Research on Characteristics of Present‐Day Crustal Motion and Deformation in Kamchatka Area

Abstract

AbstractWe have collected GPS data in the period of 1995~2005 in Kamchatka, Russia to study the presentday crustal horizontal motion in this area. Strain rate components are computed in a spherical coordinate system. Analyses to the spatial distribution of strain rate fields derived from GPS measurements are carried out in comparison with seismological and geological researches. Results show that microplate boundaries are not clear in the northern Kamchatka peninsula. GPS site velocities in the southern Kamchatka peninsula are generally greater than those in the middle and north of this area. The closer to the eastern subduction zone GPS sites are, the greater their velocities are. The horizontal velocity field obviously exhibits a decrease westward across the peninsula. Generally horizontal motions have the same direction as the Pacific plate subduction zone in this region. All strain rate components are characterized by decreasing westward. The Kamchatka peninsula is undergoing compression in terms of EW and NS strain rate components, with extension in certain local portions. Dilation rates show that the Kamchatka peninsula is under compression. Rigidity rotation rates show that this region is experiencing clockwise motion, especially in the northern zone and southern end. Effective strain rates in the eastern zone are greater than those in the west, and it exhibits a remarkable westward decrease. Principal compression strain rates are apparently greater than principal extension strain rates, especially in the eastern zone. In general, directions of principal compressive strain rates are congruent with horizontal projections of principal compressive axes derived from medium and large earthquakes. The spatial non‐uniform crustal deformation field is associated with the subduction depth, orientation, dipping angle and coupling strength of the boundary interface between the Pacific and North American plates beneath the southeastern Kamchatka peninsula.