Lessons Learned from Seismic While Drilling with Diamond Core Drill Bits from ICDP Expedition 5071 in the Ivrea-Verbano Zone (Western Alps, Italy)

Seismic While Drilling (SWD) offers the possibility of imaging the subsurface in real time by using the drill bit as a seismic source. This research is part of the Drilling the Ivrea-Verbano zonE (DIVE) project, run as ICDP expedition 5071, and it examines the feasibility of using a diamond core drill bit for SWD in two boreholes (5071_1_A and 5071_1_B) in hard-rock conditions. Continuous seismic data were recorded with three-component MEMS sensor arrays. The aim was to determine the detectability of weak seismic signals from the drill bit at the surface. Advanced processing techniques, such as noise suppression, wavefield separation and cross-coherence interferometry were deployed, but no drill-bit signals could be reliably detected. Noise from the drill rig, generators, mud pumps, and general site activity dominated the recordings. This result highlights the fundamental challenges of SWD with weak sources in hard-rock environments. It also provides important lessons for future SWD campaigns, such as the quantification of detection limits for diamond core drilling, the need for noise mitigation, and the likely requirement of near-bit or downhole sensors.