The H/V Spectral Ratio Method
Speaker : Cheng Fei-Wen
Abstract
The factors affect the ground motions are quit complex. The main factors are source, path, and local site effects. Spectral ratio analysis is a simple method for studying site effects. The spectral ratio from soil and rock station pair was used to analyze the resonance frequency of the soil layer and the amplification factor in traditionally.
Choosing a perfect rock station in a wide alluvium plain is difficult. If choose a wrong rock station, such as at mountain of the top or valley, it will be affected by the topography. Nakamura (1989) proposed a single station spectral ratio method, using microtremor data to study the resonance frequency of a shallow soil layer.
Using large (CIKS) and small (JSKA) arrays deployed on soft sediments to observe microtremors as well as earthquake motions. Than compared the results of the microtremors and earthquakes by the H/V spectral ratios method.
References
Nakamura, Y. and Dr. Eng. (1989) A Method for Dynamic Characteristics Estimation of Subsurface using Microtremor on the Ground Surface. RTRI, 30 (1)
Horike, M., Zhao, B., Kawase, H. (2001) Comparison of Site Response Characteristics Inferred from Microtremors and Earthquake Shear Waves. Bull. Seism. Soc. Am., 91, 1526-1536