Three-dimensional P- and S-wave velocity structures beneath Japan
Three-dimensional P- and S-wave velocity structures beneath Japan
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DOI：
10.1016/j.pepi.2008.04.017
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发表时间：
2008-05-01
影响因子：
2.3
通讯作者：
Mochizuki, Kimihiro
中科院分区：
文献类型：
--
作者：
Nakamura, Masaki;Yoshida, Yasuhiro;Mochizuki, Kimihiro
我们确定了三维Vp和Vs结构下，日本通过地震层析成像记录在日本海和太平洋的临时站，以及在日本群岛上的永久站的大量的到达时间。因此，我们获得了比以前的研究更精确的地震图像。在地壳和上地幔，本州西南部表现出较弱的不均匀性比日本其他地区，对应于活火山的分布。太平洋板块俯冲带存在条带状不均匀性。相对低速区对应于太平洋板块的低地震活动区，这表明该板块可能在该地区周围撕裂或变薄。与四国岛、纪伊岛和东海下菲律宾海板块俯冲相关的非火山性深震没有发生在高Vp、高Vs和低Vp/Vs比值区域，这一事实可能反映了板块脱水过程产生的流体的存在。本州中部30-60 km深度范围内存在着显著而广泛的低Vp和Vs带，这里是与太平洋板块俯冲有关的火山前缘所在地，菲律宾海板块周围的地震活动很低。这种情况可能存在，因为与俯冲太平洋板块有关的岩浆成因过程激活了菲律宾海板块周围的相同过程。2008 Elsevier B. V.保留所有权利。
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. 2008 Elsevier B.V. All rights reserved.