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2025 Sagaing earthquake
 | This article is about a current disaster where information can change quickly or be unreliable. The latest page updates may not reflect the most up-to-date information. |
 Earthquake damage in Mandalay | |
| UTC time | 2025-03-28 06:20:54 |
|---|---|
| ISC event | 643071319 |
| USGS-ANSS | ComCat |
| Local date | 28 March 2025 |
| Local time | 12:50:54 MMT (UTC+6:30) |
| Magnitude | Mw 7.7 |
| Depth | 10 km (6 mi) |
| Epicenter | 22°00′47″N 95°55′19″E / 22.013°N 95.922°ECoordinates: 22°00′47″N 95°55′19″E / 22.013°N 95.922°E |
| Fault | Sagaing Fault |
| Type | Strike-slip |
| Areas affected | Myanmar, Thailand, Southwestern China |
| Max. intensity | IX (Violent) |
| Aftershocks | 77+ recorded Strongest: Mww 6.7[1] |
| 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 Mw (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[edit]
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.
Earthquake[edit]
The earthquake occurred at 12:50 MMT, with its epicenter located near Mandalay, specifically in the Sagaing–Mandalay border region. According to the United States Geological Survey (USGS), it measured 7.7 on the moment magnitude scale, while the Thai Meteorological Department reported a magnitude of 8.2. The Institut de Physique du Globe de Paris estimated the earthquake's moment magnitude at 7.9.
This event is noted as the largest earthquake with an epicenter in Myanmar since the 1912 Maymyo earthquake, which also had a moment magnitude of 7.9. The focal mechanism solution suggested that the earthquake resulted from strike-slip faulting at a depth of 10 km, a type of faulting consistent with rupture along the Sagaing Fault. A finite fault model released by the USGS indicated that the earthquake rupture extended approximately 350 km by 10 km, stretching from Thabeikkyin in Mandalay to Naypyidaw. Of this rupture, 100 km occurred north of the epicenter, while 250 km ruptured to the south.
Most of the slip, exceeding 1 m (3 ft 3 in), was concentrated between Thabeikkyin and Yamethin, north of Naypyidaw. The maximum slip recorded was 6.48 m (21.3 ft), situated north of the hypocenter between Singu and Madaya. However, ShakeMap parameters suggest that the rupture may have extended as far as Zin Chaung town to the north and Htantabin to the south, potentially making it nearly 500 km long. Following the mainshock, more than 70 aftershocks were recorded, with the largest measuring Mww 6.7 occurring just 12 minutes later.
A study conducted by Nobuo Hurukawa and Phyo Maung Maung, published in Geophysical Research Letters, identified two seismic gaps along the Sagaing Fault. One of these gaps is situated in central Myanmar, specifically between 19.2 degrees north and 21.5 degrees north, which corresponds to the Meiktila segment. The researchers concluded that this 260 km gap has the potential to generate a magnitude 7.9 earthquake if it experiences a complete rupture.
Both the Meiktila and the northern Sagaing segment are believed to have been sources of the 1839 Ava earthquake, which likely ruptured between 285 and 325 km of fault across these segments. An analysis of the seismic intensity distribution suggests that the estimated magnitude of the 1839 event was also around 7.9. Seismologists Judith Hubbard and Kyle Bradley indicated that this seismic gap exists between the ruptures from the 1929 Naypyidaw segment and the 1956 southern Sagaing segment. They proposed that the 1839 earthquake may have partially ruptured this seismic gap based on their evaluation of the preliminary finite fault model released by the USGS.
The rupture extent analyzed corresponds with both the Meiktila and Sagaing segments, overlapping with the rupture area of the 1839 earthquake. Additionally, the fault extent involved in the Mw 7.1 earthquake of 1956 appears to have been affected during the recent event on March 28, 2025. The researchers estimated that the rupture from the March 28 event terminates to the north just south of the rupture associated with the 2012 Shwebo earthquake, which occurred on the central Sagaing segment. This analysis underscores the seismic risks posed by the gaps along the Sagaing Fault and their potential for significant future earthquakes.