Three-Dimensional P and S Wave Velocity Structure in the Focal Region of the 1984 Western Nagano Prefecture Earthquake
Three-Dimensional P and S Wave Velocity Structure in the Focal Region of the 1984 Western Nagano Prefecture Earthquake
复制标题
1984年长野县西部地震震源区三维纵横波速度结构
DOI：
10.4294/jpe1952.40.343
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
M. Yokohama
中科院分区：
文献类型：
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作者：
K. Hirahara;N. Hirata;A. Ikami;H. Miyamachi;T. Yabuki;H. Aoki;Iwao Fujii;T. Haneda;A. Hasegawa;S. Hashimoto;Norio Hirano;S. Horiuchi;Y. Iio;Yukio Ishiketa;A. Ito;K. Ito;T. Kanazawa;S. Kaneshima;I. Karakama;Masaru Kobayashi;M. Koizumi;T. Kono;M. Kosuga;Y. Kurata;Satoru Kuriyama;A. Kuroiso;T. Matsuzawa;T. Mikumo;Toshio Mitsunami;K. Miura;K. Miura;R. Miyajima;M. Mizoue;T. Moriya;A. Nakajima;Isao Nakamura;Masaru Nakamura;Toru M Nakamura;K. Nishigami;K. Oike;T. Okamoto;T. Okura;Tooru Ooida;T. Ouchi;T. Saeki;K. Sakai;T. Shibutani;Masayuki Suzuki;Sadaomi Suzuki;Masayoshi Takahashi;A. Takagi;F. Takeuchi;T. Tanada;Shoji Tomita;T. Tsukuda;Y. Umeda;H. Wada;M. Yamada;A. Yamamoto;K. Yamashina;F. Yamazaki;M. Yokohama
1984 年长野县西部地震发生在日本中部御岳山活火山附近，震源区的详细三维 P 和 S 波速度结构源自 1986 年长野县西部联合地震研究获得的走时数据的层析反演。该数据集包括 49 个台站观测到的 212 次当地地震和 2 次爆炸的 7, 693 个 P 波和 6, 070 个 S 波到达时间。上地壳浅层的速度在每个网格点上测定，网格点的间距为1-2公里，从地球表面到4公里的深度都获得了良好的分辨率。特别是从地表到1km深度存在较强的横向非均质性。海拔1 km高度井测得的地震速度图与地表地质及布格重力异常图相对应。然而，这种对应关系在更深层次上并不那么清楚。而且，深度越大，速度结构的异质性就越少。断层上的速度分布似乎与通过强运动和大地测量数据分析估计的位错和破裂前缘的分布相对应：低速区域有大量的位错和延迟的破裂前缘。
The detailed three-dimensional P and S wave velocity structure in the focal region of the 1984 Western Nagano Prefecture Earthquake occurring close to an active volcano, Mt. Ontake, central Japan, is derived from a tomographic inversion of travel time data obtained by the 1986 Joint Seismological Research in Western Nagano Prefecture. The data set includes 7, 693 P-wave and 6, 070 S-wave arrival times observed at 49 stations from 212 local earthquakes and 2 explosions. The velocities in the shallow portion of upper crust are determined at each grid point with its spacing of 1-2 km and good resolutions are obtained from the Earth's surface to a depth of 4 km. There exist strong lateral heterogeneities especially from the surface to a depth of 1 km. The seismic velocity map obtained in the height of 1 km above sea level well corresponds to the maps of surface geology and Bouguer gravity anomaly. This correspondence, however, is not so clear in the deeper layers. And, the greater the depth, the less heterogeneous the velocity structure. The velocity distribution on the fault seems to correspond to the distribution of dislocation and rupture front estimated from an analysis of strong motion and geodetic data: the low velocity region has the large amount of dislocation and the retarded rupture front.