A study published May 7 in Science analyzed the 7.7-magnitude earthquake that struck Myanmar in March 2025, killing over 3,600 people and causing economic losses equal to 14% of the nation’s GDP. The quake occurred near Mandalay along the Sagaing Fault, one of Southeast Asia’s most active.

Though Sagaing appears geologically simple—long and straight without sharp bends—researchers found its behavior highly complex. Using radar satellite data, they tracked surface changes during the quake, then combined them with computer models simulating centuries of tectonic stress buildup. Lead author Sylvain Barbot of USC explained that rupture extended nearly 450 km, comparable to Los Angeles–San Francisco distance, showing the quake was not confined to one segment but spread widely.
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Surprisingly, different fault sections moved at slightly different speeds, varying by 10–20%. Over centuries, such differences create uneven stress accumulation, influencing where quakes start, how they spread, and why they stop. “Energy doesn’t build evenly along the fault,” Barbot said. “Some parts are more stressed, others closer to slipping.”

The quake also defied expectations by starting outside the “seismic gap”—a zone long thought overdue for rupture. Instead, it propagated through multiple sections, challenging assumptions about where major quakes originate. Researchers argue faults retain a “geological memory,” with past quakes leaving stress patterns that shape future events.

This insight suggests scientists must look beyond fault geometry to its stress history when assessing risk. Understanding this hidden complexity could improve hazard forecasts, treating faults as dynamic systems rather than static lines on maps.

The study was funded by the U.S. National Science Foundation, the Swiss National Science Foundation, and China’s Natural Science Foundation.