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

当它们发生时，加州的大地震会造成数十亿美元的损失。随着每次地震事件的发生，人们对地震风险的认识不断提高，同时也伴随着进一步了解地震过程的科学努力。RAPID的动机是需要在2019年7月里奇克莱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施加压力。计划是安装6个延伸计，量化附近断层当前和未来滑动的可能性。每分钟采集一次数据，储存在联阿援助团供公众查阅。这项工作的动机是迫切需要在里奇克雷斯特地震序列的中震中心附近的活动断层上部署延伸计，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施加应力。在触发滑动之后，应力变化倾向于在附近断层上建立一个对数衰减的蠕变速率，可以使用敏感的延伸计进行测量。地震序列本身是一个级联的共轭断裂，其震级逐渐增大，随后是数千次较小的余震，因为附近的共轭断层晶格放松了震中应变。地震产生的动态应力范围极广，导致远至墨西哥边境的断层引发滑动。6个新的延伸计的部署是对现有延伸计的补充，现有延伸计在破裂两天后部署在地表破裂处。延伸计在2-4米范围内以2微米的精度记录滑动，每分钟采样一次，持续一年。延伸计将记录一年的滑动数据，这将允许计算速率变化，并搜索可用于确定断裂带流变条件的偶发滑动。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.