Tepehan Rockslide: A large-scale earthquake-induced geological structure formed by Mw:7.8 Kahramanmaraş (Pazarcık) earthquake, Türkiye

Three devastating and powerful earthquakes hit the southeastern and eastern parts of Turkiye and the northestern part of Syria in February of 2023, causing many earthquake-induced slope movements. One of these major mass movements is called the "Tepehan Rockslide", which was formed by the first Mw: 7.8 earthquake on February 6th, 2023 at Pazarcik (Kahramanmaras) located in the Altinozu district of Hatay province. The rockslide involved the movement of Middle Miocene basement rocks that consist of clayey limestone, marl, and fine-grained clastic sedimentary rocks. The morphogenetic evaluation of the structure reveals that the Tepehan Rockslide is a very rapidly developed translational interrupted ridge type earthquake-induced large-scale rockslide or a large rock glide that was formed at a distance of 19 km from the surface rupture and 136 km from the earthquake epicentre. Field observations and centimeter-precise numerical data via high resolution Unmanned Aerial Vehicle (UAV) footage with a GNSS-RTK mounted module reveal that the approximately E-W oriented longest axis of the structure is 496 m, and the widest profile is 184 m, extending in N-S direction. The total moving mass has been calculated to cover ca. 71,000 m2 surface area, with an average volume of at least 1.1 million m3 and total a weight of 2.75 megatons. Comparisons made with its counterparts worldwide show that the Tepehan Rockslide is not a unique earthquake-induced slope movement by itself. However, it is the largest of the detected voluminous rockslide type slope movements formed in the region during the February 2023 earthquakes.