The Sagaing Fault triggered the March 28 Myanmar quake as it had accumulated a lot of energy: O P Mishra

The huge 7.7 Magnitude earthquake that shook Myanmar and Thailand on March 28, 2025, has already claimed over 1,000 lives with the toll expected to climb further in the coming days.

Buildings across both countries were destroyed. Other infrastructure such as bridges was also damaged.

Myanmar is no stranger to earthquakes as it is located in one of the most seismically active regions of the world. Down To Earth spoke to O P Mishra, Director of the National Center of Seismology, New Delhi, on what caused the deadly quake on Friday.

Rajat Ghai (RG): Why has this earthquake taken place?

O P Mishra (OPM): The Sagaing Fault is the main reason. It is more than 1,200 kilometres in length and about 100 kilometres in width. This present earthquake occurred on the Sagaing Fault where past quakes of magnitude 7 and above have happened.

A quake in 1956 was of magnitude 7.2. Another in 1946 was of magnitude 7.8. Also in 1946, a segment of this Fault was broken by a 7.9 magnitude quake. In 1991, a quake of magnitude 6.9 or almost 7 took place. The 1956 quake took place very near to the epicentre of the 2025 quake. In 1912, a quake happened just south of the 2025 quake’s epicentre.

Clearly, the Sagaing Fault triggered the earthquake because it has been accumulating a lot of seismic energy in its various parts.

The Friday quake caused a several kilometres-long rupture that propelled from the mainshock source to Bangkok in Thailand and Mandalay and Naypidaw in Myanmar, causing ground shaking, cracking and fracture in the surrounding areas of the source zones of Thailand and India.

This was also due to the geomorphological conditions. There was soil amplification as there are alluvial deposits. As the earthquake happened, the seismic wave got amplified and proceeded forward.

RG: What is the tectonic and seismological makeup of Myanmar like?

OPM:  Myanmar is located at a point where four tectonic or crustal plates meet: The Indian plate is moving north into the Eurasian plate. The latter also has a micro plate known as the Burma or Myanmar plate. The Indian plate meets the Indo-Burma ranges and then subducts or goes under the Burma plate.

To the east of the Sagaing Fault is the Sunda Plate. The Fault is the partitioning between the Myanmar plate and the Sunda plate. The  Sagaing Fault is a ’strike-slip’ fault, which means that the Indian and Sunda landmasses are moving horizontally against each other which releases a lot of energy. The basin of the Chindwin river has a lot of alluvial deposits. Whenever an earthquake happens, these act as a propeller of seismic waves.

RG: What about fault reactivation?

OPM: An earthquake of such magnitude has not taken place since the 1990s. So, in a way this is a reactivation of the Sagaing Fault.