High-frequency ground motion scaling and ground shaking scenarios for earthquakes in central Greece

Abstract

Assessing seismic hazard is important to consider whilst studying the seismology of a region. For seismologists and structural engineers, earthquake ground motion prediction is a crucial aspect of their work. Latest national hazard maps facilitate the planning and design of earthquake resistant infrastructure. These maps are produced after a precise calibration of ground motion predictive relationships, which are calculated as a function of distance from the source, magnitude, and frequency for the region using various mathematical and data processing techniques such as regression analysis. The aim of this study is to provide a complete description of the characteristic of the ground-motion for the Corinth Gulf region, for which this has not been done so far. Waveforms from around 297 events were obtained from 65 three-component stations around central Greece, all part of the Hellenic Unified Seismic Network. For this region, we employed a general form for a predictive relationship including the source excitation term, an attenuation operator and an operator to account for the site effect. The functional form of the crustal attenuation term depends principally on the attenuation parameter and on the geometrical spreading. Excitation terms are modelled by using a Brune spectral model. Simulations are carried out using EXSIM and ground motion scenarios (in terms of peak ground acceleration and peak ground velocity as a function of magnitude and distance) are computed for the study area. Furthermore, it is envisaged that the results obtained can later be used for upgrading seismic hazard maps and for engineering designs as well as implementing tools like ShakeMap®, as well as to be used for implementing evacuation plans and risk mitigation strategies.