Regolith and host rock influences on CO2 leakage: Active source seismic profiling across the Little Grand Wash fault, Utah

Understanding carbon dioxide (CO2) reservoir to surface migration is crucial successful capture and sequestration approaches; especially fault/reservoir interactions under injection pressure. Through seismic imaging, we explore regolith shallow stratigraphy across the Little Grand Wash fault. The presence of natural CO2 seeps, travertine tufa deposits confirm modern ancient fault-controlled leakage. We consider this an analogue for a long-failed site. estimate bulk porosity fracture density host rock, regolith, fault zone from petrophysical relationships. When combined with existing geochemical geological data, characterize 60 m wide damage that represents primary delivery channel originating depths. Within zone, low velocities suggest sediments have formed through rock chemical dissolution or mechanical weathering. In contrast, within adjacent are consistent clastic rocks. measure anomalously high along one profile best sealed (cemented/plugged) permeability, relic flow channel. This suggests permeability varies strike. While regional stress changes may account decadal- millennial-scale in pathways, speculate total fluid pressure has locally reduced fault's minimum horizontal effective stress; thereby producing both low- high-permeability segments either block promote migration. Studying system can inform potential risks future projects guide monitoring efforts.