The story thus far:
The highly effective earthquake in Myanmar on March 28 had its supply in central Myanmar, about 20 km from Mandalay, the nation’s second-largest metropolis. Mandalay, situated on the east financial institution of the Irrawaddy river, is near one in every of the most seismically energetic faults in the area, referred to as the Sagaing fault, named after a city not removed from Mandalay on the river’s reverse aspect. The earthquake of magnitude 7.7 struck round 12:50 pm native time, adopted by a number of sturdy aftershocks, together with one in every of magnitude 6.4, which occurred 11 minutes after the main occasion.
Also learn | Myanmar earthquake demise toll rises to three,085
What impact did the earthquakes have?
The quakes have been very devastating: they affected the total area, left 1000’s of individuals lifeless, and destroyed many houses. The injury zone prolonged to Bangkok, the capital of neighbouring Thailand, which is about 1,000 km from the earthquake’s epicentre.
However, the injury in Bangkok was minimal, confined to the full collapse of a 33-storey high-rise below development, and inflicting water from a swimming pool on the high of one other high-rise constructing to overflow. However, these incidents got a lot hype due to the metropolis’s place on the world tourism circuit. The outpouring of water from the rooftop pool was as a result of seismic seiches — oscillations in the water triggered by the passage of seismic waves by means of the space. Even although the constructing was situated removed from the earthquake’s supply, slower, long-period seismic waves may cause the high flooring to sway extra and amplify the seiches, as noticed on this case.
Editorial | Lessons from a quake: on the Myanmar earthquake
The injury prediction fashions of the U.S. Geological Survey estimated that the whole demise toll in the area might attain nicely over 10,000. Mandalay itself is house to over 1.5 million individuals and was hit the hardest, with many buildings, together with pagodas, mosques, and bridges, both partially broken or utterly collapsed. A evaluate of the injury sample reveals that a lot of the devastation was concentrated in the southern areas of the Sagaing fault as a result of this area is sitting on a thicker pile of alluvium, deposited by the Irrawaddy, which amplifies the seismic power, as in comparison with the northern components of the fault. This additionally explains why China’s southwest Yunnan Province, which is north of the fault, escaped earthquake-induced injury. The depth to the supply of the 2025 earthquake on the Sagaing fault was solely 10 km, which is one other contributing issue for the heavy injury and a big felt space (space the place the earthquake’s shaking is felt).
The neighbouring jap components of India additionally escaped injury as a result of the power launched by the earthquake dispersed in a north-south route, following the pattern of the fault.
Are quakes frequent in South Asia?
South Asia, together with Myanmar, is extremely vulnerable to earthquakes as a result of its proximity to the advanced assemblage of a few of the largest tectonic options on earth, together with the Himalayas, the Shillong Plateau, the Southern Indo-Burman Range, and the Andaman-Nicobar subduction zone. Originating from the collision of the Indian and the Eurasian Plates some 40 million years in the past, the plate boundary in Southeast Asia is an energetic tectonic characteristic that generated one in every of the largest earthquakes in historical past, of magnitude 9.2, and a transcontinental tsunami in 2004.
The tectonic stress accumulating on these plate boundaries is the reason behind frequent seismic exercise in the area. The earthquake of 1792 was additionally an important ‘megathrust’ earthquake of magnitude 8.5, with its epicentre situated someplace alongside the Arakan coast of Myanmar. This seismic occasion generated a tsunami in the northern Bay of Bengal and brought on widespread soil liquefaction in the Chittagong areas of Bangladesh. The massive thrust fault extends additional north onto the Chittagong-Tripura fold belt, the place a number of average earthquakes proceed to happen. It remains to be not clear whether or not this a part of the deformation entrance can generate future nice earthquakes.
Southeast Asia is a tectonic museum that displays constructions that host earthquakes of various faulting mechanisms, occurring at depths starting from as shallow as 5 km to 200-400 km. The deeper ones happen in the southern areas nearer to Indonesia or the Indo-Burmese areas in the north, bordering the subduction entrance alongside the Indo-Eurasian plates. The 2025 Mandalay earthquake in Central Myanmar was sourced from inside the continental a part of the mountain vary. In the tectonics of mountain constructing, such options develop when sediment piles up and rocks are scraped off from the subducting Indian plate, which get plastered onto the overriding Asian plate.
