2025 Sagaing earthquake

2025 Myanmar earthquake

File:Earthquake Damage Mandalay, 2025.png Earthquake damage in Mandalay
Mandalay Naypyidaw Yangon Bangkok Chiang Mai
UTC time	2025-03-28 06:20:54
ISC event	643071319
USGS-ANSS	ComCat
Local date	28 March 2025 (2025-03-28)
Local time	12:50:54 MMT (UTC+6:30)
Magnitude	Mw 7.7
Depth	10 km (6 mi)
Epicenter	22.013°N 95.922°E / 22.013; 95.922
Fault	Sagaing Fault
Type	Strike-slip
Areas affected	Myanmar, Thailand, Southwestern China
Max. intensity	IX (Violent)
Aftershocks	77+ recorded Strongest: Mww 6.7
Casualties	1,661+ fatalities, 3,478+ injuries, 218+ missing

On 28 March 2025 (INC: 07 Saura Chaitra 1947) at 12:50:54 MMT (06:20:54 UTC), a M_w (magnitude) 7.7 earthquake occurred in the Sagaing Region of Myanmar, near Mandalay, the country's second-largest city. The earthquake, characterized by strike-slip faulting, reached a maximum Modified Mercalli intensity of IX (Violent). This event marked the most powerful earthquake to hit Myanmar since the 1912 Maymyo earthquake, which had a magnitude of 7.9. The quake resulted in substantial damage across Myanmar and also affected neighboring Thailand.

The earthquake resulted in over 1,600 fatalities in Myanmar and 10 in Thailand, with more than 2,400 individuals reported injured. Additionally, hundreds were missing, including at a collapsed construction site in Bangkok. The city's shallow geology makes it particularly susceptible to seismic waves from distant earthquakes, compounded by a lack of awareness regarding seismic risks, which heightened its vulnerability to earthquake-related consequences. As of 28 March, authorities declared a state of emergency, anticipating an increase in the death toll. The ongoing civil war in Myanmar has further complicated disaster relief efforts. This earthquake was the deadliest to impact the country since the 1930 Bago earthquake.

tectonic setting

Myanmar is situated at the convergence of four tectonic plates: the Indian, Eurasian, Sunda, and Burma plates, which interact due to active geological processes. Along the west coast of the Coco Islands, extending off the Rakhine coast into Bangladesh, lies a highly oblique convergent boundary known as the Sunda megathrust. This significant fault delineates the boundary between the Indian and Burma plates and emerges from the seafloor in Bangladesh, running parallel and east of the Chin Hills. The boundary continues northward through Myanmar, terminating at the eastern Himalayas.

A 1,400-kilometer transform fault known as the Sagaing Fault traverses Myanmar, linking the Andaman spreading center to a collision zone in the north. This fault serves as the boundary between the Burma and Sunda plates, which slide past each other at a rate of 18–49 mm (0.71–1.93 in) per year. It is the largest and most active source of earthquakes in Myanmar, passing through or near major cities such as Yangon, Naypyidaw, and Mandalay. Significant and destructive earthquakes along the Sagaing Fault have occurred in May and December 1930 (Ms 7.3 & 7.5), 1931 (Ms 7.5), 1946 (Mw 7.3 & 7.7), 1956 (Ms 7.0), 1991 (Mw 6.9), and 2012 (Mw 6.9). Earthquake magnitudes along the Sagaing Fault range from Mw 7.0 to 8.0, with recurrence intervals varying by location along the fault. The southern segments, which ruptured in 1930, have return periods estimated at 100–150 years based on paleoseismological studies.

Destructive earthquakes have impacted Myanmar for centuries, but academic research on these events has been limited. Consequently, many earthquakes in the region, including significant surface-rupturing events, remain poorly understood. One notable event was a large Mw 8.5–8.8 earthquake in 1762, which ruptured a segment of the Sunda megathrust off the Rakhine coast. This earthquake is believed to have resulted from the Indian plate subducting beneath the Burma plate along the megathrust. Additionally, remnants of the subducted Indian plate beneath central Myanmar can trigger intraslab earthquakes, such as the 1975 Bagan earthquake, which was caused by reverse faulting within the Indian plate at an intermediate depth of 120 km (75 mi).

The earthquake also had repercussions in Thailand, particularly affecting the Bangkok region, located approximately 1,000 kilometers from the epicenter. The geology of Bangkok, characterized by a top layer of soft marine clay, makes its high-rises susceptible to distant, powerful earthquakes. The pervasive clay layer amplifies long-period ground motion, potentially matching the resonant frequency of tall buildings as they sway. As a result, occupants in Bangkok have frequently experienced effects from earthquakes occurring hundreds or even thousands of kilometers away. Research led by Pennung Warnitchai from the Asian Institute of Technology previously identified the Sagaing Fault as a significant risk factor, particularly if a magnitude-8.0 earthquake were to occur in the Andaman Sea, just 400 km from the city, posing a threat of future disaster. To mitigate catastrophic impacts on skyscrapers, basic seismic considerations were only incorporated into the building code in 2007, leaving older structures particularly vulnerable.

A study published in the Journal of Geophysical Research: Solid Earth indicates that the Sagaing Fault can be categorized into two main regions: the northern and southern sections. The southern section of the Sagaing Fault, located between 16.5 and 23.5 degrees north latitude, is further divided into five segments from south to north: the Bago, Pyu, Naypyidaw, Meiktila, and Sagaing segments.

The Naypyidaw segment is notable for its two parallel faults that extend for 70 km, with portions situated beneath the capital city, Naypyidaw. The last recorded earthquake in this segment occurred in 1929, with a magnitude less than 7.0. The Meiktila segment, which spans 220 km between Mandalay and Naypyidaw, is characterized as a linear feature. The nearly flat topography across this segment suggests that the slip component is entirely horizontal. Although it has not experienced any major earthquakes, it may have ruptured during the 1839 Ava earthquake.

The Sagaing segment runs parallel to the Ayeyarwady River and is also a linear feature. The northern portion of this segment ruptured during one of the main shocks of the 1946 Sagaing earthquakes, while the 1956 Sagaing earthquake affected the southern strand of this segment. This segmentation of the Sagaing Fault highlights the complexity and potential seismic hazards associated with this active fault system.