Investigating the Changes in Periodicity of the CO₂-Driven Cold-Water Geyser Eruptions Through Field Observation at Tenmile Geyser, Utah

CO₂-driven cold-water geysers periodically ejecting cold water are rare. Although coalescence and expansion of ascending CO₂ bubbles can explain the eruption process, the triggering conditions and eruption cycle remain unclear. To clarify the triggering conditions, hydrostatic pressure in the well was decreased by pumping to induce eruptions. All four pumping tests successfully induced eruptions by decreasing the pressure of ∼10⁴ Pa. In the absence of artificial perturbations, similar reductions in pressure were observed during the intervals between two consecutive eruptions (IBEs). During IBE, the atmospheric pressure (P_air) and temperature (T_air) controlled the generation of the CO₂ bubbles which directly induced the pressure reduction in the well. Especially under the persistent low P_air and high T_air, the length of IBE showed a minimum value of 3.90 hr during field observations. We suggest that the atmospheric perturbations are the causes of the changes in geyser periodicity, given consistent geological and hydraulic conditions.