Earth Planets Space, Vol. 61 (No. 3), pp. e5-e8, 2009E-LETTER
Azusa Nishizawa, Kentaro Kaneda, Naoko Watanabe, and Mitsuhiro Oikawa
Hydrographic and Oceanographic Department, Japan Coast Guard, Tokyo 104-0045, Japan
(Received September 30, 2008; Revised January 23, 2009; Accepted January 26, 2009; Online published February 23, 2009)
We present detailed P-wave velocity models of subducting seamounts from two wide-angle seismic experiments across the Erimo Seamount and Daiichi-Kashima Seamount, northern and southern ends of the Japan Trench. Common characteristics of the velocity models of the seamounts are that the maximum crustal thicknesses of the seamounts are 12-17 km thicker than a typical oceanic crust and that Pn velocities beneath the seamounts are approximately 7.7 km/s, i.e., slower then those of the neighboring area. These features are very similar to the crustal models for the seamounts produced by the Cretaceous off-ridge volcanism on the Pacific Basin.
Key words: Erimo Seamount, Daiichi-Kashima Seamount, seamount subduction, seismic structure, ocean bottom seismograph.