2.5-Dmodelling of elastic waves using the pseudospectral method

Furumura, Takashi; Takenaka, Hiroshi

doi:10.1111/j.1365-246x.1996.tb05640.x

Cited by 103 publications

(36 citation statements)

References 32 publications

(27 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To understand the character of the observed recordings during the 1995 Guerrero and the 1999 Oaxaca earthquakes and to examine the influence of the source depth and its type and the structure of the Mexican subduction zone on the features of the seismic-wave field, we conduct 2D numerical simulations using the Fourier spectral method (e.g., Kosloff et al, 1984;Furumura and Takenaka, 1996).…”

Section: D Simulation Of Seismic-wave Propagationmentioning

confidence: 99%

Regional Wave Propagation from Mexican Subduction Zone Earthquakes: The Attenuation Functions for Interplate and Inslab Events

Furumura¹,

Singh²

2002

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

The seismic waves from subduction zone earthquakes are significantly affected by the presence of 3D variation in crust and upper-mantle structure around the source area. These heterogeneous structures also profoundly modify the character of seismic waves as they propagate from the source area to regional distances. This is illustrated by studying shallow, interplate earthquakes along the Mexican subduction zone, and deeper, inslab, normal-faulting earthquakes in the subducted Cocos plate beneath Mexican mainland. The strong-motion recordings of these earthquakes are used to evaluate the character of wave propagation along the path between the source region and Mexico City. We compare the wavefield from two large earthquakes of different source type. During the shallow (H ‫ס‬ 17 km), interplate, 1995 Guerrero earthquake (M w 7.3), the Lg phase is the most prominent feature at regional distances of about 150 to a few hundred kilometers from the source. The presence of a lateral velocity gradient in the crust, caused by the subduction of the Cocos plate, enhances the Lg-wave amplitude, which is then amplified further in the Mexican volcanic belt by amplification in the low-velocity volcanic rocks. Both effects lead to very large ground motions along the path from the coast to the Mexican inland, in the frequency band from 0.2 to 4 Hz. However, for the deeper (H ‫ס‬ 40 km), inslab, normal-faulting, 1999 Oaxaca earthquake (M w 7.5), the amplitude of the Lg phase is too small to produce the abnormal wave propagation, and the direct S wave and its multiple SmS reflections between the free-surface and Moho show a simple attenuation with increasing distance. We compare these observations with numerical simulations of seismic-wave propagation using the Fourier spectral method. The results provide a key to the understanding of seismic-wave field generated by shallow interplate and deeper inslab earthquakes in a realistic 3D heterogeneous structure.

show abstract

Section: D Simulation Of Seismic-wave Propagationmentioning

confidence: 99%

Regional Wave Propagation from Mexican Subduction Zone Earthquakes: The Attenuation Functions for Interplate and Inslab Events

Furumura¹,

Singh²

2002

Bulletin of the Seismological Society of America

View full text Add to dashboard Cite

show abstract

“…Synthetics are compared with observations wherever instrumental data are available, in order to validate and, if needed, to further improve the theoretical techniques. Consequently, during recent years several methods have been proposed for the theoretical estimation of seismic response at a specific site (e.g., FURUMURA and TAKENAKA, 1996;WALD and GRAVES, 1998;FIELD et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

PART I: Theoretical Site Response Estimation for Microzoning Purposes

Triantafyllidis

Suhadolc

Hatzidimitriou

et al. 2004

Pure and Applied Geophysics

View full text Add to dashboard Cite

We estimate the theoretical site response along seven cross sections located in the city of Thessaloniki (Greece). For this purpose the 2-D structural models used are based on the known geometry and the dynamic soil properties derived from borehole measurements and other geophysical techniques. Several double-couple sources have been employed to generate the seismic wavefield, and a hybrid method that combines the modal summation with finite differences, has been deployed to produce synthetic accelerograms to a maximum frequency of 6 Hz for all components of motion. The ratios between the response spectra of signals derived for the 2-D local model and the corresponding spectra of signals derived for the 1-D bedrock reference model at the same site, allow us to estimate the site response due to lateral heterogeneities. We interpret the results in terms of both geological and geometrical features of the models and of the characteristics of the wave propagation. The cases discussed confirm that the geometry and depth of the rock basement, along with the impedance contrast, are responsible for ground amplification phenomena such as edge effects and generation and entrapment of local surface waves. Our analysis also confirms that the peak ground acceleration is not well correlated with damage and that a substantially better estimator for possible damage is the spectral amplification.

