Supplementary Information for Seismic forecasting insights from slip patterns before 2025 and 2023 earthquakes in Myanmar and Türkiye

Despite major advances in seismology, earthquake forecasting and early warning systems remain inadequate for the catastrophic loss of life and infrastructure occurring in major events. The 2025 Mw7.7 Myanmar earthquake and the 2023 doublet of Mw≥7.6 earthquakes in Türkiye claimed over 60,000 lives. They were generated by the Sagaing Fault in Myanmar and the East Anatolian Fault in Türkiye, each over 700 km long, forming active plate boundaries, and repeatedly producing devastating earthquakes. Understanding how such faults evolve in the years before major earthquakes is therefore critical. Here, we analyze the spatiotemporal evolution of seismic moment release over the 1,000 days preceding the three recent mainshocks and identify common trends and key differences. The Myanmar earthquake was preceded by a sharp increase in energy release followed by ~50 days of seismic quiescence. The Türkiye earthquakes were marked by a gradual focusing of seismicity along most segments, a gradual increase of seismic moment, and a ~250-day premainshock quiescence on the fault segment of the second mainshock. Understanding these trends and differences provides critical information for earthquake preparation and forecasting. Fault zone properties such as maturity and segmentation offer valuable insights for future behavior and earthquake precursors.