GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Geodetc Modelling of the 2023 M W 7.8 and 7.6 Türkiye Earthquake Sequence D. Cheloni 1 , N. A. Famigliet 2 , A. Akinci 1 , R. Caputo 3 , A. Vicari 2 1 Isttuto Nazionale di Geofsica e Vulcanologia, Rome, Italy 2 Isttuto Nazionale di Geofsica e Vulcanologia, Sezione Irpina, Italy 3 Department of Physics & Earth Sciences, Ferrara University, Italy On 6 February 2023 a M W 7.8 earthquake occurred at 01:17 UTC in south-eastern Türkiye, near the Pazarcık district in Kahramanmaraş province close to the northern border of Syria (Fig. 1). It was followed 9 hours later by a M W 7.6 earthquake approximately 90 km to the north, resultng in widespread destructon of buildings and signifcant loss of life. The largest afershocks occurred on 6 February and 20 February, and their magnitudes have been assessed as M W 6.7 and 6.4, respectvely. According to the informaton provided by the Earthquake Department of the Disaster and Emergency Presidency (AFAD) there were over 50,000 reported fatalites and over 100,000 injuries from the devastatng seismic sequence. The earthquakes were reported to be on diferent segments of the well-known lef-lateral contnental strike-slip East Anatolian Fault Zone (EAFZ), which is one of the two major actve strike-slip fault systems in Türkiye, other being the right- lateral North Anatolian Fault Zone (NAFZ). In this study, we analyse the main features of the rupture process during the Kahramanmaras seismic sequence. In this respect, we use Interferometric Synthetc Aperture Radar (InSAR) and Global Navigaton Satellite System (GNSS) data to investgate the ground displacement feld (inset Fig. 1) and to infer, by using elastc dislocaton modelling, the fault geometry and slip distributon of the causatve fault segments. We performed fault slip modelling using rectangular dislocatons embedded in an elastc, homogeneous and isotropic half-space (Okada, 1985). We constrain the trace of the rupture surface of the earthquake doublet by examinaton of the displacements in the near-feld InSAR data, extending the fault planes to a depth of 20 km running through the relocated seismicity (Lomax, 2023). The geodetc data is thus inverted for slip magnitude on each fault patch, inferring the optmal geometry iteratng over dips and rake angles of the fault planes (Cheloni et al., 2019). In our inversion scheme, we consider 3 main fault segments with variable orientaton for the M W 7.8 main shock (Amanos, Pazarcık and Erkenek segments) and 2 main fault segments for the M W 7.6 event (the Çardak-Savrun fault and an eastward segment located along the Nurhak complexity). In additon, we also include a segment located in the Narlı Fault Zone, a small splay