Simultaneous determination of the three-dimensional crustal structure and hypocenters beneath the Kanto—Tokai District, Japan

Ashiya, Kimitoshi; Asano, Shûzô; Yoshii, Toshikatsu; Ishida, M.; Nishiki, Tsukasa

doi:10.1016/0040-1951(87)90137-5

Cited by 38 publications

(12 citation statements)

References 11 publications

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“…An example of the former is an expansion in a set of continuous, orthogonal basis functions (e.g., sinusoidal or spherical harmonic functions) where the spatial resolution is limited by the number of terms included in the expansion (Novotny, 1981). Examples of the latter are the subducting slab parameterization of Spencer and Gubbins (1980), in which the slab is represented by its strike, dip, width, slowness contrast, and decay rate with depth; the fault zone parameterization of Wesson (1971), in which the fault zone is represented by its velocity decrease, decay with depth and distance, and the velocity contrast across it; and the quasilayered parameterization of Ashiya et al (1987) employing a sum of hyperbolic tangent functions for the depth variation of velocity and Chebyshev functions for the lateral variation of velocity.…”

Section: Cells Nodes and Basis Functionsmentioning

confidence: 99%

Theory and Observations - Seismic Tomography and Inverse Methods

Thurber

Ritsema

2015

Treatise on Geophysics

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Section: Cells Nodes and Basis Functionsmentioning

confidence: 99%

Theory and Observations - Seismic Tomography and Inverse Methods

Thurber

Ritsema

2015

Treatise on Geophysics

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“…In the last two decades, progress in seismic observation networks provided high-quality arrival-time data of P and S waves and made it possible to estimate the fine structure of the seismic wave velocities in the earth. Moreover, the high-quality seismological data stimulated the development of new techniques for retrieving the crustal structure (e.g., HORIUCHI et al, 1982a;ASHIYA et al, 1987;ZHAO et al, 1992a). In particular, HORIUCHI et al (1982a) contrived a method to determine both locations of earthquake hypocenters and two-dimensional variations of the depths to the Conrad and Moho discontinuities from the P-and S-wave travel-time data from local earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Topography of the Seismic Velocity Discontinuities beneath the Chugoku and Shikoku Districts, Southwest Japan

Oda

Okamoto

Ishise

2005

Pure appl. geophys.

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The first P-arrival-time data from 513 local earthquakes were analyzed to study lateral variation of the depth to the Conrad and Moho discontinuities beneath the Chugoku and Shikoku districts, southwest Japan, as well as to determine earthquake hypocenters and P-wave station corrections. The depth to the discontinuity was estimated by minimizing the travel-time residuals of more than 8700 first P arrivals observed at 55 seismic stations. The Conrad and Moho discontinuities are located within depth ranges of 15-25 km and 30-40 km, respectively. The Moho is deeper under the mountain area than under the Seto Inland Sea area, and especially deep under the Pacific Coast of the Shikoku district and the mountain area in the Chugoku district. The depth variation of the Moho is quite similar to the Bouguer gravity anomaly distribution and the lateral variations of the P-wave velocity. The deep Moho under the southern Shikoku is located at the portion in which the continental Moho under the island arc meets the oceanic Moho that is the boundary interface between the oceanic crust and the Philippine Sea (PHS) plate dipping toward the back arc. Although there are high mountains in the northern and middle Shikoku, the Moho is not so deep because subduction of the PHS plate prevents the Moho from getting deep, while the Moho is deep due to isostatic balance under the mountain area in the Chugoku district. In addition, we indicated the possibility that the upper boundary of the oceanic crust just above the high-velocity PHS plate is in contact with the deep Moho under the western Chugoku. The contact of the Moho with the oceanic crust can explain the markedly negative gravity anomaly observed in the western Chugoku and the later phase that appears just after the first P arrival from local earthquakes.

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“…Miyamachi and Moriya, 1984;Nakanishi, 1985;Hasemi et al, 1984;Obara et al, 1986;Sato et al, 1989;Zhao, 1991;Zhao et al, 1992;Zhao and Hasegawa, 1993). The methods for modeling the 3-D velocity structure used in these studies are basically classified into two: one is a discrete method represented by the "block configuration" of Aki and Lee (1976) or the "grid configuration" of Thurber (1983), and the other is the functional method using some continuous functions (Horiuchi et al, 1982;Ashiya et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the functional method uses some continuous functions such as power series (Horiuchi et al, 1982;Sato, 1981) and Chebyshev's function (Ashiya et al, 1987) to describe the depth distributions of the boundaries or the 3-D velocity distribution. In general, the number of unknown parameters in the functional method is less than that in the discrete method.…”

Section: Introductionmentioning

confidence: 99%

A Method for Determination of the Three-Dimensional Seismic Velocity Structure from Local Earthquake Data.

Miyamachi

1994

J,Phys,Earth

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We have developed an inverse method to estimate a three-dimensional seismic wave velocity structure using seismic arrival time data obtained from local earthquakes. The method is characterized by a simultaneous determination of a two-dimensional depth distribution of a velocity boundary, a three-dimensional velocity distribution, station corrections and hypocenters. The depth distributions of velocity boundaries and the distributions of the slowness perturbations for P and S waves are modeled by power series of latitude, longitude, and depth, This representation of the three-dimensional seismic structure is advantageous not only in reducing the number of unknown parameters, but also in analytically evaluating the boundary depths, velocities, and partial derivatives of travel times with respect to the unknown parameters. Ray trajectories connected between hypocenters and stations are determined by the so-called shooting method for ray tracing scheme under a simplified velocity distribution with the exact boundary depth distribution. Numerical experiments have proved that our inverse method can successfully estimate the three-dimensional velocity structure.

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Simultaneous determination of the three-dimensional crustal structure and hypocenters beneath the Kanto—Tokai District, Japan

Cited by 38 publications

References 11 publications

Theory and Observations - Seismic Tomography and Inverse Methods

Theory and Observations - Seismic Tomography and Inverse Methods

Topography of the Seismic Velocity Discontinuities beneath the Chugoku and Shikoku Districts, Southwest Japan

A Method for Determination of the Three-Dimensional Seismic Velocity Structure from Local Earthquake Data.

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