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The Independent
02-04-2025
- Science
- The Independent
Myanmar earthquake caused by rare type of superfast rupture, scientists say
The devastating magnitude 7.7 earthquake, which struck Myanmar on Friday, killing over 2,800 people and leaving thousands more injured, was caused by a rare 'supershear' rupture that moved fast and far, scientists say. With tremors felt hundreds of miles away as far as the Thai capital of Bangkok, the death toll from the quake continues to rise, with over 3,900 reported injured and about 270 missing. Many are feared trapped under collapsed buildings across Myanmar and dozens from the collapse of a high-rise building under construction in Thailand. Scientists say the geological fault which broke during the quake – the massive Sagaing fault between the Burma and Sunda tectonic plates – likely ruptured 'very fast' and as far as 400km (250miles) to trigger the quake. 'The earthquake occurred on the Sagaing Fault – the major tectonic structure that accommodates the northward motion of India and western Myanmar with respect to the rest of South East Asia,' said Ian Watkinson, seismologist from Royal Holloway, University of London. This fault passes from the Andaman Sea in the south to the very northern part of Myanmar and is 'very similar in scale, movement and seismicity' to the San Andreas Fault in California, Dr Watkinson said in a statement. 'The rupture propagated both north and south with a rupture velocity of about 3km (1.8miles) per second,' seismologist Frederik Tilmann from the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany, said in a LinkedIn post. 'Remarkably, the southward propagating rupture accelerates up to a speed of about 5kmps,' Dr Tilman said, indicating that the rupture was likely a 'supershear' rupture. In supershear quakes, scientists say the rupture underground travels faster than the seismic waves it produces. This tends to concentrate seismic energy before the rupture, causing greater damage at much greater distances compared to normal quakes. Such a rupture of the fault is 'the earthquake equivalent of a supersonic jet', he said. 'The supershear rupture leads to a strong radiation of seismic energy in the forward direction,' the seismologist explained. 'The magnitude 7.7 earthquake appears to have ruptured a 200km section of the Sagaing Fault, a major North-South fault that separates the India plate and the Sunda Plate,' said seismologist Brian Baptie from the British Geological Survey (BGS). Dr Baptie observed that the rupture propagated from North to South in just about a minute. This unusually fast movement of the tectonic plates may have 'exacerbated damage' seen in Myanmar and caused the drastic effects experienced in Bangkok over 1000km (620miles) away from the epicentre, Dr Tilman said. 'The earthquake resulted in intense ground shaking, with at least 2.8 million people in Myanmar exposed to severe or violent shaking, with most of the population in the region living in buildings that are constructed from timber and unreinforced brick masonry, and that are vulnerable to earthquake shaking,' Dr Baptie added. Satellite imagery in the coming days may confirm the theory, scientists say.
Observer
28-03-2025
- Climate
- Observer
Aftershocks likely after Myanmar quake
Myanmar should prepare for possible aftershocks following the powerful earthquake that struck the country on Friday, a German geophysicist said. "We assume that aftershocks will occur. This is a typical process," said Oliver Heidbach from the GFZ Helmholtz Centre for Geosciences in the eastern German city of Potsdam. GFZ scientists said a series of aftershocks with magnitudes of between 6 and 6.5 is possible in the coming hours or days, with the quakes decreasing in number and strength over time. Alternatively, there could be a second strong earthquake, they said. Heidbach warned that seismic waves generated by strong aftershocks could hit buildings that have already been damaged, making rescue work more difficult and dangerous. The GFZ estimated the magnitude of Friday's initial earthquake at 7.6, with the epicentre at a depth of around 20 kilometres, according to its preliminary analysis. The epicentre of Friday's earthquake was near the city of Mandalay in Myanmar, but the quake was also felt in Thailand and other countries. A second earthquake hit the area minutes later, measured at a magnitude of 6.4 by the United States Geological Survey. The epicentre of the first earthquake was located on a fault that absorbs the movement of the Indian tectonic plate, which straddles the equator, Heidbach explained. He said the area is hit by strong earthquakes roughly every 100 years. Heidbach said it was too early to assess the consequences of the earthquake. The quake was also felt in Thailand's capital Bangkok as well as in parts of China and India. There were no initial reports of injuries or deaths from those countries. Meanwhile, Myanmar's ruling military general on Friday invited 'any country' to provide help and donations following a major earthquake that killed 144 people, warning there would be more deaths and casualties. Min Aung Hlaing on state television said he had opened routes for international assistance and had accepted offers of help from India and the Southeast Asian bloc Asean. The Red Cross in Myanmar has reported devastating damage following strong earthquakes. The International Federation of Red Cross and Red Crescent Societies (IFRC) has spoken to staff in the affected region, according to the IFRC programme manager on the ground, Marie Manrique. There is great concern that dams on the Irrawaddy River may have been damaged and could break. According to Manrique, 18.5 million people live in the affected area near the city of Sagaing, where two quakes — of an estimated magnitude of 7.7 and 6.4 — were recorded. According to the Office of the United Nations High Commissioner for Refugees (UNHCR), around 1.6 million of the 3.5 million displaced people in Myanmar live in the region hit by the earthquake. "We are very concerned about the possible humanitarian consequences," said Manrique. "We expect a lot of people to be injured." — Agencies
