AVACHA DEPRESSION, KAMCHATKA: STRUCTURE OF THE BASEMENT

Abstract

The structure of the avacha Depression, covered by a thick sequence of volcanic rocks, volcano-sedimentary deposits, and loose Quaternary sediments of varying origins, was reconstructed using the results of a geological survey, geophysical measurements, and drilling data. The depression had a long tectonic history related to a complex combination of linear faults and ring volcano-tectonic faults that obviously controlled the localization of the Avacha-Koryak group of volcanoes. The structure and origin of the Ketka geothermal field, discovered in the SW side of the depression, are discussed.