Upper Mantle beneath Kamchatka: The Depth Model and Its Relation to Tectonics

The comparative analysis of geological-geophysical data on the deep structure of the Kamchatka Peninsula and the seismic tomography model of the upper mantle revealed the coordinated spatial structure of the regional lithosphere with outlining beneath eastern Kamchatka and the boundaries, thickness, and distribution area of the asthenolith, which was first defined under its central part. Low-velocity bodies connected with the velocity structure of the focal layer and its seismicity patterns are established under recent volcanic belts. It is shown that subordination of the upper mantle structure to fault tectonics is a dominant feature at some of its levels. The system of NW-trending faults in the Petropavlovsk-Kamchatskii area, which is likely responsible for significant horizontal displacements in the upper mantle, is most contrasting. It is assumed that defined asthenolith heterogeneities continue under the Sredinnyi (Median) Range.