Thumping Cycle Variations of Doublet Pool in Yellowstone National Park, USA

Doublet Pool is an active hydrothermal feature in Yellowstone National Park, USA. Approximately every half hour, it thumps for about 10 min due to bubbles collapsing at the base of the pool. To understand its thermodynamics and sensitivity to external factors, we performed a recurring multiple-year passive seismic experiment. By linking recorded hydrothermal tremor with active thumping, we determine the onset and end of thumping, and the duration of silence between each thumping cycle. The silence interval decreased from around 30 min before November 2016 to around 13 min in September 2018. This change followed unusual thermal activity on the surrounding Geyser Hill. On a shorter time scale, wind-driven evaporative cooling can lengthen the pre-thumping silence interval. Based on energy conservation, we determine the heating rate and heat needed to initiate thumping to be 3-7 MW and similar to 6 GJ, respectively.