Journal Articles Journal of Seismology Year : 2024

Impact of Mw definition approach on Fourier ground-motion variability of shallow crustal earthquakes in Europe

Abstract

A Ground-motion Model (GMM)'s apparent aleatory variability is inflated by errors in its predictor parameters, specifically the moment magnitude (Mw). Multiple Mw values can be available for an event (direct or deduced) and various Mw definition approaches have been proposed to assign a unique Mw value to an event. In this study, we investigate the impact of Mw definition on a pan-European Engineering Strong Motion dataset based Fourier GMM, using two datasets with Mw defined by two distinct approaches: [1] the ranking strategy of the Euro-Mediterranean Earthquake Catalogue (EMEC 2019) and [2] the multi-strategy (standardization, ranking, unification, averaging) approach to Mw definition of Laurendeau et al. (2022). Large discrepancies in Mw values can be observed especially between Mw ranging from 4.0 to 5.0. While the GMM median predictions remain unchanged irrespective of dataset, we report a large reduction in between-event variability of the GMM at low frequencies (< 1.8 Hz) when strategy [2] is adopted over [1] (18% at 0.35 Hz). This reduction applies to frequencies before the corner-frequency of the Fourier spectrum, as this part of the spectrum depends primarily on seismic moment. We attribute this reduction to the use of direct Mw values in [2] instead of deduced Mw values in [1], the priority scheme in the ranking strategy, and the unification strategy. Our study suggests that the approach used to define a unique Mw in the GMM dataset may have a significant impact on its predictions in seismic hazard assessment.
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Avant la publication
Friday, May 9, 2025
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Friday, May 9, 2025
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irsn-04846085 , version 1 (15-01-2025)

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Aurore Laurendeau, Sreeram Reddy Kotha. Impact of Mw definition approach on Fourier ground-motion variability of shallow crustal earthquakes in Europe. Journal of Seismology, In press, ⟨10.1007/s10950-024-10254-z⟩. ⟨irsn-04846085⟩
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