Catastrophic M7.7 earthquake caused by rupture of Sagaing Fault in Myanmar
Limited reporting thus far from Myanmar, but this is a big one
Judith A Hubbard and Kyle Bradley
We note that both of us have spent time in Myanmar looking at some of the faults and related features described below. Our deepest sympathies are with the people of Myanmar, and with the scientists of Myanmar with whom we have interacted, many of whom have spent their careers trying to understand this fault and the hazards it poses.
At 12:50 PM local time on March 28, 2025, a ~M7.7 earthquake ruptured an ~200-km-long section of the Sagaing Fault in Myanmar. The rupture started just west of the city of Mandalay, Myanmar’s second most populous city. It is likely that up to ~5 meters of slip occurred on the fault, which ruptured over about ninety seconds. The earthquake was followed eleven minutes later by a M6.4 aftershock. A number of other aftershocks have occurred since then, all smaller than M5 so far.
(Note that Burma is another name for Myanmar; we use the second option to identify the country, but recognize the complex issues at hand.)
Although we want to get into the potential impacts, we should probably start with an overview of the region. Here follows a map of the busy seismic world of Myanmar.
Sandwiched between India and southeastern Eurasia, this entire region is a major tectonic collision zone. The fault that ruptured today is called the Sagaing Fault, and is a huge strike-slip fault that reaches from the coast in the south all the way to Myanmar’s northern border, a distance of almost 1,200 kilometers. This region is extremely complicated from a tectonic perspective. Put very simply, the India Plate is shouldering its way northward as it collides with Eurasia. Along its the eastern edge, it is dragging along a sliver-like fragment of the crust and mantle, causing strike-slip faulting on the Sagaing Fault. (As pointed out by a reader, that sliver is appropriately called the Burma Plate).
The Sagaing Fault has long been considered one of the most dangerous strike-slip faults on Earth, because it passes directly by Yangon (the largest city), Nay Pyi Taw (the capital), and — most closely — Mandalay, the second largest city.
Read more: https://earthquakeinsights.substack.com/p/catastrophic-m77-earthquake-caused
