Love-wave propagation in a three-dimensional sedimentary basin

Toshinawa, Takumi; Ohmachi, Tatsuo

doi:10.1785/bssa0820041661

Cited by 45 publications

(4 citation statements)

References 7 publications

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“…the analogy between the travel paths from the major asperities (Wald and Somerville, 1995) and from the 1990 Odawara earthquake. However, modeling the later phases following the direct surface waves using the fiat-layered model proves ineffective and requires a two-or three-dimensional crustal model including the sedimentary basin (e.g., Kudo, 1980;Liu and Heaton, 1984;Vidale and Helmberger, 1988;Yamanaka et aL, 1989Yamanaka et aL, , 1992Toshinawa and Ohmachi, 1992;Kato et aL, 1993;Hisada et al, 1993;Graves, 1993). This problem will be addressed in future work.…”

Section: Estimation Of Source Model By Grid-search Technique Using Bo...mentioning

confidence: 99%

Estimates of regional and local strong motions during the great 1923 Kanto, Japan, earthquake (Ms8.2). Part 1: Source estimation of a calibration event and modeling of wave propagation paths

Sato

Helmberger

Somerville

et al. 1998

Bulletin of the Seismological Society of America

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This article is the first of a pair of articles that estimate regional and local strong motions from the 1923 Kanto, Japan, earthquake. This Ms 8.2 earthquake caused the most devastating damage in the metropolitan area in Tokyo history. In this article, we first calibrate wave propagation path effects with a moderate-sized modern event. This event, the Odawara earthquake of 5 August 1990 (M 5.1), is the first earthquake larger than M 5 in the last 60 years near the hypocenter of the 1923 Kanto earthquake. We estimate the source parameters based on a grid-search technique using body-waveform data bandpass filtered from 1 to 10 sec at four local stations, because accurate source parameters are critical for calibrating the propagation effects. We find that the Odawara earthquake had a depth of 15.3 km, a dip of 35°, a rake of 40°, a strike of 215°, a seismic moment of 3.3 × 1023 dyne-cm, a source duration of 0.65 sec, and a stress drop of 170 bars. Next, we investigate the effects of the propagation paths to the local and regional stations where seismograms of the 1923 Kanto earthquake were recorded, by comparing recorded waveforms with synthetic seismograms built with the calibration event. Path-specific flat-layered velocity models are estimated along travel paths from the event to stations Hongo (epicentral distance R = 82 km) in Tokyo, Gifu (R = 213 km), and Sendai (R = 374 km) using forward modeling. In constructing the velocity model for the Gifu station, we use STS-1 broadband seismograms recorded at the nearby Inuyama station. Consequently, at periods greater than 3 sec, the velocity models for stations Hongo and Gifu can successfully reproduce both body waves and direct surface waves, and the velocity model for Sendai station can explain the predominant direct surface waves. In the companion article (Sato et al., 1998), these velocity models are used to examine the adequecy of the variable-slip rupture models of the 1923 Kanto earthquake (Wald and Somerville, 1995; Takeo and Kanamori, 1992) to explain recorded seismograms and also to simulate strong motions from that event.

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Section: Estimation Of Source Model By Grid-search Technique Using Bo...mentioning

confidence: 99%

Estimates of regional and local strong motions during the great 1923 Kanto, Japan, earthquake (Ms8.2). Part 1: Source estimation of a calibration event and modeling of wave propagation paths

Sato

Helmberger

Somerville

et al. 1998

Bulletin of the Seismological Society of America

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show abstract

“…Horike et al (1990) compared the differences in the amplification effect of ground shaking between 3D and 2D basins and found that the 2D model does not represent the magnitude and duration of the ground shaking in the 3D model. Toshinawa and Ohmachi (1992) used a 3D finite element method to simulate the propagation of Love waves in the Kanto Basin, Japan. They determined that the 3D model yields a larger amplitude and longer duration of ground shaking than the 2D model, and the simulation results obtained by the 3D model were closer to the observed record than those obtained by the 2D model.…”

Section: Introductionmentioning

confidence: 99%

3D seismic simulation analysis of the Longtoushan Town Basin during the 2014 Ludian earthquake, Yunnan province

Liu

et al. 2023

Front. Earth Sci.

