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Comparing Near and Far Field Das Fiber Response for Monitoring Applications

Description: 

Distributed acoustic sensing data is increasingly used to monitor anthropogenic seismoacoustic sources. Previous work using chemical explosions for seismic and/or acoustic sources has shown that the seismoacoustic time series of the explosion-generated wavefield recorded on fiber does not match that from co-located geophones in the near-field. Conversely, the recorded wavefield time series does correlate well at far-field distances. Understanding the fiber response is critical for processing and analyzing this type of time series data. In this study we test if the poor correlation in the near-field is caused by incoherence at the scale of the gauge length and non-planar wavefront geometries. We analyze data recorded on co-located geophones, fiber, and seismic gradiometers to quantify the distances where the planar wavefront approximation becomes valid, resulting in coherent phase arrivals along the DAS gauge length. Our results may inform future fiber applications, particularly in cases where well-calibrated amplitudes are necessary. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Session: Exploiting Explosion Sources: Advancements in Seismic Source Physics [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: A. Christian Stanciu

Student Presenter: No

Invited Presentation: 

Authors