Why Were Myanmar, Thailand Earthquakes So Devastating and What Caused Them?

With an epicentre near Mandalay in Myanmar, a powerful earthquake with a magnitude of 7.7 jolted major parts of Southeast Asia on Friday. Followed by an aftershock of 6.4 magnitude, the earthquake flattened multiple buildings and killed over 140 people in India’s neighbouring country and Thailand’s capital Bangkok where the collapse of a high-rise under construction claimed the lives of at least eight labourers. Authorities in both nations declared a state of emergency as rescue teams continue to search for survivors beneath the rubble.

What caused the earthquakes?

While earthquakes in Southeast Asia are common, seldom are they intense so much so that cities are levelled and lives taken. The ones that brought Myanmar and major Thai cities such as Bangkok — a key tourism hub — to a standstill appear to have originated from the region along the Sagaing Fault, an important tectonic boundary where the Burma microplate slides past the Sunda Plate at a rate of 18-49mm per year. Sagaing’s is a strike-strip fault where tectonic plates move horizontally, causing impactful disturbances such as earthquakes and tsunamis.

Myanmar’s location lies at the intersection of four tectonic plates — Indian, Eurasian, Sunda, and Burma, making it one of the most seismically active regions in the world. The shifting of complex tectonic plates in this region creates immense pressure in the Earth’s crust, resulting in frequent earthquakes, some with high magnitudes. In this case, both the primary earthquake and the aftershock were triggered by the shifting of these tectonic plates from the faulting at a shallow depth of roughly 10 kilometres.

Why were the earthquakes so devastating?

The earthquake’s high magnitude, further amplified by the aftershock, is measured to be critically dangerous on the Richter Scale. It can cause widespread damage and loss of life. Add to that the shallow depth of the origin, vulnerable concrete structures, and population density of the areas in Myanmar and Thailand. Other factors such as soil amplification at the Chao Phraya River basin in Bangkok intensified the shaking, causing buildings, some of which were weak, to collapse. The death of people has mostly been attributed to the falling of buildings and other structures.

“Myanmar is no stranger to earthquakes. The plate boundary between the India Plate and Eurasia Plate runs approximately north-south, cutting through the middle of the country. These two plates move past each other as they are moving at different rates along a transform plate boundary (a bit like the San Andreas Fault in the southwest of the United States),” said Joanna Faure Walker, Professor of Earthquake Geology and Disaster Risk Reduction, University College London (UCL). “Although such strike-slip earthquakes are of smaller magnitude than the largest earthquakes seen in subduction zones, like to the south in Sumatra, they can still reach magnitudes 7 to 8 and cause severe destruction, as we are seeing in the March 2025 earthquake.”

Myanmar’s socio-economic challenges and a high population density in the Thai capital hindered immediate relief efforts, leading to an increase in the death toll.

A similarly-destructive earthquake crippled Nepal in 2015, killing nearly 9,000 people and injuring over 21,000 people across the Himalayan country, India, Bhutan, China, and Bangladesh .

Read more: Be Prepared for Next Emergency: How to Detect Earthquakes Using Phones