Multi-criteria microzonation Hazard assessment based on the analytic hierarchy process framework

This study presents a seismic microzonation assessment of the Erenler district (Sakarya, Türkiye), located along the North Anatolian Fault Zone. A total of 37 ambient noise, 50 seismic, and 51 borehole datasets were integrated to evaluate local site effects. Predominant frequency ranges 0.83−12.5 Hz, while engineering bedrock depth varies between 9 and 286 m. The average 30-meter shear wave velocity spans from 144 to 523 m/s, with the lowest values observed in northern Quaternary alluvium and the highest in southern zones with coarse sediments. 1D nonlinear site response analysis for the 1999 İzmit Earthquake scenario yield peak ground accelerations of 0.08–0.41 g, and spectral accelerations frequently exceed design spectra, particularly at 1.0 s periods. Liquefaction potential, evaluated using the liquefaction potential index and the Ishihara boundary curve, indicates high susceptibility in areas with shallow groundwater and silty sands. However, areas underlain by thick non-liquefiable layers (>3–7.5 m) exhibit no evidence of surface manifestations. An integrated seismic hazard index map, produced by weighting seven criteria within the Analytic Hierarchy Process (AHP) framework, reveals high and very high hazard zones north of the Sapanca–Akyazı fault segment. The findings confirm the effectiveness of AHP-based microzonation for seismic risk mitigation and urban planning.