Has an earthquake ever struck so close to Dhaka before?
If the earthquake had lasted just 5-7 seconds longer, the number of casualties and building collapses could have increased manifold, experts say
The epicentre of the earthquake that occurred at 10:38am this morning (21 November) was just 13 kilometres east of the Bangladesh Meteorological Department (BMD) headquarters in Dhaka's Agargaon.
This 5.7 magnitude earthquake, which originated in Narsingdi's Madhabdi, has already resulted in at least six deaths, including three in Old Dhaka, and over a hundred injuries.
Several hundred buildings in the capital have reportedly tilted.
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Earthquake experts say that an earthquake of this magnitude so close to Dhaka has never happened before. They also say that if the earthquake had lasted just 5-7 seconds longer, the number of casualties and building collapses could have increased manifold.
Speaking to The Business Standard, Md Momenul Islam, director (current charge) of BMD, said, "This earthquake's epicentre was very close to Dhaka, which is why it was felt so intensely.
"Even if an earthquake of magnitude 7 or higher occurs in Rangamati or Khagrachari, we don't feel such a strong jolt in Dhaka. However, if this earthquake had lasted just 5-7 seconds longer, many buildings in Dhaka would have collapsed. Dhaka and its surrounding areas have never before experienced an earthquake such as this."
Momenul, also a seismology researcher, added, "It may commonly seem that a magnitude 6 earthquake is just one point more than a magnitude 5. But that is not the case.
"A magnitude 6 earthquake has a vibrating tendency 10 times greater than a magnitude 5. Here, every fraction means its intensity is proportionally higher. Consequently, this earthquake's tendency has intensity over at least a 100-kilometre radius."
Dhaka's vulnerability
A 2024 study by the Rajdhani Unnayan Kartripakkha (Rajuk) warns that if a 6.9 magnitude earthquake strikes the Madhupur fault in Tangail, between 40.28% and 64.83% of Dhaka's buildings could collapse.
The estimated death toll would vary depending on the time of occurrence: 2.1 to 3.1 lakh lives in the morning, 2.7 to 4 lakh in the afternoon, and 3.2 to 5 lakh at night.
If a 7.1 magnitude earthquake hits along the Sylhet lineament, between 40,935 and 3.14 lakh buildings (1.91% to 14.66%) in Dhaka could suffer damage, according to the study.
Dhaka has over 21.5 lakh buildings under Rajuk's jurisdiction, including 5.14 lakh concrete structures. Of the 3,252 buildings surveyed, 42 were identified as high-risk and recommended for demolition.
In terms of financial impact, earthquake experts estimated losses exceeding $1 billion in transportation, $887 million in water and wastewater systems, and $27.1 million in electricity infrastructure.
Several risk factors
Experts highlight several risk factors for Dhaka's vulnerability. The city, one of the most densely populated in the world, is packed with poorly constructed high-rises, slums, and narrow streets.
Many buildings fail to meet seismic safety standards, turning them into potential death traps. Additionally, much of Bangladesh is built on loose, waterlogged sediment, which can liquefy during strong tremors, leading to building collapses.
Unlike earthquake-prone regions such as Japan or California, Bangladesh lacks widespread public awareness, emergency drills, and an efficient disaster response system, warn experts.
Historically, the region has witnessed devastating quakes. The 1897 Great Indian Earthquake (8.0 magnitude) claimed over 1,500 lives in then-undivided Bengal, while the 1918 Srimangal Earthquake (7.6 magnitude) caused extensive damage.
72,000 buildings could collapse
Among the earthquakes with epicentres in or around Dhaka in the past were a 4.5 magnitude quake on 18 March 2012, a 4.8 magnitude quake on 26 July 2008, and a 4.5 magnitude quake on 19 December 2001.
However, these incidents did not result in major casualties.
Additionally, a 6.2 magnitude earthquake occurred in Chattogram on 26 November 2011, among recent events.
According to a survey by the Comprehensive Disaster Management Programme (CDMP), a 7.5 magnitude earthquake would collapse 72,000 buildings and severely damage another 1.5 lakh buildings.
Especially, many old buildings built on weak soil and buildings taller than six stories constructed without adhering to the building code would be the primary victims.
