Comparison of three different methods in investigating shallow shear-wave velocity structures in Ilan, Taiwan

Chun Hsiang Kuo, Ding Shing Cheng, Hung Hao Hsieh, Tao Ming Chang, Hsien Jen Chiang, Che Min Lin, Kuo Liang Wen

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The Central Weather Bureau (CWB) and National Center for Research on Earthquake Engineering (NCREE) launched a project to build an engineering geological database for strong-motion stations in Taiwan in 2000. The project measures shear-wave velocity using the suspension PS-logging method. In this study, we conduct array measurements of microtremors and apply the stress wave propagation method (SWPM) at seven free-field strong-motion stations in Ilan County to estimate shallow shear-wave velocity structures. We focus on the sediment layers of the top 100 m to compare the shear-wave velocity structures of the three different methods. There are some misfits among the results of the three different methods; so we calculate the values of Vs30, Vs100 and plot S-wave travel-time curves of these methods for each site to analyze the misfits effectively. This analysis helped us to prove the efficiency of the microtremor array method in investigating shear-wave velocity structures in the shallow subsurface. Moreover, the horizontal-to-vertical ratios of microtremors for each survey point show the existence of divergence at the same site. We considered this as evidence that misfits are caused by the heterogeneous nature of sediments and also due to the nature of the methods as being one-, two- and three-dimensional. Furthermore, the average shear-wave velocity structure of microtremor arrays may be more representative of the whole site.

Original languageEnglish
Pages (from-to)133-143
Number of pages11
JournalSoil Dynamics and Earthquake Engineering
Volume29
Issue number1
DOIs
StatePublished - Jan 2009

Keywords

  • Microtremor array
  • PS-logging
  • Stress wave propagation method (SWPM)

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