The Kamchatka-Aleutian Collision Zone: Mother of all Cusps

Speaker: Jonathan M. Lees
The Kamchatka subduction zone represents a key to the understanding of volcanism, tectonics and mantle dynamics. The termination of the Pacific plate in the northern part of the Kamchatka slab is the prime location to investigate the cusp-ward shoaling of seismicity, the volumetrically spectacular production of magma with unusual geochemical signatures and slab edge ablation associated with mantle flow around the leading edge of the plate. In addition, the Kamchatka subduction zone is further complicated by the subduction of the aseismic ridge, the Meiji Seamounts. The three-dimensional structural configuration of the subducting pacific slab, the Komandorsky basin and the volcanic arc all suggest that absence of Pacific slab north of latitude. Tomographic analyses show a deep low velocity zone below Kliuchevskoi Volcano, suggesting a deep source near the crust-mantle interface. The intense volcanic production rates of the northern part of the Kamchatka Arc indicate that a prolific source feeds the surface expression of the cusp. Extensive heating at the exposed slab edge provides a source of heat for the Kliuchevskoi group. In this presentation I will review the critical observations and conclusions regarding cusp dynamics in Kamchatka and the Pacific Rim.In the beginning 15 minutes, there will be a video presentation on Santiaguito Volcano Explosion.