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Efficient Localization of Microseismic Clusters Using DAS

Session: Fiber-Optic Seismology I [Poster]

Type: Poster

Date: 4/23/2021

Presentation Time: 11:30 AM Pacific

Description: 

Efficient detection and localization of seismic activity is a key research topic in microseismic monitoring. Distributed Acoustic Sensing (DAS) is explored as a monitoring measurement technique, as it provides a dense sampling in space capable of capturing the wavefield such that it may provide better earthquake detection and localization. Since DAS acquires substantial data volumes and measures strain predominantly in the axial direction of the fiber, it demands new and efficient techniques to localize the detected earthquakes.

We adapt a novel earthquake localization method to DAS data, that is based on a protein structure determination method from biochemistry (HADES¹). This method has already been proven successful for a single seismic station approach. The inputs are the distances between earthquakes and a seismic station, which are used to compute the inter-event distance. In this way, it is possible to find the relative position of earthquakes within a cluster. Four events with known locations are then required to retrieve the correct absolute position of this cluster. DAS measurements can extend this method to a line of densely spaced channels that allows for more accurate computation of the relative distances. We improve the method to obtain the absolute position and orientation of the earthquake cluster relative to the fiber-optic cable, by eliminating the need for master events. This is done by conducting a grid search to minimize the L2-norm between the observed and calculated Ts-Tp, where Ts and Tp are the S- and P-wave first arrival times, respectively. The method is tested first on synthetic data and later applied on a real data application.

¹ HADES: https://github.com/wulwife/HADES

Presenting Author: Katinka B. Tuinstra

Student Presenter: Yes

Authors