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月份的里奇克雷斯特地震做出反应，并开发和测试了一种工具，用于监测地球上的应力及其在大地震后的变化。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如何因主震和余震序列而变形。该项目支持两名研究生致力于开发这些新工具，并在地震后立即对其进行测试。该项目可能导致未来的实时余震预报方法。过去20年来，加利福尼亚州南部发生的第一次大地震为测试震后应力演变监测系统提供了机会，该系统将近实时运行。通常会计算地震主震的库仑应力变化，以检查在附近断层上触发地震的可能性。断裂带一个断层范围内的余震在很大程度上可以归因于同震应力的变化，但在更远的距离上，地幔流动等更深层次的震后变形过程引起的应力变化要大于同震应力变化。Ridgecest地震引发的余震距离主震100公里以上，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有可能在未来的实时余震预报中实施。这种方法的一个优点是，计算震后变形所需的大量计算都是预先计算和存储的。震后变形计算相对便宜，而且可以很容易地近乎实时地计算成套模型。Ridgecrest地震序列提供了第一次利用现代大地测量数据测试应力演变监测系统的机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.