Collaborative Research: RAPID: Using the M6.4-7.1 Ridgecrest, CA Earthquake sequence to test a postseismic stress evolution monitoring system

RAPID 项目响应 7 月份南加州里奇克莱斯特地震，开发并测试了一种工具来监测地球应力及其在大地震后的变化。该项目获取 GPS 和卫星雷达数据，并近乎实时地计算地壳和上地幔如何因主震和余震序列而变形。该项目支持两名研究生开发这些新工具并在地震发生后立即对其进行测试。该项目可能会带来未来的实时余震预报方法。过去 20 年来加利福尼亚州南部的第一次大地震为测试近实时运行的震后应力演化监测系统提供了机会。常规计算地震主震引起的库仑应力变化，以检查在附近断层上引发地震的可能性。我们知道，在破裂大约一断层长度范围内的余震很大程度上可以归因于同震应力变化，但在更大的距离上，由于地幔流等更深的震后变形过程引起的应力变化大于同震应力变化。 Ridgecrest地震引发了距离主震超过100公里的余震，这些余震与主震的库仑应力变化不一致。通过这项研究开发的近实时技术有可能在未来的实时余震预报中得到应用。这种方法的优点是计算震后变形所需的大部分繁重计算都是预先计算和存储的。震后变形计算相对便宜，并且可以轻松地近乎实时地计算模型套件。里奇克莱斯特地震序列首次提供了利用现代大地测量数据来测试应力演化监测系统的机会。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

The RAPID project responds to the July Ridgecrest earthquakes in Southern California and develops and tests a tool to monitor stress in the Earth and how it changes after large earthquakes. The project takes GPS and satellite radar data and in near real time computes how the Earth's crust and upper mantle are deforming from the mainshocks and aftershock sequences. This project supports two graduate students to work on developing these new tools and testing them in the immediate aftermath of an earthquake. This project could lead to a future real-time aftershock forecasting method.The first major earthquake in southern California in the last 20 years provides an opportunity to test a postseismic stress evolution monitoring system that would operate in near-real time. Coulomb stress changes from the mainshock of an earthquake are routinely computed to examine the potential for triggering earthquakes on nearby faults. It is known that aftershocks within about one fault-length of the rupture can largely be attributed to coseismic stress changes, but at larger distances, stress changes due to deeper postseismic deformation process such as mantle flow are larger than the coseismic stress change. The Ridgecrest earthquake triggered aftershocks greater than 100 km from the mainshock that are not consistent with Coulomb stress changes from the mainshock.The near real time technique developed through this research has potential to be implemented in future real-time aftershock forecasting. An advantage of this approach is that much of the heavy computation required to compute postseismic deformation is pre-computed and stored. The postseismic deformation calculations are relatively inexpensive and suites of models can be easily computed near real time. The Ridgecrest earthquake sequence provides the first opportunity with modern geodetic data to test a stress evolution monitoring system.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.