Krasheninnikov eruption facilitated by M8.8 Kamchatka earthquake and hidden critical state

James Hickey, Rami Alshembari, Lorenzo Mantiloni, Gilles Seropian, Yasser Maghsoudi, Gino Gonzalez, Brendan T. McCormick Kilbride, Ben Esse, Mike Burton

Large earthquakes can trigger volcanic eruptions, but the required conditions and mechanisms remain uncertain. Here, we investigate whether the August 2025 eruption of Krasheninnikov volcano, Russia, was facilitated by the July 29th, 2025, Mw 8.8 Kamchatka megathrust earthquake. InSAR observations from 2016 to 2025 show no pre-earthquake inflation and satellite SO2 data indicate no detectable pre-eruptive degassing, suggesting apparent pre-earthquake, and pre-eruption, volcanic quiescence. Following the earthquake, InSAR data reveal a dyke intrusion beginning August 1st, shortly before eruption onset on August 2nd. Deformation modelling indicates a ~3.2x107 m3 dyke fed by a ~6-km-deep reservoir containing compressible, gas-rich magma. Stress modelling shows that static seismic stress and strain changes were small, mechanically mixed, and unlikely to have directly caused the dyke intrusion and eruption. Dynamic stresses were larger, reaching ~1.0±0.6 MPa, but still probably insufficient to trigger direct magma reservoir failure. Instead, the prolonged earthquake shaking likely promoted time-dependent volatile exsolution, bubble growth, and eventual reservoir destabilisation in a system already mechanically susceptible to failure. We show that apparently quiescent volcanoes may conceal hidden critical states prone to seismic perturbation, particularly in extensional arc settings with volatile-rich magmas exposed to repeated megathrust earthquakes.