2023 Turkish earthquake doublet, back projection method, cascading segmented rupture process, coseismic triggering, super-shear ruptures, Geology, QE1-996.5

In this study, the vertical components of broadband teleseismic P wave data recorded by China Earthquake Network are used to image the rupture processes of the February 6th, 2023 Turkish earthquake doublet via back projection analysis. Data in two frequency bands (0.5–2 Hz and 1–3 Hz) are used in the imaging processes. The results show that the rupture of the first event extends about 200 km to the northeast and about 150 km to the southwest, lasting ∼90 s in total. The southwestern rupture is triggered by the northeastern rupture, demonstrating a sequential bidirectional unilateral rupture pattern. The rupture of the second event extends approximately 80 km in both northeast and west directions, lasting ∼35 s in total and demonstrates a typical bilateral rupture feature. The cascading ruptures on both sides also reflect the occurrence of selective rupture behaviors on bifurcated faults. In addition, we observe super-shear ruptures on certain fault sections with relatively straight fault structures and sparse aftershocks.