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Comparisons Between Geophone Array and DAS Array Detections

Description: 

We applied an array-based detector on 14-days of continuously recorded Distributed Acoustic Sensing (DAS) and co-located nodal geophone array data. These data were repurposed from the 2016 PoroTomo experiment at Brady’s Hot Springs, Nevada (e.g., Feigl et al., 2019). Since DAS is essentially a single component seismometer, we used a time-domain delay and sum technique modified to beamform only channels along linear portions of the fiber-optic cable with the highest coherency to measure the energy distribution in slowness space. The energies for each linear portion are then summed together to produce a final slowness image. We applied a moving window array detector on the geophone array using an optimal 1-3 Hz bandpass filter. The optimal DAS bandpass filter was 0.5-2 Hz. DAS was poor at estimating P- and S-wave BAZ and slowness compared to geophone array; however, we predicted using synthetics that the DAS array selected has cable broadside sensitivities. Future experiments using different fiber-optic cable geometries should provide better BAZ estimates. A persistent night-time local noise source toward the southwest was also observed by both geophone array and DAS. We correlated the duration of the noise signals to pumping schedules at the geothermal plant. Overall, the DAS and geophone array detection performance was similar over regional and teleseismic distances with the exception that DAS has many more false detections. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-858924.

Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Gene

Student Presenter: No

Invited Presentation: 

Authors