Investigation of shallow S-wave velocity structure and site response parameters in Taiwan by using high-density microtremor measurements

Chen, Chun‐Te; Kuo, C.-C. Jay; Lin, Ching-Yang; Huang, Jyun‐Yan; Wen, Kuo‐Liang

doi:10.1016/j.enggeo.2021.106498

Cited by 8 publications

(3 citation statements)

References 51 publications

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“…The most popular techniques among various array signal analysis tools are frequency–wavenumber (F-K) and spatially autocorrelation (SPAC) (Hayashi et al, 2022). Here, we opted conventional frequency–wavenumber (CVFK) method (Bozdağ and Kocaoğlu, 2005; Chen et al, 2022; Foti et al, 2018; Lacoss et al, 1969) to extract the best dispersion curve from generated microtremor array data set. At the initial stage of array signal processing, we made attempts for the SPAC method to make a comparison with the CVFK method over extracted dispersion curves.…”

Section: Methodology and Data Analysismentioning

confidence: 99%

Site response analysis beneath the Kashmir basin (NW Himalaya) using ambient noise

Gupta,

Parvez,

Khan

2023

Earthquake Spectra

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Deep sedimentary valleys entrap and amplify seismic waves, which is further responsible for site-specific amplification over the allied region. Kashmir valley is a deep and active sedimentary basin in the northwest portion of the Himalayan lap. To characterize the site response for the intermountain Kashmir valley for the first time, we acquire single station microtremor measurements using Lennartz (three components/5s seismometer) at 141 sites with a grid of (5 km × 5 km) and two-dimensional (2D) array measurements using seven units of recording station of different geometry pattern at 38 sites across different lithological setup within the basin. We present here (1) a first-order predominant fundamental frequency (0.21–10.19 Hz) and subsequent sedimentary thickness maps for the entire valley, reflecting deep deposition with spatial heterogeneity in the area using the horizontal-to-vertical spectral ratio (HVSR) technique; (2) spatial classification of generated HVSR curves linking subsurface geomorphology and post strong ground-motion scenario in the valley; (3) extraction of the best dispersion characteristics of Rayleigh waves (fundamental mode) from all recorded vertical signals at each array site using frequency–wavenumber (F-K) method with an emphasis on signal synchronicity; and (4) retrieval of one-dimensional (1D) shear wave velocity ( VS) profiles across the valley from the inversion of dispersion curves using the neighborhood algorithm. Distinct model parameterizations were tested for the inversion to achieve the optimal inversion misfit. The collocated 1D VS profiles are consistent with newly drilled borehole logs information. Besides, the presented first-ever ambient noise survey–based site response study meets the objectives of site-specific seismic hazard and risk analysis of the Kashmir valley at the regional scale.

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Section: Methodology and Data Analysismentioning

confidence: 99%

Site response analysis beneath the Kashmir basin (NW Himalaya) using ambient noise

Gupta,

Parvez,

Khan

2023

Earthquake Spectra

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“…Other details about how to derive the coefficients of the nonergodic site term were discussed in Chao et al 18 While implementing this approach, it was necessary to have a large number of strong motion instruments near the target site with predicted station terms as well as their MHVRs. Nevertheless, the limitation in Taiwan is that the existing dense MHVRs 38,39 used in GMPE construction 18 are not exactly collocated with the strong motion instruments and the spatial distribution of these MHVRs is not equally distributed. To implement MHVRs to predict the site effect, in this work, several extra microtremors are used from tri-axial acceleration waveforms of twenty minutes for 254 Taiwan Strong Motion Instrumentation Program (TSMIP 40 ) stations directly from the new Taiwan Seismological and Geophysical Data Management System (GDMS-2020, https://gdmsn.cwb.gov.tw) operated by the Central Weather Bureau (CWB).…”

Section: Empirical Site Response Analysismentioning

confidence: 99%

Site‐specific response spectra developed by considering near‐fault motion with finite‐fault simulation in Taiwan

Huang,

Chao,

Lin

et al. 2023

Earthq Engng Struct Dyn

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A new methodology is proposed for developing a scenario‐based site‐specific response spectrum (RS) considering near‐fault effects in Taiwan. First, source parameters, together with reference rock site conditions, are defined according to the available geological and geophysical information at a target site close to a potential active fault in northern Taiwan. Secondly, the scenario‐based response spectrum for a reference rock site condition is developed theoretically through an empirical approach by using a ground motion prediction equation (GMPE). The effect of the pulse period and the occurrence probability of near‐fault pulse‐like ground motion on RS is evaluated by using the ground motion simulation (GMS) technique, in which the stochastic finite‐fault simulation method is validated and applied for evaluating velocity pulse. Third, site‐specific site amplification is incorporated into RS through a site transfer function calculated from the measured horizontal‐to‐vertical Fourier spectral ratio through the microtremor (MHVR) of the target site. Finally, the design spectrum of the target site is compared with the derived site‐specific RS to evaluate the impact of the neighbor fault on the structure of the target site.

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“…This condition is more hazardous because the surface appears safe, but the depth of the sliding plane is a zone that can cause movement in the upper soil layers if the compact rock layer is disturbed. Information about the subsurface structure regarding seismic wave velocity distribution is crucial for understanding soil movement characteristics caused by earthquakes [15]. This research uses the microtremor method to map the soil condition potentially prone to movement or landslides based on the observed soil vulnerability index.…”

Section: Introductionmentioning

confidence: 99%

Vulnerability Index Assessment for Mapping Ground Movements Using the Microtremor Method as Geological Hazard Mitigation

Susilo,

Zulaikah,

Pohan

et al. 2024

Civ Eng J

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Various geological disasters, such as landslides and ground movements, occur annually in Srimulyo Village, Malang District, with varying levels of damage. Ground movements can affect structures built above, causing sinking, cracking, and collapse. Research into landslides and ground movements triggered by vibrations is generally conducted using the microtremor method, which has proven effective. This study uses the microtremor method to map the soil condition that is potentially prone to movement or landslides based on the observed soil vulnerability index. Data was collected using a TDL 303s Digital Portable Seismograph instrument; the measurement points were established in the form of a grid distributed across the research area, with a recording duration of approximately 45 minutes at each point. The analysis technique utilizes the Horizontal Vertical Spectrum Ratio (HVSR) based on the Fast Fourier Transform (FFT) principle. The study’s results found that the research location’s seismic vulnerability index varies between 6.5 and 16.5. Areas with high seismic vulnerability index values, specifically those with Kg>11.5, are scattered on the west, south, and southeast sides of the research location. Based on field observations, these areas are dominated by relatively thick sediment layers, leading to lower dominant frequency values and higher amplification values; consequently, the seismic vulnerability index in the southern region is also high. Doi: 10.28991/CEJ-2024-010-05-017 Full Text: PDF

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Investigation of shallow S-wave velocity structure and site response parameters in Taiwan by using high-density microtremor measurements

Cited by 8 publications

References 51 publications

Site response analysis beneath the Kashmir basin (NW Himalaya) using ambient noise

Site response analysis beneath the Kashmir basin (NW Himalaya) using ambient noise

Site‐specific response spectra developed by considering near‐fault motion with finite‐fault simulation in Taiwan

Vulnerability Index Assessment for Mapping Ground Movements Using the Microtremor Method as Geological Hazard Mitigation

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