Ryo Okuwaki , Yuji Yagi, Tuncay Taymaz, Stephen Paul Hicks 

A devastating doublet of earthquakes with moment magnitude Mw 7.9 and Mw 7.6 earthquakes contiguously occurred in SE Türkiye near the NW border of Syria. Here we perform a potency-density tensor inversion to simultaneously estimate rupture evolution and fault geometry for the doublet. We find the initial Mw 7.9 earthquake involved discrete episodes of supershear rupture and back-rupture propagation, and was triggered by initial rupture along a bifurcated splay of the East Anatolian Fault. The second Mw 7.6 event was triggered by the earlier Mw 7.9 event, and it involved more extensive supershear rupture along a favorably curved fault, and was likely stopped by geometric barriers at the fault ends. Our results highlight the multi-scale cascading rupture growth across the complex fault network that affects the diverse rupture geometries of the 2023 Türkiye earthquake doublet, contributing to the strong ground shaking and associated devastation.