Mantle and crustal sources of magmatic activity of Klyuchevskoy and
surrounding volcanoes in Kamchatka inferred from earthquake tomography
Abstract
Klyuchevskoy and surrounding volcanoes in central Kamchatka form the
Northern Group of Volcanoes (NGV), which is an area of the particularly
diverse and intensive Pleistocene-Holocene volcanism. In this study, we
present a new seismic tomographic model of the crust and uppermost
mantle beneath NGV based on local earthquake data recorded by several
permanent and temporary seismic networks including a large-scale KISS
experiment that was conducted in 2015-2016 by an international
scientific consortium. The new model has for Kamchatka an unprecedented
resolution and reveals many features associated with the present and
past volcanic activity within the NGV. In the upper crust, we found
several prominent high-velocity anomalies interpreted as traces of large
basaltic shield volcanoes, which were hidden by more recent volcanic
structures and sediments. For the mantle structures, we found that the
entire system of NGV was fed by an asthenospheric flow arriving through
a slab window located below the Kamchatka-Aleutian junction. The
interaction of the hot asthenospheric material with fluids released from
the slab determines the particular volcanic activity within the NVG. We
argue that the eastern branch of the Central Kamchatka Depression, which
is associated with a prominent low-velocity anomaly in the uppermost
mantle, was formed as a recent rift zone separating the NGV from the
Kamchatka Eastern Ranges.