Rapid Response to the 2019 Ridgecrest Earthquake With Distributed Acoustic Sensing

Rapid seismic deployments after major earthquakes often produce critical data for characterizing postseismic processes. Taking advantage of pre‐existing optical fibers, the recently emerging distributed acoustic sensing (DAS) technology can quickly establish ultra‐dense seismic arrays after the mainshocks. Here we present the first example of such a rapid‐response experiment using four telecommunication fiber optic cables near the 2019 M 7.1 Ridgecrest earthquake in California. By applying template matching to the Ridgecrest DAS array, we detected 6 times more aftershocks than the standard catalog within the three‐month period. The enhanced catalog reveals abundant aftershocks on multiple crosscutting faults near the epicenters of the mainshock and the M 6.4 foreshock. Given the widespread fiber optic networks around the world, DAS has the potential to deliver fast and high‐resolution aftershock monitoring and promote better understanding of earthquake physics.