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Cross-correlated ambient data recorded on a distributed acoustic sensing array

Citation

Mjehovich, Joseph; Jin, Ge; Martin, Eileen; Shragge, Jeffrey (2022), Cross-correlated ambient data recorded on a distributed acoustic sensing array, Dryad, Dataset, https://doi.org/10.5061/dryad.3j9kd51k9

Abstract

Distributed acoustic sensing (DAS) is a relatively new technology used in many geophysical applications. The versatility and high temporal-spatial resolution make DAS ideal for rapid deployment surveys such as earthquake-aftershock monitoring and hazard assessment. However, these applications often rely on trenched cable installations that are time consuming and cost prohibitive, or on existing telecom fibers that are limited in spatial coverage. We deploy a DAS array composed of six parallel linear subsections directly on ground surfaces with different conditions. We apply ambient interferometry and adopt a simplified spectral-analysis-of-surface waves (SASW) method to determine the average shear-wave velocity of the top 30 m (VS30). Our methodology results in robust VS30 estimates for each surface deployment subsection that are consistent with collocated 1 m-depth trenched cables. The implications of these findings support DAS as a viable method for non-invasive rapid deployment surface surveys for earthquake hazard assessment.

Methods

Approximately 1.0 hour of DAS data were recorded at the Colorado School of Mines campus on December 2nd, 2020 at a 4467 Hz sampling rate with a channel spacing of approximately 2.45 m. A gauge length of 4.0 times the channel spacing was used. We recorded hammer-shot data at 47 locations at the surface, as well as ambient waveforms from a nearby road. The attached data files are virtual shot gathers produced by applying seismic-noise interferometry to the raw DAS data. See manuscript for detailed description of methodology.

Usage Notes

The attached Jupyter Notebook and data files can be used to reproduce the results corresponding to the submitted manuscript "Rapid-surface deployment of a DAS system for earthquake hazard assessment".