Detecting Site Resonant Frequency Using HVSR: FAS vs PSA and f0 vs fp

Session: Near-Surface Effects: Advances in Site Response Estimation and Its Applications [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

In this investigation, we examine the uncertainties using the horizontal-to-vertical spectral ratio (HVSR) technique on earthquake recordings to detect site resonant frequencies at 207 KiK-net sites. Our results show that the scenario-dependence of response (PSA) spectral ratio could bias the estimates of resonant frequencies for sites having multiple significant peaks with comparable amplitudes. Thus, the Fourier spectrum (FAS) should be preferred in computing HVSR. For more than 80% of the investigated sites, the first peak (in the frequency domain) on the average HVSR curve over multiple sites coincides with the highest peak. However, for sites with multiple peaks, the highest peak frequency (f_p) is less susceptible to the selection criteria of significant peaks and the extent of smoothing to spectrum than the first peak frequency (f₀). Meanwhile, comparing to the surface-to-borehole spectral ratio (SBSR), f₀ tends to underestimate the predominant frequency (at which the largest amplification occurs) more than f_p. In addition, in terms of characterizing linear site response, f_p shows a better overall performance than f₀. Based on these findings, we thus recommend seismic network operators to provide f_p on the average HVSR_FAS curve as a priority, ideally together with the average HVSR_FAS curve in site characterization.

Presenting Author: Chuanbin Zhu

Authors