A regionally-adaptable ground-motion model for shallow crustal earthquakes in Europe
Résumé
Abstract To complement the new European Strong-Motion dataset and the ongoing efforts to update the seismic hazard and risk assessment of Europe and Mediterranean regions, we propose a new regionally adaptable ground-motion model (GMM). We present here the GMM capable of predicting the 5% damped RotD 50 of PGA , PGV , and $$ SA\left( {T = 0.01 - 8\,{\text{s}}} \right) $$ S A T = 0.01 - 8 s from shallow crustal earthquakes of $$ 3 \le M_{W} \le 7.4 $$ 3 ≤ M W ≤ 7.4 occurring $$ 0 < R_{JB} \le 545\,{\text{km}} $$ 0 < R JB ≤ 545 km away from sites with $$ 90 \le V_{s30} \le 3000\,{\text{m}}\,{\text{s}}^{ - 1} $$ 90 ≤ V s 30 ≤ 3000 m s - 1 or $$ 0.001 \le slope \le 1\,{\text{m}}\,{\text{m}}^{ - 1} $$ 0.001 ≤ s l o p e ≤ 1 m m - 1 . The extended applicability derived from thousands of new recordings, however, comes with an apparent increase in the aleatory variability ( σ ). Firstly, anticipating contaminations and peculiarities in the dataset, we employed robust mixed-effect regressions to down weigh only, and not eliminate entirely, the influence of outliers on the GMM median and σ . Secondly, we regionalised the attenuating path and localised the earthquake sources using the most recent models, to quantify region-specific anelastic attenuation and locality-specific earthquake characteristics as random-effects, respectively. Thirdly, using the mixed-effect variance–covariance structure, the GMM can be adapted to new regions, localities, and sites with specific datasets. Consequently, the σ is curtailed to a 7% increase at T < 0.3 s, and a substantial 15% decrease at T ≥ 0.3 s, compared to the RESORCE based partially non-ergodic GMM. We provide the 46 attenuating region-, 56 earthquake localities-, and 1829 site-specific adjustments, demonstrate their usage, and present their robustness through a 10-fold cross-validation exercise.
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Licence : CC BY - Paternité
Licence : CC BY - Paternité