Empirical Peak Ground-Motion Predictive Relations for Shallow Earthquakes in Greece

Abstract

In the present article new predictive relations are proposed for the peak values of the horizontal components of ground acceleration, velocity, and displace- ment, using 619 strong motion recordings from shallow earthquakes in the broader Aegean area, which are processed using the same procedure in order to obtain a homogeneous strong motion database. The data set is derived from 225 earthquakes, mainly of normal and strike-slip focal mechanisms with magnitudes 4.5 M 7.0 and epicentral distances in the range 1 km R 160 km that have been relocated using an appropriate technique. About 1000 values of peak ground acceleration (PGA), velocity (PGV), and displacement (PGD) from horizontal components were used to derive the empirical predictive relations proposed in this study. A term ac- counting for the effect of faulting mechanisms in the predictive relations is intro- duced, and the UBC (1997) site classification is adopted for the quantification of the site effects. The new relations are compared to previous ones proposed for Greece or other regions with comparable seismotectonic environments. The regression anal- ysis showed a noticeable (up to 30%) variance reduction of the proposed relations for predicting PGA, PGV, and PGD values compared to previous ones for the Aegean area, suggesting a significant improvement of predictive relations due to the use of a homogeneous strong motion database and improved earthquake parameter infor- mation.