A simulation-based regional ground-motion model for Western Turkiye

We developed a simulation-based ground motion model (GMM) for Western Turkiye emphasizing the regional differences between the Aegean and Marmara regions in terms of stress parameter, geometrical spreading, anelastic attenuation, and site amplification. The developed GMM also accounts for V_S (shear wave) versus kappa (high-frequency diminution) adjustment tailored for average kappa and V_S variation at the strong-motion sites in Turkiye. Our model predicts 5%-damped horizontal spectral acceleration ordinates for periods between 0.01 s ≤ T ≤ 10 s, PGA and PGV. The horizontal component definition is the geometric mean, and it can be used for moment magnitudes between 3.5 ≤ M_w ≤ 8.0, and rupture distances R_rup ≤ 400 km. We represented the aleatory variability by a partially non-ergodic sigma. Our comparisons with the recent data-driven local and pan-European GMMs advocate the significance and prevalent nature of regional effects on the predicted ground-motion amplitudes. The case studies we performed by the model also emphasize the different nature of ground motion amplitudes between the Aegean and Marmara regions dominated by the respective extensional and transform shallow active tectonic regimes. Our model inherently captures the variability in the above random predictor variables, which enables the seismic hazard analyst to reflect them on the annual exceedance probability distributions of the ground-motion amplitudes.