Earthquake Location with Distributed Acoustic Sensing Subarray Beamforming with Implications for Earthquake Early Warning

Earthquake location is a crucial component of earthquake monitoring and earthquake early warning (EEW) systems. The emerging distributed acoustic sensing (DAS) technology allows array measurements of strain rate in an unprecedented spatial resolution and over long distances. Hence, it holds great promise for earthquake location evaluation. Yet, many existing fibers that are in use for seismological applications are of linear geometry and often result in ambiguous location estimation. Here, we show that time-domain beamforming and phase arrival-time difference, applied to many short DAS subarrays, can produce robust evaluations of source locations. The aggregation of beams and phase arrival times from many segments along the fiber constrains the epicenter location. We demonstrate the method using two local small-size earthquakes recorded on a 66 km fiber. We further show the method’s applicability for real-time EEW.