Experts say Friday's devastating earthquake in Myanmar is the strongest in decades for the country and thousands may have died.
Myanmar's ruling junta said Saturday morning that the death toll had topped 1,000 and more than 2,000 were injured. However, the U.S. Geological Survey analysis says there is a 35 percent chance the possible death toll could be in the 10,000-100,000 range. The service warned that the financial damage could exceed Myanmar's GDP. Weak infrastructure will complicate relief efforts in the isolated, military-ruled country, where emergency services and a health system have already been devastated by four years of civil war sparked by a military coup in 2021.
A dangerous mistake
Bill McGuire, emeritus professor of geophysical and climatic hazards at University College London (UCL), said it was "probably the biggest earthquake in mainland Myanmar for three-quarters of a century". A 6.7-magnitude aftershock struck minutes after the first and McGuire warned that "more could be expected".
Rebecca Bell, a tectonics expert at Imperial College London (ICL), suggested it was a lateral "slip" of the Sagaing fault. This is where the Indian tectonic plate to the west meets the Sunda plate, which forms much of Southeast Asia - a fault similar in scale and movement to the San Andreas fault in California. "The Sagaing fault is very long, 1,200 kilometers, and very straight," Bell said. "The straight nature means earthquakes can rupture large areas - and the larger the area of the fault that slips, the larger the earthquake."
Earthquakes in such cases can be "particularly destructive," Bell added. Because the earthquake occurred at a shallow depth, its seismic energy dissipated little by the time it reached the Earth's surface. That causes "a lot of surface shaking," Bell said.
Construction boom
Myanmar has been hit by powerful earthquakes in the past. There have been more than 14 earthquakes of magnitude 6 or more in the past century, including a 6.8-magnitude quake near Mandalay in 1956, said Brian Bapti, a seismologist with the British Geological Survey. Ian Watkinson, of the department of earth sciences at Royal Holloway University of London, said what has changed in recent decades is "the boom in tall buildings constructed of reinforced concrete." Myanmar has been torn by years of conflict and has a low level of building design enforcement.
"Critically, during all previous earthquakes of magnitude 7 or greater on the Sagaing fault, Myanmar was relatively undeveloped, with mostly low-rise timber-framed buildings and brick religious monuments. Today's earthquake is the first test of Myanmar's modern infrastructure against a large, shallow-focus quake near its major cities," Watkinson said
Bapti said at least 2.8 million people in Myanmar are in heavily affected areas, where most live in buildings "made of timber and brickwork" that are vulnerable to earthquake shaking. "The usual mantra is that 'earthquakes don't kill people; collapsing infrastructure does. Governments are responsible for planning regulations and building codes. The disaster reveals what the Burma/Myanmar governments failed to do long before the quake, which would have saved lives during the shaking", said Ilan Kelman, a disaster reduction expert.
Skyscraper checks
Strong tremors also shook neighboring Thailand, where a 30-story skyscraper under construction was turned into a pile of dusty concrete, trapping workers in the rubble. Expert Christian Malaga-Chukitape of Imperial College London explained that the nature of the ground in Bangkok contributed to the impact on the city, despite being about 1,000 kilometres from the epicentre in Myanmar. "Although Bangkok is far from active faults, its soft ground amplifies the shaking. This particularly affects tall buildings during distant earthquakes." Malaga-Chuckitape said construction techniques in Bangkok favour "flat slabs" where floors are held up by columns alone, without the use of bracing beams, and resemble a table supported only by legs. | BGNES, AFP
