What Seismologists Are Learning from the Myanmar Earthquake

When a major earthquake strikes, scientists usually spend months piecing together what happened. The Myanmar earthquake did not take that long to raise alarms. Almost immediately, researchers noticed something unusual. The rupture did not stumble, stall, or fragment, as many large earthquakes do. Instead, it tore along the fault quickly and cleanly, covering an extraordinary distance in a short amount of time.

That behavior is rare, and it is exactly why seismologists in the United States started paying close attention. Not because Myanmar predicts California’s future, but because it showed what a long, mature strike-slip fault can do under the right conditions. And California has one of those, too.

What Actually Happened Beneath Myanmar

On March 28, 2025, a magnitude 7.7 earthquake ruptured Myanmar’s Sagaing Fault, a major right-lateral strike-slip fault that runs through the heart of the country. What made this quake stand out was not just its size, but how it unfolded.

Based on seismic recordings, satellite radar data, and optical imagery, scientists determined that the rupture extended roughly 460 to more than 500 kilometers along the fault. That is unusually long for an earthquake of this magnitude. Even more striking, parts of the rupture moved at speeds approaching five to six kilometers per second, fast enough to qualify as what scientists call supershear.