Tilt and self-potential observations of Kibedani Geyser, Japan: Relationship between fluid flow and CO2-driven geyser activity

Abstract Multi-parameter, multi-site observations were undertaken at the Kibedani Geyser, Japan, where the eruption of cold spring-water (20℃) is driven by underground CO2 pressure. Video, temperature, self-potential (SP), ground tilt, and acoustic observations were undertaken. Tilt and SP data display temporal changes related to the geyser cycle of 38 min (32 min between eruptions, with 6 min of eruption). Tilt data indicate that an inclined crack-shaped cavity pressure source expands between eruptions and contracts during eruption, with post-eruption re-expansion beginning ~2.5 min after eruption, when ground tremor has ceased. SP changes suggest groundwater inflow to the pressure source. We conclude that CO2 accumulates in the cavity, uplifting water for eruption. Tilt and SP multi-site observations were effective in estimating fluid flows associated with geyser activity.