HYPSTHER PROJECT: HYBRID GROUND MOTION PREDICTION EQUATIONS FOR PSHA PURPOSES

Abstract

In the last decades, the calibration of reliable GMPEs became a critical issue in Probabilistic Seismic Hazard Assessment (PSHA). NGA-East project provides a set of new GMPEs for median and standard deviation of Ground Motions (GMs) and their associated weights in the logic trees for use in PSHA for Central and Eastern North-American Region. These results include the use of synthetic data to fill the lacking of observations, especially for moderate to large earthquakes in near field conditions. On the European side, some efforts have been made within the NERA EU Project for the calibration of physics-based GMPEs, which are particularly effective in showing important ground motion features in near source regions. Indeed, when the site is very close to the fault, the rupture processes are predominant and the finite-source effects, such as directivity, hanging wall/foot wall, radiation-pattern and slip distribution can dominate the GMs. Therefore, the empirical GMPEs are generally incapable to capture such features, because the strong motion recorded data in near source are few. This paper explains the aims of HYPSTHER (HYbrid ground motion prediction equations for PSha purposes: the study case of souTHERn Italy) project, devoted to develop a methodological approach to retrieve ground motion prediction models, based on the integration between recorded and synthetic data. The motivation of this research is to supply the lack of instrumental observations for moderate to large earthquakes in near fault conditions. In this framework, we will test this methodology for the study case of Southern Italy, focusing our attention on Calabria and Sicily regions. The target area has been chosen based on the expected high hazard level, despite the seismic activity has been scarce in the last decades. In addition, along the Sicily coast many critical infrastructures are present, such as chemical plants and large ports, which strongly increase the risk of technological accidents induced by natural hazards. The results of the HYPSTHER project will be a set of Ground Motion Prediction Equations (GMPEs) for PGA, PGV and SA in the period range T=0.04-4s. Additional results include recorded and synthetic ground motion datasets. The project products can be tested and incorporated in a next generation of the Italian Seismic Hazard Maps.