Japan Geoscience Union Meeting 2015

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International Session (Oral)

Symbol S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT03] Structure and dynamics of Earth and Planetary deep interiors

Mon. May 25, 2015 2:15 PM - 4:00 PM 106 (1F)

Convener:*Takashi Yoshino(Institute for Study of the Earth's Interior, Okayama University), Satoru Tanaka(Department of Deep Earth Structure and Dynamics Research Japan Agency for Marine-Earth Science and Technology), Dapeng Zhao(Department of Geophysics, Tohoku University), Masanori Kameyama(Geodynamics Research Center, Ehime University), John Hernlund(Earth-Life Science Institute, Tokyo Institute of Technology), Chair:Dapeng Zhao(Department of Geophysics, Tohoku University), Konstantin Litasov(V.S. Sobolev Institute of Geology and Mineralogy SB RAS)

3:15 PM - 3:30 PM

[SIT03-05] Thickness of the mantle transition zone beneath the Society hotspot

*Daisuke SUETSUGU1, Hiroko SUGIOKA1, Takehi ISSE2, Aki ITO1, Hajime SHIOBARA2 (1.Japan Agency for Marine-Earth Science and Technology, 2.Earthquake Research Institute, the University of Tokyo)

Keywords:hotspot, ocean bottom seismograph, receiver function, French Polynesia

We have conducted a seafloor geophysical observation from 2009 to 2010 near
the Society hotspot. The observation network was composed of nine sets of
broadband seismographs and electro-magnetometers, and two differential pressure gauges. In this presentation we show the mantle transition zone (MTZ) structure obtained with a receiver function method using the broadband seismograms. We employed a common-conversion point (CCP) stacking technique to map the MTZ thickness. A preliminary result indicates an area of a thin MTZ 200 km to the south of the Society hotspot (thinner than global average by 20-30 km). The lateral dimension of the thin MTZ area is about 200 km. There is another area of the thin MTZ 300 km EES to the hotspot. The thin MTZ areas are roughly correlated with slow P-velocities in the MTZ in the P-wave tomograms (Obayashi et al., 2014). They may represent hot mantle plumes ascending from the lower mantle.