Geotechnical and geophysical investigations on local site effects in Erzurum, Türkiye

This study presents the geotechnical and geophysical properties of different historical and modern settlement areas in the City of Erzurum, Türkiye, with an emphasis on assessing local site effects based on microtremor measurements. Erzurum City is located near the north and east Anatolian fault zones, making it a seismically active region. As a result, Erzurum is highly vulnerable to earthquakes. To study these risks, data was collected using the Horizontal-to-Vertical Spectral Ratio (HVSR) technique from four different sites of Kahramanlar (Karaz), Kombina, Kale, and Palandöken Toki at the Erzurum Basin. The research highlights variations in soil properties such as dominant ground frequency and period, shear wave velocity (Vs30), and the vulnerability index (Kg). Results provide valuable insights into site amplification and the potential seismic hazard in the region. Areas with lower dominant frequencies, indicating deeper sediment layers, are more prone to seismic amplification and greater risk. In contrast, regions closer to mountainous areas, with higher dominant frequencies, show reduced vulnerability. These results are crucial for understanding seismic behavior and will play a key role in guiding the development of earthquake-resistant infrastructure in Erzurum.