show abstract

“…For solving the equations, the numerical modeling scheme by the pseudospectral method (e.g., Kosloff and Baysal, 1982;Kosloff et al, 1984;Furumura et al, 1996) is adopted. In this scheme, the spatial derivatives in Eqs.…”

Section: Methods and Modelsmentioning

confidence: 99%

Effect of vertical velocity gradient on ground motion in a sediment-filled basin due to incident SV wave

2014

Self Cite

View full text Add to dashboard Cite

The natural sedimental deposits in basins show strong vertical heterogeneity in their material parameters. The aim of this paper is to investigate the effects of such vertical heterogeneity, especially vertical velocity gradient, inside basin on the seismic ground motion through the parametric study on the response of a twodimensional semi-cylindrical sediment-filled basin to a vertical incidence of plane SV wave using the pseudospectral method. This numerical study has tried to find the effects caused by vertical velocity gradient through the use of synthetic seismograms, wavefield snapshots and surface amplitude distribution. Simulation results clearly demonstrate the detailed character of wave propagation phenomena in basins with vertical velocity gradient, which produces characteristic amplification pattern of the surface motion caused mainly by the generation of strong Rayleigh wave induced at the basin edge associated with large lateral velocity change across the basin edge. Amplification pattern at the surface strongly depends on both the vertical velocity gradient in the basin and the predominant frequency of the incident wave. Although similar phenomena on wave propagation and surface motion found in previous studies for homogeneous basin models have also been observed in this study, it has been found that the vertical velocity gradient enhances such phenomena. The results suggest that it is important to represent the vertical velocity profiles accurately when we construct a structural model for realistic modelling of ground motion.investigate the phenomena related to the vertical inhomogenity of the sedimental deposit inside basin. Effects of vertical velocity gradient on the wave amplification in sedimentary basin have been studied for several models with different methods mainly for SHwave incidence (Bard and Gariel, 1986;Benites and Aki, 1994). In this paper, the phenomena caused by vertical velocity gradient in a 2D sediment-filled basin is investigated in case of incident SV wave by numerical simulation using the pseudospectral method. Since the SV wave impinging on the material boundaries such as a basin/bedrock interface and the free surface causes strong SV-to-P conversion at the interface and in consequence strong Rayleigh wave is produced at the surface, the ground amplification pattern produced by the SV-wave incidence should be more complicated than that from the SH wave.Numerical studies on the ground motion in sedimentfilled basin have been carried out during last three decades (Takenaka, 1993;Hisada and Yamamoto, 1996). Recent developments in computation technology and the numerical simulation algorithm are making it available to apply 3D simulations of ground motion to realistic structures (e.g., Hisada et al., 1993;Graves, 1998;Furumura et al., 1998). By using realistic 3D models, the effects of various influence factors on ground motion are mixed in a complex manner, which precludes profound understanding of the effect of each factor. For fully understanding the effect of a specific i...

show abstract

2.5-Dmodelling of elastic waves using the pseudospectral method

Cited by 103 publications

References 32 publications

Regional Wave Propagation from Mexican Subduction Zone Earthquakes: The Attenuation Functions for Interplate and Inslab Events

Regional Wave Propagation from Mexican Subduction Zone Earthquakes: The Attenuation Functions for Interplate and Inslab Events

PART I: Theoretical Site Response Estimation for Microzoning Purposes

Effect of vertical velocity gradient on ground motion in a sediment-filled basin due to incident SV wave

Contact Info

Product

Resources

About