Mara H. Reed , Anna Barth, Taka'aki Taira, Jamie Farrell, Michael Manga

When and why earthquakes trigger the eruption of magma, mud, and water remain unclear. On 18 September 2022, Steamboat Geyser in Yellowstone, USA erupted 8.25 hours after a local M3.9 earthquake. The distribution of Steamboat eruption intervals suggests a low probability of erupting so soon after the earthquake by chance. A seismometer 340 m from Steamboat recorded seismic waves with a peak ground velocity of 1.2 cm/s, which is the largest ground motion experienced in the area since at least March 2018 and is similar to values that have affected other Yellowstone geysers. Ambient seismic noise amplitude and relative seismic velocity changes in narrow frequency bands indicate a subsurface hydrothermal response. We find it likely that the eruption was earthquake-triggered. If so, the hours-long delay suggests that dynamic strains from seismic waves caused changes in subsurface permeability and flow paths that enabled eruption.