How did the Myanmar earthquake occur? | Explained

Devastating earthquake in Myanmar reveals tectonic complexities, historical patterns, and potential risks for South Asia.

The story so far:

The powerful earthquake in Myanmar on March 28 had its source in central Myanmar, about 20 km from Mandalay, the country’s second-largest city. Mandalay, located on the east bank of the Irrawaddy river, is close to one of the most seismically active faults in the region, called the Sagaing fault, named after a town not far from Mandalay on the river’s opposite side. The earthquake of magnitude 7.7 struck around 12:50 pm local time, followed by several strong aftershocks, including one of magnitude 6.4, which occurred 11 minutes after the major event.

The quakes were very devastating: they affected the entire region, left thousands of people dead, and destroyed many homes. The damage zone extended to Bangkok, the capital of neighbouring Thailand, which is about 1,000 km from the earthquake’s epicentre.

However, the damage in Bangkok was minimal, confined to the complete collapse of a 33-storey high-rise under construction, and causing water from a swimming pool on the top of another high-rise building to overflow. However, these incidents were given much hype because of the city’s place on the global tourism circuit. The outpouring of water from the rooftop pool was due to seismic seiches — oscillations in the water triggered by the passage of seismic waves through the area. Even though the building was located far from the earthquake’s source, slower, long-period seismic waves can cause the top floors to sway more and amplify the seiches, as observed in this case.

Editorial | Lessons from a quake: on the Myanmar earthquake 

The damage prediction models of the U.S. Geological Survey estimated that the total death toll in the region could reach well over 10,000. Mandalay itself is home to over 1.5 million people and was hit the hardest, with many buildings, including pagodas, mosques, and bridges, either partially damaged or completely collapsed. A review of the damage pattern reveals that much of the devastation was concentrated in the southern areas of the Sagaing fault because this region is sitting on a thicker pile of alluvium, deposited by the Irrawaddy, which amplifies the seismic energy, as compared to the northern parts of the fault. This also explains why China’s southwest Yunnan Province, which is north of the fault, escaped earthquake-induced damage. The depth to the source of the 2025 earthquake on the Sagaing fault was only 10 km, which is another contributing factor for the heavy damage and a large felt area (area where the earthquake’s shaking is felt).

The neighbouring eastern parts of India also escaped damage because the energy released by the earthquake dispersed in a north-south direction, following the trend of the fault.