On March 28, 2025, a big, bad earthquake slammed into Myanmar, estimated between a moment magnitude of 7.7 and 7.8. This preventable catastrophe killed at least 5,352 individuals. In addition to loss of human life, it resulted in crushing structural devastation across the region. The earthquake’s surface rupture extended more than 450 kilometers, damaging both major cities such as Mandalay and Naypyidaw. In fact, it instantly became one of the longest—and fastest-moving—ruptures ever recorded on land.
This earthquake struck along the Sagaing Fault, which is identified as a major tectonic boundary in Myanmar. Early modeling indicates that the rupture initiated as a bilateral subshear. From there it shifted into a supershear velocity—about 5.3 kilometers per second—just over 100 kilometers south of the epicenter. Almost a third of the fault was moved at this extraordinary supershear velocity, over 200 kilometers, a rare testament to the super special geological stuff going on down there.
Shengji Wei and his fellow researchers have a detailed analysis of the data from this seismic event. Most recently they’ve identified the key ingredients that give rise to the impressive behavior of supershear ruptures. Perhaps one of the biggest surprises is the scale of the impact of a thick sedimentary basin’s influence. This basin, up to 3 kilometers wide, runs parallel to the southernmost portion of the fault. This basin likely played a crucial role in sustaining the supershear rupture by allowing reflective waves from its bottom to increase shear stress on the fault, thereby promoting further rupture propagation.
The broader implications of this study go far beyond Myanmar. The 2025 earthquake offers a unique glimpse into the future. These results have the potential to improve hazard analyses for other large strike-slip faults, such as California’s San Andreas Fault and Turkey’s North Anatolian Fault. By understanding the conditions that lead to supershear ruptures, scientists can better predict potential seismic activity and mitigate risks associated with such powerful earthquakes.
The earthquake’s impacts were felt much farther afield across the entire region. Residents in Bangkok, Thailand, reported feeling the shaking almost 1,000 kilometers away from the epicenter. This wide-reaching impact underscores the importance of ongoing research into seismic activity and the necessity for improved preparedness in regions susceptible to similar geological events.