Interactions, stress changes, mysteries, and partial forecasts of the 2023 Kahramanmaraş, Türkiye, earthquakes

Brought closer to failure by the Feb. 6, 2023, magnitude-7.8 shock, the magnitude-7.5 shock that struck nine hours later caused aftershocks to turn on in some zones and off in others. But why both shocks nucleated on secondary faults — one quite small, the other misaligned for failure — is unclear. Moreover, decades earlier, two independent groups noted the heightened risk of large earthquakes in the approximate location of the magnitude-7.8 event.