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

RAPID项目对南加州7月的里奇克莱斯特地震做出了反应，并开发和测试了一种工具，用于监测地球上的应力以及大地震后应力的变化。该项目利用GPS和卫星雷达数据，近乎实时地计算出地壳和上地幔是如何因主震和余震序列而变形的。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。该项目可为未来的余震实时预报方法提供参考。南加州近20年来的第一次大地震为测试震后应力演变监测系统提供了一个机会，该系统将在近实时的情况下运行。通常计算地震主震引起的库仑应力变化，以检查引发附近断层地震的可能性。已知在断裂一个断层长度范围内的余震在很大程度上可归因于同震应力变化，但在更大的距离上，由于更深的震后变形过程（如地幔流动）引起的应力变化大于同震应力变化。里奇克莱斯特地震引发了距离主震100公里以上的余震，这些余震与主震的库仑应力变化不一致。通过本研究开发的近实时技术在未来的余震实时预报中具有应用潜力。这种方法的一个优点是，计算震后变形所需的大量计算是预先计算和存储的。地震后变形计算相对便宜，并且可以很容易地实时计算出一套模型。里奇克雷斯特地震序列首次提供了利用现代大地测量数据测试应力演化监测系统的机会。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。

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.