The 2020 update of the European Seismic Hazard Model: Model Overview. EFEHR Technical Report 001, v1.0.0

Abstract

Executive Summary The 2020 European Seismic Hazard Model (ESHM20) provides an update of the earthquake hazard assessment of the Euro-Mediterranean region. ESHM20 has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No.s 730900 of the SERAProject (www.sera-eu.org) The ESHM20 follows the same principles as the ESHM13, with state-of-the art procedures homogeneously applied for the entire pan-European region, without the country-borders issues. The model was built upon recently compiled datasets (i.e. earthquake catalogues, active faults, ground shaking recordings), information (tectonic and geological) and models (seismogenic sources, ground shaking). A fully probabilistic framework was adopted in the hazard model implementation and all datasets and inputs are fully cross-border harmonized. The newly developed seismogenic source model encompass fully harmonized and cross borders seismogenic sources following the recent national earthquake hazard models. The inherent uncertainties in characterizing the earthquake rupture forecast are handled by a complex logic tree, consisting of two main models (branches): an area source-based model and a hybrid fault-smoothed seismicity model. The ground motion characteristic model is built upon the most complete ground shaking recordings in Europe and aims at capturing the effects of source and attenuation path of the expected ground shaking at a site. The regional variability of the ground shaking as constrain by observations is captured by a novel approach of spatial clustering and the overall uncertainties are handled in a backbone logic tree. The master logic tree combines the earthquake rate forecast with the backbone ground motion models into a computational model for assessing the earthquake ground shaking at across the entire Euro- Mediterranean region. Full sets of hazard results (i.e. hazard curves and maps, uniform hazard spectra) for various combinations of return periods and descriptive statistics (mean, median and quantiles) are available. The ESHM20 development process involved several regional workshops where the scientists and experts were consulted and their feedback was acknowledged and considered on the model outcome. Finally, ESHM20 provides the basis to derive informative hazard maps for two key engineering parameters defining the anchoring points of the seismic design spectra for the next version of the European Seismic Design Code (CEN-EC8). The European Facilities for Earthquake Hazard and Risk (EFEHR) will maintain and further develop this model in collaboration with the GEM Foundation and the European Plate Observing System (EPOS). The source data, input models, software and outputs of ESRM20 are thus being openly released with a Creative Commons CC-BY International 4.0 license (https://creativecommons.org/licenses/by/4.0/). This license allows re-users to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. Each product is released with a clear notice on how it should be cited in order to abide by the license. ESHM20 is online available at the www.hazard.EFEHR.org.