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7月发生在南加州的里奇克雷斯特地震作出反应，并开发和测试一种监测地球应力及其在大地震后如何变化的工具。该项目利用全球定位系统和卫星雷达数据，在接近真实的时间内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，并在地震后立即进行测试。这个项目可能会导致未来的实时余震预报方法。在过去20年中，在南加州的第一次大地震提供了一个机会，以测试震后应力演变监测系统，将在近实时操作。通常计算地震主震的库仑应力变化，以检查触发附近断层地震的可能性。在距破裂约一个断层长度范围内的余震，可以很大程度上归因于同震应力变化，但在更远的距离上，由于震后更深层次的变形过程（如地幔流动）所引起的应力变化大于同震应力变化。里奇克雷斯特地震触发的余震距离主震100 km以上，与主震库仑应力变化不一致，通过本研究发展的近真实的时间技术有可能应用于未来的实时余震预报。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。震后变形计算是相对便宜的和套件的模型可以很容易地计算接近真实的时间。里奇克雷斯特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.