Response of Geofluid Systems to the Activation of Regional Seismicity in Kamchatka in July 2025

Geofluid systems are unique geomechanical sensors, as they can generate earthquakes themselves and also respond to changes in Earth activity. The MW = 8.8 earthquake of July 29, 2025 in Kamchatka was accompanied by numerous geofluid anomalous phenomena: (1) regional seismogenic faults activity; (2) significant post-seismic decreases in water levels (the first meters) and rates in wells of low temperature geothermal fields (Vilyuchinsky, Paratunsky and Ketkinsky); (3) omissions of eruptions of the Bolshoy geyser (Valley of Geysers) and the emergence of a new geyser-well (Kumroch); (4) the beginning of volcanic eruptions (Krasheninnikov volcano for the first time in ∼600 years, Klyuchevskoy volcano) and volcanoes activity increase (Karymsky, Mutnovsky, Kambalny). In this study, the ability of geofluid systems to track seismic events was used to identify the activity of regional seismogenic faults and volcanic magmatic systems (the Frac-Digger method). This provides an explanation for the observed phenomena in terms of the geomechanical regional stretching of Kamchatka, which was associated with an MW = 8.8 earthquake followed by a decrease in geofluid pressure. In magma systems of volcanoes, this triggered boiling and gas-lift of magma with subsequent eruptions. In the fractured-type reservoirs of low-temperature hydrothermal systems, this led to a significant drop in water levels and a cessation of discharge. In the high-temperature and gas-rich Valley of the Geysers Field, this led to the disintegration of the caprock and the infiltration of water, resulting in the subsequent eruptions of the Grotto and the Great Geyser being skipped, while the Kumroch CO2 reached the hydrothermal reservoir, boiled, and began cycling eruptions. These phenomena are consistent with the models of the MW = 8.8 earthquake’s focal mechanism and satellite geodetic data from GNSS and InSAR.