EAR-PF: Earthquake triggering throughout the seismic cycle: a unified laboratory and seismological study

尼古拉斯·范德埃尔斯特博士被授予美国国家科学基金会地球科学博士后奖学金，将在哥伦比亚大学进行，研究地震成核和触发的物理。这项研究将结合观测地震学和实验室实验，将地震触发敏感性与断层上的应力状态联系起来。小地震通常是由远距离大地震的地震波引发的，这就是所谓的远程触发。对远程触发的敏感性因地区而异，在整个地震周期内，随着应力的积累，敏感性可能会增加。这项研究的目的是确定使断层对触发敏感的局部条件，并确定触发敏感性是否可以用作断层上的临界应力状态的指示器。这项研究的观测部分将使用地震波形来识别已知活动断层附近的触发地震。这一组成部分将利用最近在仪器设备良好的地区(例如日本东北附近)发生的大地震，我们现在知道这些地区的断层接近地震周期的末期。在实验室部件中，模拟的泥填充断层将受到地震波的影响，声波传感器将监测整个粘滑周期中触发敏感性的变化。这项工作解决了地震预测领域当前的一个主要挑战：如何在产生时变破裂概率时考虑弹性地震周期。这些结果将对负责识别地震危险的政府机构以及与地震风险管理有关的行业有用。该项目将为本科生在数字地震记录处理和实验岩石力学方面的培训创造机会。

Dr. Nicholas van der Elst has been awarded an NSF Earth Science Postdoctoral Fellowship, to be carried out at Columbia University, to study the physics of earthquake nucleation and triggering. This study will combine observational seismology and laboratory experiments to link earthquake triggering susceptibility to the stress state on the fault. Small earthquakes are commonly initiated by the seismic waves from distant large earthquakes, in what is called remote triggering. Susceptibility to remote triggering varies regionally, and may increase as stresses build throughout the seismic cycle. The purpose of this study is to identify the local conditions that make a fault susceptible to triggering, and to determine whether triggering susceptibility can be used as an indicator of a critical stress state on the fault. The observational component of this study will use seismic waveforms to identify triggered earthquakes near known active faults. This component will capitalize on the recent occurrence of large earthquakes in well-instrumented regions (e.g. off Tohoku, Japan), where we now know that faults were near the end of the seismic cycle. In the laboratory component, simulated gouge-filled faults will be subjected to seismic waves, and acoustic sensors will monitor for changes in triggering susceptibility throughout the stick-slip cycle.This work addresses a major current challenge in the field of earthquake forecasting: how to take the elastic earthquake cycle into account in producing time-varying rupture probabilities. The results will be of use to government agencies tasked with identifying seismic hazard as well as to industries concerned with managing seismic risk. This project will create opportunities to train undergraduate students in digital seismogram processing and experimental rock mechanics.