Abstract:

The Eastern Anatolia suffered devastation following two major earthquakes on 6 February 2023 causing collapse of numerous structures and resulting in tens of thousands of human casualties, injuries, and displacements. This research endeavors to elucidate factors related to building properties and earthquake environmental effects (EEEs) that control the grade and distribution of structural damage in southeastern Turkey. The outcomes delineated herein originate from post-event field surveys conducted by the authors shortly after the earthquakes. The field surveys encompassed geological mapping techniques alongside novel methodologies, such as the utilization of Unmanned Aerial Systems (UAS).
In terms of building construction characteristics, deficiencies such as inadequate compliance with building codes, arbitrary urban planning solutions, and inferior construction practices represent primary factors that contributes significantly to the disaster. Regarding geological factors, both primary and secondary EEEs played a significant role in controlling the severity and distribution of building damage. Primary EEEs, in particular coseismic surface ruptures along segments of the East Anatolian Fault (EAF), intersected with urban regions exhibited severe to severe structural damage (e.g. Gölbaşı, Balkar, Sekeroba, Nurdağı, İslahiye, Hassa towns etc.). Liquefaction along with lateral spreading and subsidence near water bodies (sea, existing and former lakes and rivers in the affected area) resulted in damage indicative of compromised building foundation load-bearing capacity (e.g. İskenderun, Gölbaşı and Antakya cities). Typical damage included sinking and tilting of buildings, damage due to pounding of adjacent structures, as well as outspread multi-layer and pancake-type collapse. Earthquake-triggered landslides (ETILs) predominantly affected mountainous and semi-mountainous villages. The collision of the mobilized rock fragments with adjacent structures and the presence of structures within the landslide boundaries are the main mechanisms of building damage due to ETILs. The synergy of high landslide susceptibility and liquefaction potential resulted in destruction in several urban centers of the earthquake-affected area (e.g. Kahramanmaraş city).