;N. Lapusta;Duo Li;Meng Li;Dunyu Liu;Yajing Liu;S. Ozawa;C. Pranger;Y. van Dinther

Rupture styles linked to recurrence patterns in seismic cycles with a compliant fault zone

破裂类型与顺应断层带地震周期中的复发模式相关

• DOI: 10.1016/j.epsl.2022.117593
• 发表时间: 2022
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Nie, Shiying;Barbot, Sylvain
• 通讯作者: Barbot, Sylvain

Structural control and system-level behavior of the seismic cycle at the Nankai Trough

• DOI: 10.1186/s40623-020-1145-0
• 发表时间: 2020-03
• 期刊: Earth, Planets and Space
• 作者: Q. Shi;S. Barbot;S. Wei;P. Tapponnier;T. Matsuzawa;B. Shibazaki

Physics of Megathrust Earthquakes: Introduction

• DOI: 10.1007/s00024-019-02308-y
• 发表时间: 2019-09
• 期刊: Pure and Applied Geophysics
• 影响因子: 2
• 作者: S. Barbot

Static Source Properties of Slow and Fast Earthquakes

• DOI: 10.1029/2019jb019028
• 发表时间: 2020-12
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: P. Nanjundiah;S. Barbot;S. Wei