The recent seismic activity on Turkiye's west coast, especially in the Aegean Sea region, shows that this region requires further attention. The region has significant seismic hazards because of its location in an active tectonic regime of North-South extension with multiple basin structures on soft soil deposits. Recently, despite being 70 km from the earthquake source, the Samos event (with a moment magnitude of 7.0 on October 30, 2020) caused significant localized damage and collapse in the Izmir city center due to a combination of basin effects and structural susceptibility. Despite this activity, research on site characterization and site response modeling, such as local velocity models and kappa estimates, remains sparse in this region. Kappa values display regional characteristics, necessitating the use of local kappa estimations from previous earthquake data in region-specific applications. Kappa estimates are multivariate and incorporate several characteristics such as magnitude and distance. In this study, we assess and predict the trend in mean kappa values using three-component strong-ground motion data from accelerometer sites with known VS30 values throughout western Turkiye. Multiple linear regression (MLR) and multivariate adaptive regression splines (MARS) were used to build the prediction models. The effects of epicentral distance Repi, magnitude Mw, and site class (VS30) were investigated, and the contributions of each parameter were examined using a large dataset containing recent seismic activity. The models were evaluated using well-known statistical accuracy criteria for kappa assessment. In all performance measures, the MARS model outperforms the MLR model across the selected sites.

Soil liquefaction-induced damages in buildings and foundation during earthquakes increase the seismic hazard of densely populated urban cities dwelling on young alluvial soil deposits with a rising demand for infrastructural developments. Generally, liquefaction potential is evaluated for specific sites, which lacks the information related to the spatial extent of liquefaction effects. In the present study, liquefaction hazard maps of Kolkata metropolitan city is prepared for potential future earthquakes considering the spatial variability of soil parameters. The importance and application of geostatistical interpolation tools for hazard mapping are highlighted in this paper. Deterministic procedures of Boulanger and Idriss (2004, 2014) were utilized to quantify the liquefaction potential of two types of soil deposits, silty clay and silty sand, in the study area. Probability of liquefaction (PL) was evaluated by first-order second moment (FOSM) reliability method for 2% and 10% probability of exceedance in 50 years. Python codes were developed for the calculation of factor of safety (FS) and PL values for silty sand and silty clay. Spatial distribution maps in terms of FS and PL were generated at 7 m, 15 m and 25 m depth of the study area using ordinary kriging technique in ArcGIS software. The regions of Maidan, Newtown, Rajarhat, Santoshpur, Sector V and Tangra were found to be vulnerable to liquefaction till 15 m depth. Additionally, correlations were also developed between PL and FS using non-linear regression analysis for all soils, silty clay and silty sand of the study area for both the probabilistic scenarios.