RAPID - Afterslip and triggered slip associated with the Ridgecrest earthquake sequence

RAPID - 与 Ridgecrest 地震序列相关的后滑和触发滑移

• 批准号: 1941558
• 负责人: Roger Bilham
• 金额: $ 3.71万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1941558&HistoricalAwards=false
• 关键词: RAPID; Afterslip; triggered; slip; associated

When they occur, major California earthquakes result in billions of dollars damage. Greater awareness of earthquake risk follows each event, and also accompanies scientific efforts to further understand seismic processes. This RAPID is motivated by the need to quickly deploy instruments on active faults near the July 2019 Ridgecrest earthquakes to determine how the earthquake have stressed nearby active faults. The plan is to install six extensometers and to quantify the potential for present and future slip on nearby faults. Data will be acquired once per minute and stored for public access at UNAVCO.This works is motivated by the need to urgently deploy extensometers on active faults near the meizzocenter of the Ridgecrest earthquake sequence to determine whether, and how, stress changes in the earthquake have stressed nearby active faults. Stress changes tend to set up a logarithmically decaying creep rate on nearby faults following triggered slip that can be measured using sensitive extensometers. The seismic sequence itself was a cascade of conjugate ruptures with progressively greater magnitude followed by thousands of smaller aftershocks as a nearby lattice of conjugate faults relaxed epicentral strain. The dynamic stresses from the earthquakes had extreme reach, causing slip to be triggered on faults as far south as the Mexican border. The deployment of 6 new extensometers supplement and existing one deployed across the surface rupture two days after rupture. The extensometers record slip with an accuracy of 2 micrometer over a range of 2-4 meters and sample once per minute for a year. The extensometers will record slip data for a year, which will allow for calculating rate changes and to search for episodic slip that can be used to determine rheological conditions in the fault zone.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.

当它们发生时，加州的大地震会造成数十亿美元的损失。随着每一次地震的发生，人们对地震风险的认识也随之提高，同时也伴随着科学工作的开展，以进一步了解地震过程。这种快速的动机是需要在2019年7月里奇克雷斯特地震附近的活动断层上快速部署仪器，以确定地震如何对附近的活动断层造成压力。该计划是安装六个引伸计，并量化目前和未来的潜在滑动附近的故障。每分钟将采集一次数据，并储存在联合国志愿人员办事处供公众查阅，这项工作的动机是需要在里奇克雷斯特地震序列的中间中心附近的活动断层上紧急部署伸缩计，以确定地震中的应力变化是否以及如何对附近的活动断层造成压力。应力变化往往会在触发滑动后的附近断层上建立一个动态衰减的蠕变速率，可以使用灵敏的引伸计测量。地震序列本身是一系列共轭破裂，震级逐渐增大，随后是数千次较小的余震，因为附近的共轭断层晶格使震中应变放松。地震产生的动应力范围很大，导致断层在南部远至墨西哥边境的地方发生滑动。部署6个新的引伸计补充和现有的一个部署在整个表面破裂后两天破裂。引伸计在2-4米的范围内以2微米的精度记录滑动，每分钟取样一次，持续一年。伸长计将记录一年的滑动数据，从而可以计算速率变化并搜索可用于确定断层带流变条件的阶段性滑动。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

项目成果

The July 2019 Ridgecrest, California, Earthquake Sequence Recorded by Creepmeters: Negligible Epicentral Afterslip and Prolonged Triggered Slip at Teleseismic Distances

蠕变仪记录的 2019 年 7 月加利福尼亚州里奇克莱斯特地震序列：可忽略不计的震中余滑和远震距离处的长时间触发滑移

• DOI: 10.1785/0220190293
• 发表时间: 2020
• 期刊: Seismological Research Letters
• 影响因子: 3.3
• 作者: Bilham, Roger;Castillo, Bryan
• 通讯作者: Castillo, Bryan