Tomographic Images of Klyuchevskoy Volcano P-Wave Velocity

Three-dimensional structural images of the P-wave velocity below the edifice of the great Klyuchevskoy group of volcanoes in central Kamchatka are derived via tomographic inversion. The structures show a distinct low velocity feature extending from around 20 km depth to 35 km depth, indicating evidence of magma ponding near the Moho discontinuity. The extensive low velocity feature represents, at least to some degree, the source of the large volume of magma currently erupting at the surface near the Klyuchevskoy group

The large Tolbachik fissure eruption in 1975-1976, Kamchatka

International Symposium on the Activity of Oceanic Volcanoes. Ponta Delgada, 4-9 August 1980.This paper discusses the results of seismological, geodetic, geophysical, geologic and petrologic investigations of the large Tolbachik fissure eruption which occurred from July 6, 1975 to Dec. 10, 1976 in Kamchatka. The eruption proceeded first in the region of North vents (July 6-Sept. 15, 1975) where the character of its activity was predominantly explosive and then after a short repose period started again in the region of South vent where its activity was predominantly effusive with outpouring of fluid lava. The total volume of erupted products is 2.3 km³. The time and locality of eruption were successfully predicted according to the character of a swarm of earthquakes recorded at depths from 0 to 20 (30) km. […].info:eu-repo/semantics/publishedVersio

Deep and shallow long-period volcanic seismicity linked by fluid-pressure transfer

International audienceVolcanic long-period earthquakes are attributed to pressure fluctuations that result from unsteady mass transport in the plumbing system of volcanoes. Whereas most of the long-period seismicity is located close to the surface, the volcanic deep long-period earthquakes that occur in the lower crust and uppermost mantle reflect the activity in the deep parts of magmatic systems. Here, we present observations of long-period earthquakes that occurred in 2011-2012 within the Klyuchevskoy volcano group in Kamchatka, Russia. We show two distinct groups of long-period sources: events that occurred just below the active volcanoes, and deep long-period events at depths of ~30 km in the vicinity of a deep magmatic reservoir. We report systematic increases of the long-period seismicity levels prior to volcanic eruptions with the initial activation of the deep long-period sources that reflects pressurization of the deep reservoir and consequent transfer of the activity towards the surface. The relatively fast migration of the long-period activity suggests that a hydraulic connection is maintained between deep and shallow magmatic reservoirs. The reported observations provide evidence for the pre-eruptive reload of the shallow magmatic reservoirs from depth, and suggest that the deep long-period earthquakes could be used as a reliable early precursor of eruptions