Probing the Dead Sea Fault with the First Wireline-Free Hybrid DAS-Accelerometer Array in an Abandoned Well

Abstract We deployed the first-of-its-kind wireline-free collocated vertical distributed acoustic sensing (DAS) fiber and borehole accelerometer in a 750-m-deep abandoned oil well near the Dead Sea Fault, an active plate boundary. A dense active-source survey combining surface geophones and DAS reveals the dynamics of the DAS signal. We observe seismic phases with moderate-to-high signal-to-noise ratio in the fluid-filled section of the borehole. Prominent tube waves are visible in its open portion. First-arrival tomography, in conjunction with surface sources and geophones, indicates high near-surface velocities, consistent with logging reports of shallow high-velocity basaltic layer overlying more heterogeneous sedimentary sequences. Our 10-day-long temporary installation enabled the detection of multiple previously uncatalogued microearthquakes (ML ≈ 1), using a PhaseNet automatic phase picker manually validated by DAS data. These results demonstrate that low-effort vertical DAS deployments in abandoned boreholes can enhance seismic imaging and microseismic monitoring at active tectonic regions, offering a high-resolution complementary scope to traditional borehole sensors.