Crustal Structure in the Southern Kanto-Tokai Region Derived from Tomographic Method for Seismic Explosion Survey.

Abstract

The detailed P-wave velocity structure of the crust in the southern Kanto-Tokai region was analyzed using the tomographic method for seismic refraction survey in this paper. A total of 332 P-wave arrival times received from 13 seismic explosion surveys were used in the analysis. The results indicate that analyses of travel-time curves are probably useful for the evaluation of inverted structures. The lateral heterogeneity of the velocity structure is obviously related to tectonics. The crust in the eastern region is thinner than that in the western region. The Conrad discontinuity obviously fluctuates.The granitic layer is thinner beneath the oceanic region to the east of Oshima. The layer becomes about 16 km thick beneath Suruga Bay. The Conrad discontinuity drops nearly 17 km in depth beneath Suruga Bay, and velocity is relatively low there. The Conrad discontinuity rises 6 km beneath MTL and its vicinity. The Moho discontinuity is located at a depth of around 34 km beneath the region to the west of ISTL and roughly coincides with the upper boundary of the seismic zone due to subduction of the Philippine Sea Plate under the Eurasian Plate. It becomes shallow across the Suruga trough toward the eastern region. The discontinuity is located about 27 km in depth beneath the oceanic region east of Oshima.

Geometry of slab, intraslab stress field and its tectonic implication in the Nankai trough, Japan

“…4 may be related the flexibility. The tectonic stress field and seismicity in the region east of the Kii peninsula are strongly influenced from the Pacific plate (Zhao et al, 1997). The curved slab geometry of the subducting Philippine Sea plate beneath Shikoku and the Kii peninsula in Fig.…”

Crust and Lithospheric Structure - Active Source Studies of Crust and Lithospheric Structure

“…In practice, shooting methods are more efficient and sufficiently robust for 2-D models, whereas bending methods are favored for 3-D models. Zhao et al (1997) and Chiu et al (1986) applied bending methods to the inversion of 2-D and 3-D wide-angle data.…”

Seismic Traveltime Tomography of the Crust and Lithosphere

“…Chiu et al (1986) use a bending method in the inversion of 3-D reflection traveltimes and Zhao et al (1997) use the pseudo-bending method in the inversion of refraction traveltimes for 2-D crustal structure. In local earthquake tomography, bending methods are probably most commonly used to find source-receiver paths and traveltimes (Eberhart-Phillips, 1990;Scott et al, 1994;Eberhart-Phillips & Reyners, 1997;Graeber & Asch, 1999).…”