Seismic tomography of the Pacific slab edge under Kamchatka

摘要: Abstract We determine a 3-D P-wave velocity structure of the mantle down to 700 km depth under Kamchatka peninsula using 678 arrival times collected from digital seismograms 75 teleseismic events recorded by 15 portable seismic stations and 1 permanent station in Kamchatka. The subducting Pacific slab is imaged clearly that visible upper extends below 660-km discontinuity southern Kamchatka, while it shortens toward north terminates near Aleutian–Kamchatka junction. Low-velocity anomalies are beneath northern junction, which interpreted as asthenospheric flow. A gap model without remnant fragment proposed interpret main feature high-V anomalies. Combining our tomographic results with other geological geophysical evidences, we consider loss may be induced friction surrounding asthenosphere plate rotated clockwise at about 30 Ma ago, then was enlarged slab-edge pinch-off flow presence Meiji seamounts. As result, subducted seamounts have jointly caused subduct lower dip angle made Sheveluch Klyuchevskoy volcanoes shift westward.