Supershear source model of the 2025 M7.8 Myanmar earthquake and paleoseismology of the Sagaing Fault: regions of significant overlap with past earthquakes

Diego Melgar , Ray Weldon, Yu Wang, Mary Grace Bato, Lin Thu Aung, Xuhua Shi, Weerachat Wiwegwin, Saw Ngwe Khaing, Soe Min, Myo Thant, Cole Speed, Robert Zinke, Eric Jameson Fielding , Aron Meltzner, Timothy Dawson

The 2025 Mw 7.8 earthquake on the central Sagaing Fault is one of the most destructive seismic events in Myanmar's recorded history, producing near-fault shaking exceeding Modified Mercalli Intensity X and impacting tens of millions of people across Southeast Asia. We present a detailed kinematic rupture model of the event based on joint inversion of regional strong motion waveforms and Sentinel-1 SAR pixel offsets. The rupture extended over ~450 km with an average slip of 3–5 m, predominantly within the upper 10 km of the crust. Inversions favor a maximum rupture speed of ~4.8 km/s, consistent with supershear propagation inferred from near-field waveform observations. We also report on paleoseismic evidence from a key site at the epicenter of the 2025 earthquake near Mandalay, which reveals at least five surface-rupturing earthquakes over the past millennium, with similar average displacement. Our results indicate a pattern of overlapping large ruptures along the central fault, with implications for segmentation, recurrence, and seismic hazard. Given the exceptional exposure and high strain rates, our findings underscore the need for urgent attention to earthquake preparedness and infrastructure resilience in central Myanmar.