One of the most important findings is a feature below 25 km depth
with extremely high Vp/Vs ratio reaching 2.2. This feature with
higher P- and very low S-velocities is probably an image of the top
part of a mantle channel which brings deep mantle material with high
fluid and melt content. This mantle “finger” appears to be directly or
indirectly responsible for all volcanic activity in the Kluchevskoy group