Collaborative Research: 3D Imaging of Controls on Subduction Zone Megathrust Rupture and Slip Behavior

合作研究：俯冲带巨型逆冲断裂和滑动行为控制的 3D 成像

• 批准号: 2321410
• 负责人: Susan Beck
• 金额: $ 24.14万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2321410&HistoricalAwards=false
• 关键词: Collaborative; Research; 3D; Imaging; Controls

The largest earthquakes worldwide occur in ‘subduction zones’ where plates under the oceans descend beneath continents and into Earth’s deep interior. These earthquakes, which occur on faults that separate the descending oceanic plate from the overlying continental plate, can have devastating human and economic impacts. Regions of the world at risk from these earthquakes include the U.S. Pacific Northwest and Alaska, Central and South America, Japan, and Southeast Asia. In this project, Meltzer, Beck, and their team will analyze data recorded by seismometers that they deployed in northern Ecuador between 2020 and 2022, in coordination with European scientists. Their analyses will result in detailed 3D images of the subduction zone beneath Ecuador, where a magnitude 7.8 earthquake occurred in 2016. Using machine learning techniques, the researchers will also comb the seismometer data for signs of small earthquakes, whose locations can outline the geometry of the main subduction zone fault and other local faults. The research team will use the images and earthquake data to infer which parts of the main subduction zone fault could give rise to large earthquakes. These findings and related activities by the research team and Ecuadoran colleagues will help Ecuador anticipate and plan for potentially devastating subduction zone earthquakes.Increasingly high resolution seismic studies reveal the complexity and diversity of structure and physical properties within and between subduction zones. Downdip and along-strike heterogeneity influences plate coupling and slip behavior on the plate interface, in the downgoing plate, and in the upper plate, ultimately culminating in large magnitude earthquakes with significant human and economic impacts. Between October 2020 and November 2022, the team collected onshore-offshore active and passive seismic data recorded by a dense array of 3-component short period nodes and broadband sensors in coastal Ecuador. These data were acquired as a complement to the HIPER project (High Resolution Imaging of the Pedernales Earthquake Rupture Zone) supported by French and German funding agencies. The data were collected in and adjacent to the 2016 Mw 7.8 Pedernales rupture zone to significantly densify the onshore portion of HIPER for active-source recording, and to widen the aperture of passive recording to improve lateral coverage and imaging at depth across the forearc. The combined arrays present an exceptional opportunity for multiscale 3D imaging to examine the relationship between physical properties, structure, fluids, and variations in slip behavior from seismic to aseismic. Analysis of these data will employ machine learning to significantly increase source detection, and a combination of traveltime and ambient noise tomography and high frequency receiver functions as input to a multi-step series of inversions to constrain earthquake locations and seismic structure along and above the seismogenic zone and across the forearc.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.

全世界最大的地震发生在“俯冲区”，海洋下方的盘子降落在大陆下，进入地球深内部。这些地震发生在将下降的海洋板与上覆的连续板上区分开的断层，可能会产生毁灭性的人类和经济影响。来自这些地震的世界风险地区包括美国太平洋西北部和阿拉斯加，中部和南美，日本和东南亚。在这个项目中，梅尔策，贝克及其团队将分析他们在2020年至2022年之间在北厄瓜多尔部署的地震仪记录的数据，并与欧洲科学家协调。他们的分析将导致厄瓜多尔下方的俯冲带的详细3D图像，该图在2016年发生了7.8级地震。使用机器学习技术，研究人员还将梳理地震仪数据以获取小地震的迹象，其位置可以概述主俯冲区断层和其他当地故障的几何形状。研究小组将使用图像和地震数据来推断主要俯冲区故障的哪些部分可能导致大地震。研究团队和厄瓜多尔同事的这些发现和相关活动将有助于厄瓜多尔预期并计划潜在的俯冲区地震。高分辨率地震研究揭示了俯冲区域内和之间结构和物理性质的复杂性和多样性。倾斜和沿形的异质性影响板界面，下板和上板上的板耦合和滑动行为，最终在大范围内达到了具有重大人类和经济影响的大范围地球地震。在2020年10月至2022年11月之间，该团队收集了陆上岸的活跃和被动的地震数据，该数据由沿海厄瓜多尔的3组成分短期节点和宽带传感器记录。这些数据被作为法国和德国资助机构支持的赫普项目（Pedernales地震破裂区的高分辨率成像）的完成。数据收集在2016 MW 7.8 PEDERNALES破裂区域中，以显着使赫普的岸上部分保持活跃源记录，并扩大被动记录的光圈，以改善跨前期深度的横向覆盖范围和成像。组合的阵列为多尺度3D成像提供了一个非凡的机会，以检查物理性质，结构，流体和滑移行为从地震抗性到无向抗性之间的关系。对这些数据的分析将采用机器学习来显着增加源检测，并且旅行时间和环境噪声层析成像和高频接收器的结合起作用，作为一系列多步倒置的输入，以限制地震地点和地震结构沿线和地震结构，沿着地震区域和高于地震区域的地震结构，并在跨越的范围内进行了众多范围。 标准。