ALBERT

Description: On 6 February 2023, an M〈sub〉W〈/sub〉 7.8 earthquake occurred on the southwestern part of the East Anatolian Fault zone (EAF), followed by an M〈sub〉W〈/sub〉 7.5 at ~100 km away on the East-West striking Sürgü fault 9 hours later. The W-Phase inversions indicate major strike-slip with dip angles of 60° for both events. A notable difference in seismic waveforms between two major earthquakes suggests different rupture characteristics. High-frequency back projection images for the M〈sub〉W〈/sub〉 7.8 event from the dense broadband ChinArray shows a NE unilateral rupture from the onset for 40 sec with the expansion to the EAF trace since ~20 s and stopping at the junction of EAF and Sürgü fault, along with some late radiation at ~40-60 s to SW at the Amanos segment of EAF. The back projection image for the M〈sub〉W〈/sub〉 7.5 event shows a main high-frequency coherent energy release for the first 10 sec over ~40 km and late weak radiations to the west near the curved Cardak fault and to the east near the Malatya fault. Preliminary slip models inverted from teleseismic data indicate a complex rupture for the M〈sub〉W〈/sub〉 7.8 event predominantly on the EAF and a localized slip for the M〈sub〉W〈/sub〉 7.5 event. The difference also exhibits in body-wave magnitude with m〈sub〉B〈/sub〉=7.5 for the M〈sub〉W〈/sub〉 7.5 and m〈sub〉B〈/sub〉=7.2 for the M〈sub〉W〈/sub〉 7.8 events. We are exploring InSAR images, hr-GNSS, and strong-motion data to constrain details in the rupture process of both events.