Derivation of consistent hard rock (1000 < VS < 3000 m/s) GMPEs from surface and down-hole recordings: analysis of KiK-net data

Abstract

A key component in seismic hazard assessment is the estimation of ground motion for hard rock sites, either for applications to installations built on this site category, or as an input motion for site response computation. Empirical ground motion prediction equations (GMPEs) are the traditional basis for estimating ground motion while V S30 is the basis to account for site conditions. As current GMPEs are poorly constrained for V S30 larger than 1000 m/s, the presently used approach for estimating hazard on hard rock sites consists of ''host-to-target'' adjustment techniques based on V S30 and j 0 values. The present study investigates alternative methods on the basis of a KiK-net dataset corresponding to stiff and rocky sites with 500 \ V S30 \ 1350 m/s. The existence of sensor pairs (one at the surface and one in depth) and the availability of P-and S-wave velocity profiles allow deriving two ''virtual'' datasets associated to outcropping hard rock sites with V S in the range [1000, 3000] m/s with two independent corrections: 1/down-hole recordings modified from withinThe following softwares are employed in this study: 1) the one written by J.-C. Gariel and P.-Y.Bard of the 1D reflectivity approach (Kennett 1974); 2) the site_amp v.5.6 program package provided by Dave Boore (U.S. Geological Survey); and the pikwin software developed by Perron et al. (2017). DOI 10.1007/s10518-017-0142-6 motion to outcropping motion with a depth correction factor, 2/surface recordings deconvolved from their specific site response derived through 1D simulation. GMPEs with simple functional forms are then developed, including a V S30 site term. They lead to consistent and robust hard-rock motion estimates, which prove to be significantly lower than host-to-target adjustment predictions. The difference can reach a factor up to 3-4 beyond 5 Hz for very hard-rock, but decreases for decreasing frequency until vanishing below 2 Hz. Electronic supplementary materialBull Earthquake Eng

Integration of Site Effects into Probabilistic Seismic Hazard Assessment (PSHA): A Comparison between Two Fully Probabilistic Methods on the Euroseistest Site

“…For the sake of simplicity in the present exercise, the hazard curve has been derived with only one GMPE (Akkar et al, 2014) (AA14) [36], which is satisfactorily representative of the median hazard curve on rock obtained with seven other GMPEs deemed to be relevant for the European area (see [15]). The host-to-target (HTT) adjustments have been performed here on the basis of simple velocity adjustments calibrated on KiKnet data using the Laurendeau et al, 2107 GMPE [37], since the detailed knowledge of the site characteristics does not compensate the very poor information on the "host" characteristics of any GMPE (in particular those from European data), which results in very large uncertainty levels in classical HTT approaches [38].…”

“…It is therefore mandatory to perform what is known in literature as "host-to-target adjustment" corrections (HTT [31][32][33][34]). As discussed in [14,15], the high level of complexity and uncertainty associated to the current HTT adjustments procedures [16,37,[49][50][51], have motivated us to use here another, simpler, straightforward way to account for rock to hard rock correction for probabilistic seismic hazard purposes.…”

“…This simpler approach is based on the work by Laurendeau et al, 2017 (LA17) [37], who proposed a new rock GMPE that is valid for surface velocities ranging from 500 m/s to 3000 m/s and derived on the basis of the Japanese KiK-net dataset [52]. This GMPE presents the advantage to rely only on the value of rock velocity, without requiring the κ 0 values either for the host region or for the target site, and therefore avoiding the associated uncertainties.…”

“…It may account for the variability of some other mechanical characteristics (such as κ 0 , or the fundamental frequency f 0 ), but only through their potential correlations with V S30 . We consider, as discussed in [37,38], that such an approach is as reliable as the conventional HTT approach due to the huge uncertainties and possible bias linked with the measurement of the physical parameter κ 0 . It provides rather robust predictions of rock motion whatever the approach used for their derivation: deconvolution of surface recordings to outcropping bedrock with the known 1D profile, or the correction of down-hole recordings, see [37] for the corresponding discussion.…”

Main Achievements of the Multidisciplinary SINAPS@ Research Project: Towards an Integrated Approach to Perform Seismic Safety Analysis of Nuclear Facilities

“…State-of-the-art GMPEs require several site-specific parameters, used as 'proxys' in their functional forms. Laurendeau et al (2017) and Bora et al (2015Bora et al ( , 2017 took advantages of the availability of well-characterized strong motion databases (i.e., KikNet, Resorce, respectively) to propose alternative approaches to classical host-to-target corrections, mainly based on the Vs 30m and Kappa parameters. These studies showed that the host-to-target adjustment is particularly 'approach-sensitive', and results might vary widely.…”