Empirical ground-motion models for point- and extended-source crustal earthquake scenarios in Europe and the Middle East

This article presents the latest generation of ground-motion models for the prediction of elastic response (pseudo-) spectral accelerations, as well as peak ground acceleration and velocity, derived using pan-European databases. The models present a number of novelties with respect to previous generations of models (Ambraseys et al. in Earthq Eng Struct Dyn 25:371-400, 1996, Bull Earthq Eng 3:1-53, 2005; Bommer et al. in Bull Earthq Eng 1:171-203, 2003; Akkar and Bommer in Seismol Res Lett 81:195-206, 2010), namely: inclusion of a nonlinear site amplification function that is a function of V-S30 and reference peak ground acceleration on rock; extension of the magnitude range of applicability of the model down to 4; extension of the distance range of applicability out to 200 km; extension to shorter and longer periods (down to 0.01 s and up to 4 s); and consistent models for both point-source (epicentral, R-epi and hypocentral distance, R-hyp ) and finite-fault (distance to the surface projection of the rupture, R-JB) distance metrics. In addition, data from more than 1.5 times as many earthquakes, compared to previous pan-European models, have been used, leading to regressions based on approximately twice as many records in total. The metadata of these records have been carefully compiled and reappraised in recent European projects. These improvements lead to more robust ground-motion prediction equations than have previously been published for shallow (focal depths less than 30 km) crustal earthquakes in Europe and the Middle East. We conclude with suggestions for the application of the equations to seismic hazard assessments in Europe and the Middle East within a logic-tree framework to capture epistemic uncertainty.