Comparison of Backprojection Techniques for Rupture Propagation Modelling of the Mw = 7.8 Mainshock Earthquake near Kahramanmaras and the Mw = 7.5 Second-Largest Mainshock near Elbistan, Turkey, 2023

This paper utilises teleseismic Z-component data to investigate rupture propagation, extent, and velocity for two very destructive earthquakes in the East Anatolian Fault Zone (EAFZ): the Mw = 7.8 earthquake near Kahramanmaras and the largest (Mw = 7.5 s) aftershock at Elbistan (both on 6 February 2023). The extent of the rupture is modelled with beamforming and multichannel signal classification. The teleseismic data are derived from agencies in USA and Canada. The rupture of the Mw = 7.8 earthquake is found to be bi-directional towards the northeast and southwest. Three rupture segments are identified for the Kahramanmaras earthquake between 34.5°–37.5° longitude and 37.0°–37.5° latitude, and another three are identified for the Elbistan earthquake between 36.5°–38.0° longitude and around 38.5° latitude. A total of 299 km is covered in 185 s with rupture velocities between 3.1 km/s and 3.4 km/s. Additionally, the mainshock’s splay and the second-largest aftershock’s rupture are also bidirectional, covering 150 km within 46 s. Five velocity segments are identified, three for the Kahramanmaras and two for the Elbistan earthquakes. Beamforming is efficient for identifying the velocity segments. The findings provide new insights on the evolution of the spatio-temporal rupture of the EAFZ and may serve as a basis for long-term earthquake hazard planning in the area.