Collaborative Research: Investigating the role of dynamic strain fields in earthquake triggering processes by simulating full wavefield with 3D seismic velocity structures

合作研究：通过使用 3D 地震速度结构模拟全波场来研究动态应变场在地震触发过程中的作用

• 批准号: 2022441
• 负责人: Wenyuan Fan
• 金额: $ 32.08万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2022441&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; role; dynamic

Observations of earthquakes caused by perturbations from other earthquakes, both close by and far away, are important for understanding how earthquakes happen and the mechanisms that trigger them. Triggered earthquakes caused by passing seismic waves suggest that earthquake processes are not completely random and independent on disconnected faults. For example, the 2002 Denali magnitude 7.9 earthquake in Alaska triggered abundant earthquakes in the western US. Why do earthquakes correlate with the passing seismic waves, and how do these tiny ground motions cause earthquakes? A better understanding of such processes will help our fundamental understanding of complex earthquake rupture processes and will aid in mitigating seismic hazards by accurately assessing where and when the next earthquake may occur. This project will take advantage of newly developed computational tools and characterizing the relationships between the patterns of the triggered earthquakes and the waves generated by distant earthquakes. The project will develop a new statistical approach to identify triggered earthquakes in southern California and the Caribbean region. The spatial and temporal evolutions of these triggering responses will be examined across multiple fault systems in these regions of interest. The project supports a collaboration between scientists at the University of California, San Diego and the University of Miami. Graduate students, undergraduate students, and postdoctoral fellows will all participate in the project. The work will be of broad interest to those who study earthquakes and their associated hazards. Major earthquakes frequently dynamically trigger seismic events at multiple disconnected faults up to thousands of kilometers away. The correlation between the passing seismic waves and triggered seismicity is robust yet puzzling. A key challenge in understanding dynamic triggering is comparatively characterizing the realistic dynamic strain fields at seismogenic depth and how the associated elevated seismicity evolves through time and space. This project aims to systematically model dynamic strain fields of earthquake sequences and their relation to dynamically triggered earthquakes within a framework of heterogeneous 3D seismic velocity media. The primary goal of the project is to investigate the time-dependent fault zone stress state and fault zone material properties. The project will first identify dynamic triggering cases in southern California and the Caribbean region by developing a new statistical approach that uses distributions of statistics instead of the statistics solely to find significant cases. The project will then simulate realistic dynamic strain fields of these cases with high-resolution 3D velocity models and the SPECFEM 3D algorithms. The project plans to develop a high-resolution body wave velocity model and earthquake catalogs for the Caribbean region. A central element of this work is using the spatiotemporal migration patterns of regional seismicity as tracers of the evolving stress state and material characteristics and cross-examining these patterns with characteristics of the full dynamic wavefields.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.

对近处和远处其他地震扰动引起的地震的观测对于了解地震如何发生以及引发地震的机制非常重要。由经过的地震波引发的地震表明，地震过程并非完全随机且独立于不相连的断层。例如，2002年阿拉斯加迪纳利7.9级地震引发了美国西部地区的多次地震。为什么地震与经过的地震波相关，这些微小的地面运动如何引起地震？更好地了解这些过程将有助于我们对复杂的地震破裂过程有基本的了解，并有助于通过准确评估下一次地震可能发生的地点和时间来减轻地震灾害。该项目将利用新开发的计算工具，并表征引发的地震模式与远距离地震产生的波浪之间的关系。该项目将开发一种新的统计方法来识别南加州和加勒比地区引发的地震。这些触发响应的空间和时间演变将在这些感兴趣区域的多个断层系统中进行检查。该项目支持加州大学圣地亚哥分校和迈阿密大学科学家之间的合作。研究生、本科生和博士后都将参与该项目。这项工作将引起研究地震及其相关灾害的人们的广泛兴趣。大地震经常动态地在数千公里外的多个不相连的断层处引发地震事件。传递的地震波与触发的地震活动之间的相关性很强，但令人费解。理解动态触发的一个关键挑战是比较表征地震发生深度处的真实动态应变场以及相关的高地震活动如何随时间和空间演变。该项目旨在系统地模拟地震序列的动态应变场及其与异质 3D 地震速度介质框架内动态触发地震的关系。该项目的主要目标是研究随时间变化的断层带应力状态和断层带材料特性。该项目将首先通过开发一种新的统计方法来确定南加州和加勒比地区的动态触发案例，该方法使用统计数据的分布而不是仅仅使用统计数据来查找重大案例。然后，该项目将使用高分辨率 3D 速度模型和 SPECFEM 3D 算法模拟这些情况的真实动态应变场。该项目计划为加勒比地区开发高分辨率体波速度模型和地震目录。这项工作的核心要素是使用区域地震活动的时空迁移模式作为不断变化的应力状态和材料特征的示踪剂，并用全动态波场的特征交叉检查这些模式。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。

项目成果

Characteristics of Frequent Dynamic Triggering of Microearthquakes in Southern California

南加州微震频繁动力触发特征

• DOI: 10.1029/2020jb020820
• 发表时间: 2021-01
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Fan, Wenyuan;Barbour, Andrew J.;Cochran, Elizabeth S.;Lin, Guoqing
• 通讯作者: Lin, Guoqing

Ubiquitous Earthquake Dynamic Triggering in Southern California

南加州无处不在的地震动力触发

• DOI: 10.1029/2023jb026487
• 发表时间: 2023-06
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: DeSalvio, Nicolas D.;Fan, Wenyuan
• 通讯作者: Fan, Wenyuan

Space–Time Asymmetry in Earthquake Pairs along the Central San Andreas Fault: Evidence for Small Earthquake Links at Long Distances

中央圣安德烈亚斯断层地震对的时空不对称性：远距离小地震关联的证据

• DOI: 10.1785/0320230002
• 发表时间: 2023-04
• 期刊: The Seismic Record
• 作者: Shearer, Peter M.;Fan, Wenyuan
• 通讯作者: Fan, Wenyuan

Immediate Foreshocks Indicating Cascading Rupture Developments for 527 M 0.9 to 5.4 Ridgecrest Earthquakes

立即前震表明 527 M 0.9 至 5.4 Ridgecrest 地震的级联破裂发展

• DOI: 10.1029/2021gl095704
• 发表时间: 2021-10-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Haoran Meng;W. Fan
• 通讯作者: W. Fan

Fast rupture of the 2009 M w 6.9 Canal de Ballenas earthquake in the Gulf of California dynamically triggers seismicity in California

2009 年加利福尼亚湾 6.9 级 Canal de Ballenas 地震的快速破裂动态触发了加利福尼亚州的地震活动

• DOI: 10.1093/gji/ggac059
• 发表时间: 2022-03
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Fan, Wenyuan;Okuwaki, Ryo;Barbour, Andrew J;Huang, Yihe;Lin, Guoqing;Cochran, Elizabeth S
• 通讯作者: Cochran, Elizabeth S