ON A SEISMIC CRUSTAL MODEL FOR AVACHA VOLCANO, KAMCHATKA

Abstract

Observations of seismic waves from explosions and earthquakes were used to develop a crustal seismic model beneath Avacha Volcano down to a 2̃0-km depth. Major discontinuities and compressional velocities were determined in the crustal layers. Structural differences were found between the upper and middle crust: steep interfaces and faults, dipping at lower angles further downward, and the variation of elastic and density anomalies. A magma chamber was located at a depth of 12-18 km, and the upper boundary of a peripheral chamber was delineated beneath the volcanic cone. Possible courses for magma migration are indicated.