Developing A Surface Distributed Acoustic Sensing (DAS) Data Processing in Comparison with Conventional Geophone Response for Near Surface Survey

Distributed Acoustic Sensing (DAS) is a novel technology in seismic measurement techniques that utilizes fiber optics as a receiver of acoustic waves. We provide the developed DAS strain rate response to evaluate surface DAS performance and process the geophone data, which is in particle velocity. The field data test investigates the effects of fiber coupling and the response of seismic sources. The survey was carried out at a test site, DAS data using a single-mode fiber buried in a shallow trench, using a vibroseis as an active seismic source and acquired in velocity mode. Subsequently, we applied a diverse preprocessing flow for DAS strain rate and geophone data through a conventional seismic processing framework. The observed amplitudes of DAS and Geophone shot records showed a slight difference in their mean spectrum. The DAS strain rate records from vibroseis are compared to observe the qualitative differences. Our findings suggest that a fiber optic cable buried in the trench is a promising coupling for shallow DAS imaging, as it can minimize ambience and optical noise. The observed DAS strain rate record showed good agreement with the theoretical expectations that are similar to a conventional geophone record. The frequency of vibroseis response can still be maintained for 20-120 Hz after cross correlation, as it is the same as the pilot sweep frequency and filtered using bandpass. Geophone data, in contrast, clearly distinguishes body and surface waves despite ambient noise. These findings highlight the potential of surface DAS for shallow seismic imaging and its comparability with geophone data, providing valuable insights for future survey designs.