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

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.