Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes

Abstract

We present the regional ground-motion prediction equations for peak ground acceleration (PGA), peak ground velocity (PGV), pseudo-spectral acceleration (PSA), and seismic intensity (MSK scale) for the Vrancea intermediate depth earthquakes (SE-Carpathians) and territory of Romania. The prediction equations were constructed using the stochastic technique on the basis of the regional Fourier amplitude spectrum (FAS) source scaling and attenuation models and the generalised site amplification functions. Values of considered ground motion parameters are given as the functions of earthquake magnitude, depth and epicentral distance. The developed ground-motion models were tested and calibrated using the available data from the large Vrancea earthquakes. We suggest to use the presented equations for the rapid estimation of seismic effect after strong earthquakes (Shakemap generation) and seismic hazard assessment, both deterministic and probabilistic approaches.

Scaling relations of moment magnitude, local magnitude, and duration magnitude for earthquakes originated in northeast India

“…For example, ground motion prediction equations for peak ground acceleration and velocity are usually expressed as functions of M W (e.g., Atkinson and Boore 2006;Akkar and Bommer 2007;Sokolov et al 2008). For this reason, it is usual to find empirical formulae relating M W to the magnitude scales used locally in seismological practice.…”

Shake Map Methodology for Intermediate-Depth Vrancea (Romania) Earthquakes

“…From the simulated ground motion records, the authors derived empirical attenuation relationships for peak motions PGA and PGV in each of the eight characteristic regions in Figure 1. For rock site condition, Sokolov et al (2008) found…”

“…The region outlining is based on observations of weak and strong ground motions during past Vrancea earthquakes and, to a lesser extent, on geological and geomorphic characteristics (Sokolov et al 2008). For the shake-map approach, we treat each of the eight zones separately from the others by using region-specific (azimuthdependent) amplification functions and attenuation relations.…”

“…By the averaging of Fourier amplification spectra at sites within each of the eight characteristic regions outlined in Figure 1, Sokolov et al (2008) determined generalized region-specific amplification functions as displayed in Figure 2. Certain ground motion parameters, in particular PGA, may be sensitive to the amplitudes of individual peaks in the amplification spectrum.…”

“…Averaging site amplification functions over different earth- (1) North, (2) East, (3) Focsani, (4) Vrancea, (5) South, (6) Southwest, (7) Rock (Mountain), and (8) Transylvania. The region outlining is based on seismological observations during past Vrancea earthquakes and, to lesser extents, on geological and geomorphologic site conditions (Sokolov et al 2008). quakes and stations, however, smoothes these peaks and can hence lead to an underestimation of true ground shaking. Recent studies showed that the majority of observed PGA values can be reproduced when using the mean and the mean plus one standard deviation of the generalized amplification functions (Sokolov et al 2004a, b).…”