Seismic Site Classification Via V S30 and SPT-N Values in Antakya City, Türkiye

The paper presents an assessment for the seismic site classification (SSC) in Antakya city located in southern central Türkiye, strongly affected by three destructive earthquakes of 7.7 Mw took place in Pazarcik (Kahramanmaras) on February 6, 2023, 7.6 Mw took place in Elbistan (Kahramanmaras) on February 6, 2023, and 6.4 Mw took place in Defne (Hatay) on February 20, 2023. The VS30 and SPT-N values have been used to identify the SSC in the region with respect to the provisions recommended by the National Earthquake Hazards Reduction Program (NEHRP), Design of Structures for Earthquake Resistance (Eurocode 8), and Turkish Building Earthquake Code (TBEC). The values of SPT-N were recorded from the field works that include 630 boreholes in the top 30 m, whilst the VS30 was calculated through the multichannel analysis of surface waves (MASW) method performed at 977 different locations across the region. The results showed that approximately 51% and 44% of soils in the city of Antakya has been classified as Class C and Class D, respectively, in accordance with the NEHRP and TBEC, whilst 52% and 44% of the same region has been classified as Class B and Class C, respectively, in accordance with the Eurocode 8. Furthermore, a newly proposed correlation as well as already available ones between the VS30 and SPT-N values have been presented comparatively by an extensive series of GIS maps produced in order to have a much clear understanding on the various soil types in Antakya. Evidently, the results of this research should be of a great significance for researchers and practitioners working on the earthquake-resistant structures, prediction of ground movements, and in seismic risk assessments.