Publication Date:
2013-03-22
Description:
This paper uses microtremor-array measurements to obtain an overall view of S -wave velocity structure in the Chiayi area, Taiwan. The Rayleigh-wave dispersion curves are calculated using the frequency-wavenumber ( ) spectrum method and then the S -wave velocity structure of the area is estimated by surface-wave inversion. According to the inversion results, the S -wave velocities decrease from east to west. If the S -wave velocity of the bedrock is assumed to be 1500 m/s, the depths of the alluvium are between 560 and 1400 m gradually increasing from east to west. In order to understand the variations of the shallow S -wave velocity in the area, we sketch 2D and 3D maps using the imaging techniques based on interpolation algorithms. From the 3D results, the thickness of the sediments having an S -wave velocity in the range 270–1500 m/s increases from east to west; whereas the thickness of the layers having an S -wave velocity in the range 1500–2370 m/s decreases from east to west. The results are also in good agreement with the geological and geophysical information of the Chiayi area. Therefore, microtremor-array measurement provides a good alternate to estimate shallow S -wave velocity structure. Online Material: Figures showing observed and calculated phase velocities, f - k spectra, dispersion curves, inverted velocity models, sensitivity kernels, and V S contour maps and electric resistivity maps.
Print ISSN:
0037-1106
Electronic ISSN:
1943-3573
Topics:
Geosciences
,
Physics
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