Geometric controls on cascading rupture of the 2023 Kahramanmaraş earthquake doublet

How fault geometry controls the rupture propagation and segmentation of a strike-slip event is an open question. Deciphering the relationship between the geometric fault complexity and seismic kinematics is essential for both understanding the seismic hazard posed by a particular fault and gaining insights into the fundamental mechanics of earthquake rupture. Here we integrate the finite-fault inversion of synthetic aperture radar observations and back projection of high-frequency teleseismic array waveforms to investigate the rupture geometry of the 2023 M w 7.8 and M w 7.6 Kahramanmaraş (southeastern Turkey) earthquake doublet and its impact on the kinematics and slip distribution. We find that large slip asperities are separated by fault bends, whereas intense high-frequency (~1 Hz) sources occur near the branching junctions, suggesting that geometric barriers could decelerate rupture propagation and enhance high-frequency wave radiations. In addition, supershear rupture propagating along the relatively high-velocity material is prone to occur on geometrically simple and smooth faults with relatively few aftershocks. These kinematic characteristics highlight that the geometric complexity of the fault system may be a key factor in the irregular cascading rupture process. Analysis of remote-sensing and seismological observations from the 2023 Kahramanmaraş earthquake doublet reveals how fault geometry can control fault slip distribution and rupture kinematics, including the occurrence of supershear rupture.