S-wave velocity structures of the Taipei Basin, Taiwan, using microtremor array measurements

Huang, Huey Chu; Wu, Cheng Feng; Lee, Feng Mei; Hwang, Ruey Der

doi:10.1016/j.jseaes.2015.01.003

Cited by 8 publications

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References 26 publications

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“…In terms of economical and practical considerations, microtremor array measurements provide a favorable alternative in estimating S-wave velocity structures. Many studies have employed microtremor array measurements to examine material properties [3][4][5][6][7][8][9][10][11][12][13][14]. Singh et al [15] estimated the site characteristics of different geological formations in the Kachchh seismic zone of western India by conducting microtremor array measurements at 7 sites and single-station microtremor measurements at 36 sites.…”

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confidence: 99%

Estimation of Shear-Wave Velocity Structures in Taichung, Taiwan, Using Array Measurements of Microtremors

et al. 2021

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Near-surface S-wave velocity structures (VS) are crucial in site-effect studies and ground-motion simulations or predictions. We explored S-wave velocity structures in Taichung, the second-largest city in Taiwan by population, by employing array measurements of microtremors at a total of 53 sites. First, the fundamental-mode dispersion curves of Rayleigh waves were estimated by adopting the frequency–wavenumber analysis method. Second, the surface-wave inversion technique was used to calculate the S-wave velocity structures of the area. At many sites, observed phase velocities were almost flat, with a phase velocity of approximately 800–1300 m/s in the frequency range of 0.6–2 Hz. A high-velocity zone (VS of 900–1500 m/s) with a convex shape was observed at the shallow S-wave structures of these sites (depths of 50–500 m). On the basis of the inversion results, we constructed two-dimensional and three-dimensional contour maps to elucidate the variations of VS structures in Taichung. According to VS-contour maps at different depths, lowest S-wave velocities are found at the western coastal plain, whereas highest S-wave velocities appear on the eastern side. The S-wave velocity gradually decreases from east to west. Moreover, the S-wave velocity of the Tertiary bedrock is assumed to be 1500 m/s in the area. According to the depth-contour map (VS = 1500 m/s), the depths of the bedrock range from 250 m (the eastern part) to 1550 m (the western part). The thicknesses of the alluvium gradually decrease from west to east. Our results are consistent with the geology of the Taichung area.

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