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On 3 August 2014, a magnitude Ms 6.5 earthquake struck Ludian County, Zhaotong City, Yunnan Province, causing grave losses of life and property in the Longtoushan Town Basin near the fault. In this study, a three-dimensional model of the Longtoushan Town Basin and the velocity structure of the surrounding area, and the Spectral Elements in Elastic Dynamics code, which combines the discontinuous Galerkin technique and the spectral element method (SEM) are used to simulate and study the entire seismic wave propagation process. The results show that due to the variations in the basin geometry and the impedance ratio of the media inside and outside the basin, the seismic waves incident on the basin edge are refracted and diffracted, further prolonging the ground motion holding time within the basin. In the bedrock outside the basin, the velocity peaks are higher at higher elevations; viceversa within the basin, the locally depressed basement produces an obvious amplification effect. The amplitude of the ground motion is not the greatest in the thickest sedimentary layers in the basin, and it is closely related to the degree of undulation at the base of the sedimentary layers, the overburden thickness, and the basin geometry. The peak ground accelerations (PGAs) of approximately 8 m/s2 in the east–west (E–W) direction and 3 m/s2 in the north–south (N–S) direction are influenced by the rupture directivity effect (the ruptured surface is the Baogunao–Xiaohe fault that is oriented in the N–W direction). The peak ground velocity with a sedimentary model is 2.6 and 1.6 times that of the non-sedimentary model in the E–W and N–S directions, respectively. The maximum amplification factor for PGA in the E–W direction is 2.8 and that in the N–S direction is approximately 2.3. The results are in agreement with the actual observed seismic station data in terms of the waveforms and peaks, and the intensity distribution map matches the actual damage distribution. This proves the accuracy and rationality of the method used in this study. The results are useful for the seismic zoning of cities, and they can help engineers predict ground motions for future large earthquakes.

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“…In the past decades, seismologists have introduced various numerical methods to simulate long-period ground motions (finite element method, discrete wave number method, and spectral element method) (Toshinawa et al 1992;Aoi et al 1999;Komatitsch et al 1999;Graves et al 2008;Takemura et al 2015). Graves et al ( 2008 ) simulated the broadband ground motion of three Mw 7.8 rupture scenarios of the southern San Andreas fault.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Long-period Ground motion: verification and sensitivity study on the 2013 Lushan Mw6.6 earthquake

Chen

et al. 2022

Preprint

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The eastern margin of the Tibetan plateau is adjacent to the Sichuan Basin, which is one of the areas with frequent large earthquakes. The important structures such as bridges and lifeline projects in the region is easily affected by long-period ground motion. It is significant to evaluate the long-period ground motion characteristics of destructive earthquakes in this region. In the first part of this study, the long-period ground motions of the 2013 Lushan Mw6.6 earthquake is simulated using the finite difference method, and three one-dimensional crustal velocity structures are used. We first compared the observed and simulated long-period ground motions of three models in terms of velocity waveforms, pseudo-velocity response spectra, and displacement response spectrum. We then analyzed the residuals of velocity waveforms between the amplitude of simulated and observed. In the second part of this study, the source parameters of rupture velocity, rise time, and stress drop are selected for sensitivity analysis. The results show that it is feasible to use the one-dimensional crustal velocity model of the Sichuan basin to analyze the long-period ground motion of the 2013 Lushan Mw6.6 earthquake. The amplitude of long-period ground motion decreases with the increase of rise time. The amplitude of long-period ground motion and the change of stress drop shows a linear relationship as a whole. The rupture velocity exceeds the shear wave velocity making the PGV distribution of long-period ground motion show spatial variability. In predicting scenario earthquakes, the uncertainty of parameters should be carefully considered. When some parameters are more sensitive to the long-period ground motion, more weights need to be given to these parameters to obtain reliable ground motion results.

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Love-wave propagation in a three-dimensional sedimentary basin

Cited by 45 publications

References 7 publications

Estimates of regional and local strong motions during the great 1923 Kanto, Japan, earthquake (Ms8.2). Part 1: Source estimation of a calibration event and modeling of wave propagation paths

Estimates of regional and local strong motions during the great 1923 Kanto, Japan, earthquake (Ms8.2). Part 1: Source estimation of a calibration event and modeling of wave propagation paths

3D seismic simulation analysis of the Longtoushan Town Basin during the 2014 Ludian earthquake, Yunnan province

Simulation of Long-period Ground motion: verification and sensitivity study on the 2013 Lushan Mw6.6 earthquake

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