A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe: regionalisation, model s
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A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe: regionalisation, model selection and development of a scaled backbone approach Graeme Weatherill1 · Fabrice Cotton1,2 Received: 17 April 2020 / Accepted: 18 August 2020 © The Author(s) 2020
Abstract Regions of low seismicity present a particular challenge for probabilistic seismic hazard analysis when identifying suitable ground motion models (GMMs) and quantifying their epistemic uncertainty. The 2020 European Seismic Hazard Model adopts a scaled backbone approach to characterise this uncertainty for shallow seismicity in Europe, incorporating region-to-region source and attenuation variability based on European strong motion data. This approach, however, may not be suited to stable cratonic region of northeastern Europe (encompassing Finland, Sweden and the Baltic countries), where exploration of various global geophysical datasets reveals that its crustal properties are distinctly different from the rest of Europe, and are instead more closely represented by those of the Central and Eastern United States. Building upon the suite of models developed by the recent NGA East project, we construct a new scaled backbone ground motion model and calibrate its corresponding epistemic uncertainties. The resulting logic tree is shown to provide comparable hazard outcomes to the epistemic uncertainty modelling strategy adopted for the Eastern United States, despite the different approaches taken. Comparison with previous GMM selections for northeastern Europe, however, highlights key differences in short period accelerations resulting from new assumptions regarding the characteristics of the reference rock and its influence on site amplification. Keywords Ground motion models · Stable craton · Regionalisation · Epistemic uncertainty · Europe
* Graeme Weatherill graeme.weatherill@gfz‑potsdam.de 1
GFZ German Research Centre for Geosciences, Potsdam, Germany
2
University of Potsdam, Potsdam, Germany
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Vol.:(0123456789)
Bulletin of Earthquake Engineering
1 Introduction Seismic hazard and risk analysis on a regional scale requires not only the characterisation of ground motion in regions of high seismic activity, but also tectonically stable regions with little seismicity. Here the infrequency of even moderate sized earthquakes limits the number of observations of strong shaking, meaning that purely empirical ground motion models (GMMs) may be poorly constrained over the ranges of magnitudes and distances considered for seismic hazard analysis. To overcome these limitations, it has become more common in engineering practice to take GMMs that are originally constructed for active regions and adjust them to the seismological conditions of the target region. This is usually done using simulations of motion that are calibrated to source, path and site properties inferred from recordings of weak motion in the target region or via other means (e.g. Campbell 2003; Pezeshk et al. 2011; PEER 2015). Given the paucity of stron
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