Formation of the hydrothermal system in Geysers Valley (Kronotsky Nature Reserve, Kamchatka) and triggers of the Giant Landslide

The Geysers Valley hydrothermal system is hosted within a system of two permeable faults (revealed by mapping thermal features), located above a suggested partially melted magmatic body and recharged by meteoric water along the outcrops of rhyolite–dacite extrusions. Fast erosion is stimulating the significant discharge rate, the geyser’s cycling mode and landslide events. Natural state thermal hydrodynamic modeling shows that 20–30 ka of high temperature upflow of 250 kg/s and an enthalpy of 900 kJ/kg could build up the hydrothermal system in the Geysers Valley basin with output discharge parameters comparable to those at the current level. Modeling also shows that steam accumulation below an inclined caprock may have hydrothermal eruption potential. The Giant Landslide took place on June 3, 2007, when 20 × 106 m3 of rocks were shifted 2 km downstream, more than 23 geysers were buried or submerged, and Podprudnoe Lake was dammed, injecting cold water into submerged geysers. Possible triggers of the Giant Landslide include the inclination of the sliding plane towards the Geysernaya river basin, a pressure increase in the fluid-magma system, hanging block saturation by water during spring flooding, hydrothermal alteration weakening of the sliding plane, and steam explosions. Recent geysers cycling activity monitoring data (2007–2010), hydrogeochemical sampling, and thermal area infra red (IR) survey data are also discussed.