1839 Ava earthquake

1839 Ava earthquake

1839 Ava earthquake (Southeast Asia)
UTC time	1839-03-23 24:30
Local date	23 March 1839
Local time	04:00
Magnitude	7.9–8.3 Mw
Epicenter	21°54′N 96°00′E / 21.9°N 96.0°E / 21.9; 96.0
Fault	Sagaing Fault
Areas affected	Konbaung dynasty (present–day Myanmar)
Max. intensity	MMI XI (Extreme)
Foreshocks	Yes
Aftershocks	Yes
Casualties	300–400 dead

The 1839 Ava earthquake, also known as the Amarapura earthquake or Inwa earthquake, was a disastrous seismic event that struck present-day central Myanmar on March 23.

Myanmar 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.^[3]

The

The Meiktila and Sagaing segment of the fault ruptured during this earthquake for a length of 400 km (250 mi), corresponding to a magnitude 8.1–8.3 earthquake, although little research has been conducted to provide further constrains.^[5] On the basis for its overall lack of seismic activity, the Meiktila segment is believed to have ruptured during the earthquake. This segment runs from Nay Pyi Taw to Mandalay, a length of about 260 km (160 mi).^[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 a ~300 km (190 mi) rupture.^[8][9]

Researchers at National Taiwan University combined lidar and macroseismic data from historic accounts to estimate its magnitude at ~M_w  7.9 and rupture length to be 285–325 km (177–202 mi). The 1839 earthquake ruptured two segments; the Meiktila segment in the south and Sagaing segment in the north. They estimated 5.5 m (18 ft) of displacement on the Sagaing segment while slip on the Meiktila segment was around 3.8 m (12 ft). The felt area based on the Modified Mercalli intensity was larger than the 1912 Maymyo earthquake (M_w  7.7) and similar in area to the 2002 Denali earthquake (M_w  7.9). The maximum assigned Modified Mercalli intensity was XI (Extreme).^[10]

Damage and effects

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, about 300–400 people died.^[1] 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 Dhaka, Kolkata and Bangkok.^[2]

Gallery

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

See also

• List of earthquakes in Myanmar
• List of historical earthquakes

References