TY - JOUR
T1 - Three-dimensional P- and S-wave velocity structures beneath Japan
AU - Nakamura, Masaki
AU - Yoshida, Yasuhiro
AU - Zhao, Dapeng
AU - Takayama, Hiroyuki
AU - Obana, Koichiro
AU - Katao, Hiroshi
AU - Kasahara, Junzo
AU - Kanazawa, Toshihiko
AU - Kodaira, Shuichi
AU - Sato, Toshinori
AU - Shiobara, Hajime
AU - Shinohara, Masanao
AU - Shimamura, Hideki
AU - Takahashi, Narumi
AU - Nakanishi, Ayako
AU - Hino, Ryota
AU - Murai, Yoshio
AU - Mochizuki, Kimihiro
PY - 2008/5/1
Y1 - 2008/5/1
N2 - We determined the three-dimensional Vp and Vs structures beneath Japan by applying seismic tomography to a large number of arrival times recorded at temporary stations in the Japan Sea and the Pacific Ocean, as well as those at permanent stations on the Japan Islands. As a result, we obtained more precise seismic images than previous studies. In the crust and the uppermost mantle, southwestern Honshu exhibited weaker heterogeneity than the other areas in Japan, corresponding to the distribution of active volcanoes. Stripe-like heterogeneities exist in the subducting Pacific slab. Relatively low-velocity zones correspond to low-seismicity areas in the Pacific slab, suggesting that the slab is possibly torn or thin around the areas. The fact that nonvolcanic deep tremors associated with the subducting Philippine Sea slab beneath Shikoku, Kii, and Tokai do not occur in zones of high Vp, high Vs, and low Vp/Vs ratio may reflect the existence of fluids generated by the dehydration processes of the slab. Prominent and wide low Vp and Vs zones exist beneath central Honshu at the depth range of 30-60 km, where the volcanic front related to the subducting Pacific plate is located and seismicity around the Philippine Sea plate is very low. This condition may exist because magma genesis processes related to the subducting Pacific plate activate the same processes around the Philippine Sea plate.
AB - We determined the three-dimensional Vp and Vs structures beneath Japan by applying seismic tomography to a large number of arrival times recorded at temporary stations in the Japan Sea and the Pacific Ocean, as well as those at permanent stations on the Japan Islands. As a result, we obtained more precise seismic images than previous studies. In the crust and the uppermost mantle, southwestern Honshu exhibited weaker heterogeneity than the other areas in Japan, corresponding to the distribution of active volcanoes. Stripe-like heterogeneities exist in the subducting Pacific slab. Relatively low-velocity zones correspond to low-seismicity areas in the Pacific slab, suggesting that the slab is possibly torn or thin around the areas. The fact that nonvolcanic deep tremors associated with the subducting Philippine Sea slab beneath Shikoku, Kii, and Tokai do not occur in zones of high Vp, high Vs, and low Vp/Vs ratio may reflect the existence of fluids generated by the dehydration processes of the slab. Prominent and wide low Vp and Vs zones exist beneath central Honshu at the depth range of 30-60 km, where the volcanic front related to the subducting Pacific plate is located and seismicity around the Philippine Sea plate is very low. This condition may exist because magma genesis processes related to the subducting Pacific plate activate the same processes around the Philippine Sea plate.
KW - Dehydration process
KW - Pacific slab
KW - Philippine Sea slab
KW - Seismic activity
KW - Seismic wave travel time tomography
KW - Volcano
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U2 - 10.1016/j.pepi.2008.04.017
DO - 10.1016/j.pepi.2008.04.017
M3 - Article
AN - SCOPUS:46849084573
VL - 168
SP - 49
EP - 70
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
SN - 0031-9201
IS - 1-2
ER -