EXPEDITIONARY RESEARCH ON THE KRONOTSKY PENINSULA

Abstract

The sublatitudinal active fault on the Kronotsky Peninsula (Kamchatka) has been studied. The deformations of the Holocene soil-pyroclastic cover opened by the trench indicate reverse vertical movements along the fault plane. The northern fault side is relatively downthrown. Evidence for a horizontal component is less certain because of the small number of geomorphologic references, but together they indicate that it is left-latetal. The average rate of strike-slip movements can be estimated to be of the order of 10 mm per year. Two explanations for the existence of a arc-normal active fault seem possible: the fault as part of a transform left-lateral horizontal flexure connecting the collisional part of Kamchatka with its transverse extension-prone part, and the fault as a result of clockwise rotation of the Kronotsky Peninsula block. The second option implies that the Pacific plate is being pushed under Kamchatka at an angle to it and seems less likely.