Self-potential distributions computed from numerical simulation results of thermohydraulic processes within a volcanic body, after [17]. Cases “G-” and “G and T-” correspond to the conditions of “steady-state of topography-driven groundwater flow” and “100 years after continuous heating of central conduit below sea level”, respectively. For cases “-C”, a shallow conductor above the water table is assumed. For cases “-N”, the drag current in the unsaturated zone is neglected. The “W”-shaped SP profile observed at Izu-Oshima volcano is reproduced by case “G and T-C”. The sketch in the upper part of the figure illustrates the earth surface topography and the water table elevation.
