Stochastic finite fault simulation of 2023 Mw 7.8 and Mw 7.5 Turkey earthquakes and its application to regional buildings damage estimation at Kahramanmaras City

On February 6, 2023, an M_w 7.8 earthquake occurred in southern Turkey, and only nine hours later, an M_w 7.5 earthquake occurred 95 km north of the first earthquake epicenter. This study employed stochastic finite fault method to simulate the ground motions from the earthquake doublet. The input parameters of source, path, site are mostly determined by regression of station records. The simulated ground motions are validated by comparing with eight station records, and results show that simulated PGA, waveform, PSA curve, duration match with those from station records with minor discrepancies. In addition, goodness-of-fit evaluation is also performed. Regional building damage estimation results show that severely damaged and collapsed buildings increased from 28 to 42% after the second earthquake, and 1/4 buildings damage state experienced one-level jump, which indicates that the second earthquake might significantly intensify buildings damage and should be carefully evaluated within an earthquake doublet context. The stochastic finite fault simulation in this study could provide a basis for future studies on the Turkey earthquake doublet, and the regional buildings damage estimation could be helpful for improvement of earthquake rescue and disaster mitigation policies.