Faculty Profiles - TAKENAKA Hiroshi

MISC - TAKENAKA Hiroshi

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Computational methods for seismic wave propagation in complex subsurface structures

TAKENAKA H.

Zisin 46 ( 2 ) 191 - 205 1993

不整形地盤における波動伝播の数値計算法

地震 46 ( 2 ) 191 - 205 1993

Reduction of the memory consumption in the Aki-Larner method(共著)

OHORI Michihiro, TAKENAKA Hiroshi, KOKETSU Kazuki, MINAMI Tadao

Zisin 45 ( 4 ) 357 - 363 1993

Language：Japanese Publisher：SEISMOLOGICAL SOCIETY OF JAPAN

Aki-Larner method (ALM) is a very powerful technique to calculate the seismic responses of layered media having irregular interfaces. However, it is necessary to solve complex simultaneous equations with very large full matrices so that it takes very long time and consume much memory. Recently, Ohminato et al. (1990) proposed a Galerkin method and suggested that wavenumber coupling between far separated elements in the submatrices of the full matrices are very week if the lateral irregurality is gentle. Their idea seems to be applicable to the analyses of ALM, too. Therefore, in this paper, we estimated possible reduction of the memory consumption in the ALM by neglecting most of non-diagonal elements of the submatrices. Through the 2-dimensional (2-D) analyses, we calculated responses due to vertically incident plane SH-wave and studied the effect of the neglect of non-diagonal submatrix elements on the accuracy of results. Six types of alluvial valleys with different shape were used and the error caused by the neglect was evaluated in comparison with results obtained by the conventional ALM. As a result, we can treat submatrices as band matrices with 1/4 or 1/6 width if the lateral irregularity is gentle, and this leads to reduction of the memory consumption in the Aki-Larner method for the simulation in high frequencies or 3-D problems.

DOI： 10.4294/zisin1948.45.4_357

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高速ハートレ変換は高速フーリエ変換を越えるか?（共著）

日本応用数理学会論文誌 3 ( 3 ) 245 - 255 1993

A Field Survey of Tsunami Generated by the Hokkaido-Nansei-Oki Earthquake. From Otaru to Rebun Island.

後藤章夫, 高橋浩晃, 宇津木充, 小野忍, 西田泰典, 大島弘光, 笠原稔, 竹中博士, 斉田智治

日本地震学会秋季大会講演予稿集 1993 1993

Visualization of reciprocity by using a numerical simulation method.

古村孝志, 竹中博士

日本地震学会秋季大会講演予稿集 1993 1993

Calculation of three-dimentional elastic wave field in two dimensional structure using BEM.

藤原広行, 竹中博士

日本地震学会秋季大会講演予稿集 1993 1993

Near-field Observation of Small Earthquakcs Occurring in the Dome of Unzen Volcano

Goto Susumu, Suzuki Sadaomi, Takenaka Hiroshi, Shimizu Hiroshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN 1993 63 - 63 1993

端に不連続を持つデータのためのFourier微分法-対称法-(共著)

FURUMURA T.

物理探査 45 ( 4 ) 303 - 309 1992

Numerical simulation and visualization of seismic wavefield(共著)

FURUMURA T.

Rep. Cent. Infor. Process. Educ., Center for Information Processing Education, Hokkaido Univ. 11 ( 11 ) 25 - 34 1992

地震動の数値シミュレーションの波動場の可視化（共著）

北海道大学情報処理教育センター広報 ( 11 ) 25 - 34 1992

Effect of 2-D Mountain Topography on the 3-D Seismic Wavefield : Isotropic P-wave Source

Takenaka H., Kennett B. L. N.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN 1992 35 - 35 1992

2-D REFLECTIVITY METHOD AND SYNTHETIC SEISMOGRAMS FOR IRREGULARLY LAYERED STRUCTURES .2. INVARIANT EMBEDDING APPROACH

K KOKETSU, BLN KENNETT, H TAKENAKA

GEOPHYSICAL JOURNAL INTERNATIONAL 105 ( 1 ) 119 - 130 1991.4

Language：English Publisher：BLACKWELL SCIENCE LTD

Laterally varying interfaces cause coupling between wavenumbers so that seismograms in two-dimensionally layered media can be synthesized by means of 'supermatrices', which include the coupled contributions of all the wavenumbers. We introduce reflection and transmission 'supermatrices' in order to eliminate numerical problems arising from loss of precision for evanescent waves in the seismogram synthesis. An interface is assumed to be such that the reflected and transmitted wavefields on its two sides can be represented as purely upgoing and downgoing waves, i.e. the Rayleigh ansatz is imposed. The computational demands of this method can be kept to a minimum by exploiting propagation invariants in the coupled wavenumber domain.
The superior performance of this 'invariant embedding' approach when compared to propagator or finite difference schemes is illustrated by application to the response of sedimentary basins to excitation by an incident plane wave or a line force. The results are in good general agreement with the other methods, but show greater numberical stability and computational efficiency. In the case of a single interface the 'invariant embedding' procedure for P-SV-waves takes 45 per cent less computation time and 29 per cent less memory than the propagator method of Koketsu (1987a, b). The gains are reduced in a multilayer case because of the level of computation required to calculate the addition rules for the large reflection and transmission supermatrices.

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2-D REFLECTIVITY METHOD AND SYNTHETIC SEISMOGRAMS FOR IRREGULARLY LAYERED STRUCTURES .2. INVARIANT EMBEDDING APPROACH

K KOKETSU, BLN KENNETT, H TAKENAKA

GEOPHYSICAL JOURNAL INTERNATIONAL 105 ( 1 ) 119 - 130 1991.4

Language：English Publisher：BLACKWELL SCIENCE LTD

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均質な堆積盆地における地震波動場の最も単純な計算法

竹中博士

地震学会講演予稿集 173 1991