GIS-Based Mapping and Assessment of Seismic Hazard and Soil Classification in Elazığ City Center, Turkey

In this study, analyses of soil classifications and earthquake hazard parameters were conducted for the city center of Elazığ, located in the Eastern Anatolia region of Turkey, using data from 210 boreholes obtained from a 133.65 km² study area. The evaluations were performed based on EUROCODE and NEHRP soil classification systems, as well as earthquake hazard parameters derived from soil amplification calculations, by utilizing Geographic Information Systems (GIS). For this purpose, field data such as compressional wave velocity (Vp), shear wave velocity (Vs), and average shear wave velocity up to 30 m (VS30) were used to classify the soils according to the EUROCODE and NEHRP systems, and to generate GIS-based maps representing the earthquake hazard levels according to site amplification. As a result, based on the NEHRP classification, 2% of the study area was identified as hard rock (Class A), 69% as rock (Class B), and 29% as very dense soil and soft rock (Class C). According to Eurocode 8, 35% of the area was classified as very dense sand or gravel or very stiff clay, while 65% was classified as dense sand or gravel or stiff clay. Based on the site amplification analysis, 1% of the area was found to correspond to Class B (moderate hazard), while the remaining 99% corresponded to Class C (low hazard). No areas were identified as Class A (high hazard). Overall, it was determined that low earthquake hazard levels predominate across the study area.