A powerful earthquake struck Myanmar on March 28, 2025, along the Sagaing Fault, providing rare insights into how ancient faults release energy. Researchers found that the event transferred seismic motion fully to the surface, challenging previous models of shallow slip deficits. This discovery has implications for faults like California's San Andreas.
The earthquake on March 28, 2025, ruptured along the Sagaing Fault in Myanmar, a strike-slip system comparable to California's San Andreas. This fault, described as mature due to millions of years of smooth horizontal motion, allowed for an unusually straight and continuous 500-kilometer rupture. To put that in perspective, the crack spanned a distance akin to from Albuquerque to Denver, with ground sides sliding past each other by 10 to 15 feet.
An international team led by Eric Lindsey, an assistant professor at the University of New Mexico, analyzed the event using satellite data since on-site access was limited by conflict and damage. They employed Sentinel-2 for optical image correlation, tracking pixel shifts in pre- and post-quake photos, and Sentinel-1 for InSAR, which detects ground changes down to fractions of an inch via radar signals. "By comparing the time it takes for the signal to bounce back to the satellite from each point on the ground, we can detect changes in the ground's elevation or position down to a fraction of an inch," Lindsey explained.
The study, published in Nature Communications under the title "Mature fault mechanics revealed by the highly efficient 2025 Mandalay earthquake," addressed the longstanding shallow slip deficit. In this quake, deep underground motion was fully transferred to the surface, unlike many events where surface movement is reduced. "We found that in the 2025 Mandalay earthquake, this deficit was non-existent," Lindsey noted. "The massive amount of slip that happened miles underground was transferred 100% to the surface."
The rupture linked multiple fault segments, slipping less in areas last active in the 20th century and more in those dormant since the 1800s, demonstrating slip predictability. Lindsey highlighted the fault's smoothness: "Because it is so smooth and straight, the earthquake rupture could travel very efficiently across a huge distance."
These findings suggest that on mature faults, shaking near the surface could be more intense than current hazard models predict, informing better preparedness for similar systems worldwide. The research underscores satellite technology's role in studying hazards in inaccessible regions, with applications even for monitoring New Mexico's Rio Grande Rift.