What is the geodynamic context of the Sagaing fault?
Because of the advanced interaction of plate motions and the ensuing geodynamics in the jap margin of the Indian Ocean, the northeast-directed convergence of the India and Eurasia plates takes place in a slanted trend reasonably than occurring head-on. This indirect convergence of the plates causes the total pressure to grow to be partitioned, with a part of the deformation being perpendicular to the plate boundary and the different half occurring parallel inside the interiors. The north-south working Sagaing fault varieties the tectonic boundary between the Central Myanmar Lowlands and the Indo-Burman Range. An elongated micro-tectonic block that exists between the Indian plate and the Sagaing fault is usually referred to as the Burma plate or the Burma sliver. It owes its origin to the pressure partitioning occurring at the subduction entrance.
Studies have revealed that this fault, with its subsidiary parallel constructions, accommodates a lot of the strike-slip a part of the indirect convergence, with a slip charge of 15-25 mm a yr and an gathered slippage of 100-700 km. The Sagaing fault accommodates about 50-55% of the total plate movement in the area. Unlike the vertical motions of fault blocks alongside the frontal a part of the convergence zone, the place one tectonic block is pushed up on the different, the motion is horizontal on the Sagaing fault, with the blocks sliding previous one another. The San Andreas fault in the western U.S. is one other such instance. Unlike thrust faults, the place earthquakes originate at both shallow or deeper sources, earthquakes on strike-slip faults are nearly all the time shallower (10-15 km).
Classified as a typical ridge-trench rework fault, the Sagaing fault system runs 1,400 km between the spreading centre below the Andaman Sea in the south to the jap Himalayan bend in the north. It has an extended historical past of earthquakes. Moderate and occasional sturdy earthquakes of magnitudes 7 and above are frequent in central Myanmar, the place six sturdy quakes of seven.0 magnitude or extra struck between 1930 and 1956 alongside the Sagaing fault or on adjoining constructions. Analyses of historic earthquakes have revealed that about half of the Sagaing fault has ruptured in the previous couple of a long time. Thus, the 2025 earthquake shouldn’t be a shock occasion however part of the earthquakes occurring sequentially on this construction to launch the accumulating stresses from the ongoing energetic plate interactions.
What does the Mandalay earthquake portend?
Historical information assist the incidence of an earthquake in 1839, referred to as the Ava earthquake, that killed greater than 500 individuals in central Myanmar. This occasion could have originated on one in every of the segments of the Sagaing fault with a hypothesised magnitude of seven.8. Equally attention-grabbing is the earthquake of 1927, reportedly felt strongly north of Yangon, Myanmar’s largest metropolis with a present inhabitants of greater than 4 million individuals. Records additionally point out that an earthquake occurred in 1946, probably on the Sagaing fault north of Mandalay and with a magnitude of seven.7, like that of the 2025 temblor.
The historic metropolis of Bagan in Central Myanmar, densely full of non secular monuments, has additionally been subjected to a number of damaging earthquakes. The newest one to hit this city was in 2016.
Science helps us perceive the processes behind earthquakes and gives approximate areas of future earthquakes and their doable magnitudes. The Sagaing fault shouldn’t be merely a scientific curiosity: it has a tragic affect on the thousands and thousands who stay with the stressed fault beneath their ft. Myanmar is struggling to deal with the aftermath of the newest earthquake, with a rising demise toll and intensive injury to infrastructure, each sophisticated by the ongoing civil conflict.
The 2025 Mandalay earthquake ought to function a warning to India. As the nation most vulnerable to earthquakes in South Asia, India ought to introduce scientifically examined security measures and procedures to mitigate the affect of earthquakes.
C.P. Rajendran is an adjunct professor at the National Institute of Advanced Studies, Bengaluru. This article benefited from the paper by Yu Wang et al., revealed in JGR Solid Earth on March 15, 2014.
Published – April 03, 2025 08:30 am IST
