Burma is wedged between four tectonic plates; the Indian, Eurasian, Sunda and Burma plates that interact due to active geological processes. Along the west coast of the Coco Islands, off the Rahkine coast, and into Bangladesh, is a highly oblique convergent boundary known as the Sunda megathrust. This large fault marks the boundary between the Indian and Burma plates. The megathrust emerges from the seafloor in Bangladesh, where it runs parallel and east of the Chin Hills. This boundary continues to north of Burma where it ends at the eastern Himalayas.^[4]

The Sagaing Fault is a mostly continental transform fault that runs through Burma and connects the Andaman spreading center to the collision zone in the north. It accommodates motion between the Burma and Sunda Plates as they slide past each other at a rate of 18 to 49 mm/yr. The fault runs the entire length of the country for over 1,200 km and continues its trace into the Andaman Sea. The Sagaing Fault is Burma's largest and most active source of seismic threat, running through or close to major cities like Yangon, Nay Pyi Daw and Mandalay. Several large and damaging earthquakes have occurred on this fault in historical times.^[4]

The Sagaing Fault is a major transform boundary that runs through Myanmar, and is the source of the earthquake. The earthquake epicenter is presently located just outside the city of Mandalay. It is believed that the Meiktila and Sagaing segment of the fault ruptured during this earthquake for a length of 400 km (250 mi), generating an earthquake of magnitude 8.1–8.3 although further research is needed to confirm this.^[5] The basis for this claim is the overall lack of seismic activity in the Meiktila segment which runs from Nay Pyi Taw to Mandalay, a length of about 260 km (160 mi). There is no official magnitude presented for this earthquake but most news media and research journals put the figure at 7.0–7.5 or ≥8.0 M_w .^[6][7] Remote sensing and field observation revealed a maximum displacement of 5–7 m (16–23 ft) along the trace of the 1839 rupture just outside Mandalay. This would place the magnitude at 7.4–8.0+, and generate an earthquake rupture of at least 300 km (190 mi).^[8][9]

In 1946 the 180 km (110 mi) long Sagaing segment produced two major earthquakes but there are no records of its impact. Ten years later, in 1956, a magnitude 7.1 earthquake struck close to the city of Mandalay, re-rupturing the 1839 rupture zone for about 60 km (37 mi).^[10] Meanwhile, the 260 km long Meiktila segment has not experienced any major earthquake since 1839 and is considered a seismic gap.^[5]

The mainshock was preceded by a large foreshock in 1838 which also damaged the capital.^[11] Great damage was reported in Inwa, so severe that the formal capital was moved to nearby Amarapura. In Mingun, a stupa sustained serious damage as a result of shaking. British officials in Myanmar recorded catastrophic damage and liquefaction in Mandalay and the surrounding area.^[12][13] Many pagodas collapsed during the event. Chasms and fissures more than 10 ft (3.0 m) wide were seen in Amarapura and nearly every brick building was reduced to rubble. Some villages were swallowed up as a result of liquefaction.^[13] By a contemporary British estimate 300–400 people were killed.^[2] The shock also reversed the flow of the Irrawaddy River, where the currents became violent and overflowed its banks.^[12] It was felt for thousands of miles away from the epicenter, as far as Dacca, Calcutta and Bangkok.^[3]

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  Large cracks in the incomplete Mingun Pahtodawgyi caused by the earthquake
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  Nan Myint Tower slightly tilted due to ground effects from the tremor
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  The Mingun Bell resting on the ground after losing its supports to the quake, pictured in 1873
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  A plaque that stands beside the Mingun Bell
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  The Hsinbyume Pagoda in 2014. Extensive restoration was done by Mindon Min in 1874 after the earthquake.
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  The Maha Aungmye Bonzan Monastery after repair works
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  Preserved ruins from the ancient capital
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  Overgrown ruins of a stupa

• List of earthquakes in Myanmar
• List of historical earthquakes