Reconstruction of Velocity Models using Combined DAS and Geophone Data at a Complex Urban Archaeological Site

Urban environments pose significant challenges for seismic imaging, especially where high resolution and minimal disturbance are crucial, such as in archaeological or civil engineering contexts. Distributed Acoustic Sensing (DAS) presents a modern alternative by turning standard fiber optic cables into dense seismic arrays, eliminating the need for conventional geophones. Originally applied in deep borehole settings for hydrocarbon exploration, DAS has yet to be fully tested in shallow, urban applications.

This study addresses that gap by deploying DAS at a complex urban archaeological site. In 2022, three shallow boreholes around the site were instrumented with fiber optics and paired with surface seismic nodes. Active and passive seismic surveys were conducted with two aims: integrating DAS with geophone data using first-arrival traveltime tomography to build P-wave (VP) models, and applying ambient noise interferometry to recover S-wave (VS) models.

The results show that combining DAS and conventional sensors in a hybrid system can achieve detailed subsurface imaging while being non-invasive and scalable. This approach offers a valuable tool for urban geophysical investigations, especially in sensitive heritage sites where traditional methods are impractical.