Seismic microzonation study on nonlinear site-specific ground response of Burdur soils (SW Türkiye)

The Burdur settlement area is highly prone to earthquake activity due to its location on an active fault and its predominantly unconsolidated Quaternary alluvial deposits. This study presents a site-specific microzonation based on one-dimensional nonlinear ground response analysis (NLGRA) and evaluates the local seismic hazard. A probabilistic seismic hazard analysis was conducted to generate seismic hazard curves based on different earthquake hazard levels, ground types, and spectral periods defined in the 2018 Türkiye Building Earthquake Code (TBEC 2018). Spectral amplification factors (SAFs) were determined using three methods: 1) a hybrid ground motion prediction equation, 2) amplification factors from TBEC 2018 and Eurocode 8, and 3) the results of the NLGRA. The amplification factors estimated using NLGRA exceeded those from TBEC 2018 and Eurocode 8, with maximum values of 2.58 and 2.88, respectively, in the periods corresponding to the natural vibration periods of the structures in the study area. These findings indicate that buildings in the region may be subjected to considerably higher dynamic loads than those anticipated by current seismic codes. SAFs of up to 3.51 were determined close to Burdur Lake. An increasing trend in long-period SAFs was observed in the southeast-northwest direction, correlating with the increasing thickness of alluvial deposits. The results further emphasize the importance of taking into account resonance phenomena, especially for periods exceeding 0.5 s.