Insights into the complexities of a seismogenic subduction zone: Analysis of a high-quality aftershock data set from the 2017 Tehuantepec (M8.2) offshore Mexico earthquake

洞察孕震俯冲带的复杂性：2017 年墨西哥特万特佩克 (M8.2) 近海地震的高质量余震数据集分析

• 批准号: 2054442
• 负责人: Aaron Velasco
• 金额: $ 30.3万
• 依托单位: University of Texas at El Paso
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-15 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2054442&HistoricalAwards=false
• 关键词: Insights; into; complexities; seismogenic; subduction

Subduction zones – where one tectonic plate dives beneath another – are responsible for the most impactful natural hazards on the planet. Those include large earthquakes, tsunamis, and volcanic eruptions which at times are explosive. These destructive events present major threats to human societies. They often cause human casualties and economic losses. The Mexican subduction zone has been responsible for large, devasting earthquakes throughout the past century. It is marked by the Middle American Trench off the coast of Mexico. There, the Cocos Plate dives beneath the continental North American Plate. It was responsible for the September 7, 2017 Tehuantepec, Mexico earthquake of magnitude 8.2 on the Richter scale. Here, the researchers investigate what caused this destructive event. They use data collected by a rapid seismic-array deployment following the earthquake. Analyzing the high-resolution data, they gradually unveil subduction-zone processes and earthquake mechanisms. This project leverages an international partnership between the University of Texas at El Paso (UTEP) and several institutions in Mexico. It also provides training for graduate and undergraduate students, notably from groups underrepresented in science.Here the team analyze a high-quality, unique aftershock dataset from the 2017 Tehuantepec earthquake. The data were collected after a seismic deployment supported by a RAPID award. The RAPID network augmented permanent and temporary networks deployed by the Universidad Nacional Autónoma de Mexico (UNAM). It included ten broadband instruments deployed in early Oct. 2017 (that recorded data for 6 months) and 51 UTEP-owned Nodes (5-Hz, 3-component geophones, active for 22 days). During the broadband deployment, the Servicio Sismológico Nacional (SSN) recorded over 30,000 aftershocks. This highlights the robust nature of earthquake generation. The project goal is to answer fundamental and specific questions that relate to subduction zone processes. Fundamental questions, determined by community efforts, include: when and where do large earthquakes happen? How do spatial variations in subduction inputs affect seismicity and magmatism? How are surface processes linked to subduction? Specific questions about the Mexican subduction zone are: will the Tehuantepec earthquake load the upper plate and possibly trigger a large earthquake on the plate interface? Are the Tehuantepec and subsequent earthquakes linked? These earthquakes are the September 19, 2017 Morelos-Puebla, Mexico (M7.1), the February 18, 2018 Pinotepa Nacional, Mexico (M7.2), and the June 23, 2020 (M7.4) La Crucecita. To answer these questions, the researchers merge the various datasets which builds a foundation for five complementary approaches: 1) calculate a high-resolution aftershock dataset; 2) analyze seismicity and stress, 3) search for earthquake triggering mechanisms, 4) define the structure of the subduction zone, and 5) integrate results to address remaining questions. This project strengthens a strong collaboration between UTEP and, in Mexico, UNAM, the SSN, and the Universidad Autónoma de Ciudad Juárez.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.

俯冲带（一个构造板在另一个构造板上潜水）是造成地球上最具影响力的自然危害的原因。这些包括大地地震，海啸和火山喷发有时具有爆炸性。这些破坏性事件对人类社会构成了重大威胁。它们经常造成人类伤亡和经济损失。在过去的一个世纪中，墨西哥俯冲带负责大型，破坏性的地震。它的标志是墨西哥沿岸的中美洲沟渠。在那里，可可板在连续的北美板块下面潜水。它负责Richter量表2017年9月7日，墨西哥墨西哥8.2的地震。在这里，研究人员研究了导致这一破坏性事件的原因。他们使用地震后快速地震阵列部署收集的数据。分析高分辨率数据，它们逐渐揭示了俯冲区的过程和地震机制。该项目利用德克萨斯大学El Paso（UTEP）与墨西哥的几家机构之间建立了国际伙伴关系。它还为研究生和本科生提供培训，特别是来自科学领域不足的团体。在这里，团队分析了2017年Tehuantepec地震的高质量，独特的余震数据集。数据是在迅速奖励支持的地震部署后收集的。快速网络增强了由墨西哥大学NacionalAutónomade nacionalAutónoma（UNAM）部署的永久和临时网络。它包括在2017年10月初部署的十种宽带仪器（记录了6个月的数据）和51个UTEP拥有的节点（5 Hz，3组分的地球器，活跃22天）。在宽带部署期间，ServicioSismológicoNacional（SSN）记录了30,000多个余震。这突出了地震产生的强大本质。项目目标是回答与俯冲区流程相关的基本问题和具体问题。由社区努力确定的基本问题包括：大地震何时何地发生？俯冲输入的空间变化如何影响地震性和岩浆作用？表面过程如何与俯冲相关？关于墨西哥俯冲带的具体问题是：Tehuantepec地震会在板界面上加载上板并可能触发大地地震吗？ Tehuantepec和随后的地震是否联系在一起？这些地震是2017年9月19日，墨西哥莫雷洛斯·普布拉（M7.1），2018年2月18日，墨西哥Pinotepa Nacional（M7.2）和2020年6月23日（M7.4）La Crucecita。为了回答这些问题，研究人员合并了各种数据集，这些数据集为五种完整方法建立基础：1）计算高分辨率的余震数据集； 2）分析地震性和压力，3）寻找地震触发机制，4）定义俯冲带的结构，以及5）综合结果以解决剩余的问题。该项目强调了UTEP与墨西哥，UNAM，SSN和UniversidadAutónomaDeciudadJuárez之间的强有力的合作。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准通过评估而被认为是珍贵的支持。