TY  - JOUR
A1  - Zhu, Chuanbin
A1  - Cotton, Fabrice
A1  - Kawase, Hiroshi
A1  - Händel, Annabel
A1  - Pilz, Marco
A1  - Nakano, Kenichi
T1  - How well can we predict earthquake site response so far?
BT  - site-specific approaches
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - Earthquake site responses or site effects are the modifications of surface geology to seismic waves. How well can we predict the site effects (average over many earthquakes) at individual sites so far? To address this question, we tested and compared the effectiveness of different estimation techniques in predicting the outcrop Fourier site responses separated using the general inversion technique (GIT) from recordings. Techniques being evaluated are (a) the empirical correction to the horizontal-to-vertical spectral ratio of earthquakes (c-HVSR), (b) one-dimensional ground response analysis (GRA), and (c) the square-root-impedance (SRI) method (also called the quarter-wavelength approach). Our results show that c-HVSR can capture significantly more site-specific features in site responses than both GRA and SRI in the aggregate, especially at relatively high frequencies. c-HVSR achieves a "good match" in spectral shape at similar to 80%-90% of 145 testing sites, whereas GRA and SRI fail at most sites. GRA and SRI results have a high level of parametric and/or modeling errors which can be constrained, to some extent, by collecting on-site recordings.
KW  - Site response
KW  - site effects
KW  - HVSR
KW  - ground response analysis
KW  - square-root-impedance
KW  - earthquake
Y1  - 2022
U6  - https://doi.org/10.1177/87552930211060859
SN  - 8755-2930
SN  - 1944-8201
VL  - 38
IS  - 2
SP  - 1047
EP  - 1075
PB  - Sage Publ.
CY  - Thousand Oaks
ER  - 
TY  - JOUR
A1  - Zhu, Chuanbin
A1  - Pilz, Marco
A1  - Cotton, Fabrice Pierre
T1  - Evaluation of a novel application of earthquake HVSR in site-specific amplification estimation
JF  - Soil dynamics and earthquake engineering
N2  - Ground response analyses (GRA) model the vertical propagations of SH waves through flat-layered media (1DSH) and are widely carried out to evaluate local site effects in practice. Horizontal-to-vertical spectral ratio (HVSR) technique is a cost-effective approach to extract certain site-specific information, e.g., site fundamental frequency (f(0)), but HVSR values cannot be directly used to approximate the levels of S-wave amplifications. Motivated by the work of Kawase et al. (2019), we propose a procedure to correct earthquake HVSR amplitudes for direct amplification estimations. The empirical correction compensates HVSR by generic vertical amplification spectra categorized by the vertical fundamental frequency (f(0v)) via kappa-means clustering. In this investigation, we evaluate the effectiveness of the corrected HVSR in approximating observed linear amplifications in comparison with 1DSH modellings. We select a total of 90 KiK-net (Kiban Kyoshin network) surface-downhole sites which are found to have no velocity contrasts below their boreholes and thus of which surface-to-borehole spectral ratios (SBSRs) can be taken as their empirical transfer functions (ETFs). 1DSH-based theoretical transfer functions (TTFs) are computed in the linear domain considering uncertainties in Vs profiles through randomizations. Five goodness-of-fit metrics are adopted to gauge the closeness between observed (ETF) and predicted (i.e., TTF and corrected HVSR) amplifications in both amplitude and spectral shape over frequencies from f(0) to 25 Hz. We find that the empirical correction to HVSR is highly effective and achieves a "good match" in both spectral shape and amplitude at the majority of the 90 KiK-net sites, as opposed to less than one-third for the 1DSH modelling. In addition, the empirical correction does not require a velocity model, which GRAs require, and thus has great potentials in seismic hazard assessments.
KW  - site amplification
KW  - HVSR
KW  - ground response analysis
KW  - KiK-net
KW  - earthquake
Y1  - 2020
U6  - https://doi.org/10.1016/j.soildyn.2020.106301
SN  - 0267-7261
SN  - 1879-341X
VL  - 139
PB  - Elsevier
CY  - Oxford
ER  -