特別セミナー
日時:2009年4月3日(金)13:30-
場所:環境総合館 講義室1
講演者:Prof. Jonathan M. Lees
     (Department of Geological Sciences, University of North Carolina, Chapel Hill)
講演タイトル:"The Kamchatka-Aleutian Collision Zone: Mother of all Cusps"






講師紹介(セミナー主催者:地震火山・防災研究センター助教 中道治久)

Jonathan Lees教授は2009年2月中旬より東北大学の固体地球物理学講座に客員教授として滞在されております.来日中に今回の講演をお願いいたしました.

講演要旨:
 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.


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