OUTLINE OF THE JOINT RECONNAISSANCE OF THE FEBRUARY 2023 KAHRAMANMARAŞ AND HATAY EARTHQUAKES

Two strong earthquakes hit southern Turkey on February 6th, 2023 with magnitudes measuring at M7.8 (Pazarcık, Kahramanmaraş) and M7.5 (Elbistan, Kahramanmaraş), followed by another strong earthquake with a magnitude of M6.4 on February 20th, 2023 (Hatay). These earthquakes were devastating and caused severe building damages and collapses in addition to a huge number of casualties (over 50.000) and economic losses over a wide area, where more than 10 million people were living. Given the devastating situation, a special project was organized as a part of the Grants-in-Aid for Scientific Research by the Japan Society for the Promotion of Science (KAKENHI). KAKENHI, Architectural Institute of Japan, Japan Society of Civil Engineering, and Japan Geotechnical Society agreed to dispatch a joint reconnaissance team to the affected area. In total, a group of 27 researchers and practitioners was dispatched from Japan. More than 20 researchers joined this group from different institutions in Turkey (Istanbul Technical Univ., Boğaziçi Univ., Yıldız Technical Univ., Mimar Sinan Univ., İzmir Yüksek Teknoloji Univ., Harran Univ., MEF Univ. and Kültür Univ. among others) to conduct the joint reconnaissance. Investigations covered reinforced concrete (RC) structures, steel structures, wall structures, masonry structures, hospitals, base-isolated buildings, geotechnical damage, building codes, regulations and inspection systems. The investigations were conducted from March 29th to April 4th. The target cities were Gaziantep, Osmaniye, Hatay, Kahramanmaraş, Adıyaman and Adana. In these cities, buildings damaged to different extents were investigated to assess the damage and to evaluate possible causes of the damages. Twenty-five buildings were investigated in detail in terms of damages of structural and non-structural members, as well as the member dimensions and bar arrangements to conduct Japanese and Turkish damage classification. Damage ratios around the eight strong motion observatory stations were also investigated. This study summarizes the activities of the team and outcomes of the field investigations in terms of strong ground motions, geotechnical damage, industrial buildings, hospital buildings, RC buildings, codes and regulations, and housing reconstruction.