Has an earthquake this intense 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
Highlights:
- Experts say Dhaka rarely experiences tremor this close
- Seconds more shaking could have caused major collapse
- BMD notes proximity drives intensity of yesterday's quake
- Historical quakes show region's long seismic record
- Study warns up to 65% of Dhaka buildings at risk
The 5.7-magnitude earthquake that struck yesterday morning originated in Narsingdi's Madhabdi – a location close enough to Dhaka to cause severe shaking across the capital.
Earthquake experts say Dhaka has rarely experienced such strong shaking from such a nearby epicentre.
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They noted that if the tremor had continued for just a few seconds longer, the scale of casualties and building damage could have increased significantly.
Speaking to The Business Standard, Md Momenul Islam, director (current charge) of the Bangladesh Meteorological Department (BMD), said the intensity felt in Dhaka was directly linked to the proximity of the epicentre.
"This earthquake's epicentre was very close to Dhaka, which is why it was felt so intensely," he said.
"Even if an earthquake of magnitude 7 or higher occurs in Rangamati or Khagrachhari, we do not feel such a strong jolt in Dhaka. However, if this earthquake had lasted just five to seven seconds longer, many buildings in Dhaka would have collapsed."
Past quakes in the region
Historically, the region has experienced devastating earthquakes. The 1897 Great Indian Earthquake (8.0 magnitude) killed more than 1,500 people in then-undivided Bengal, while the 1918 Srimangal Earthquake (7.6 magnitude) caused extensive damage.
Past earthquakes with epicentres in or around Dhaka include 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. None caused major casualties.
A 6.2 magnitude earthquake struck Chattogram on 26 November 2011 among recent events.
BMD's Momenul Islam, also a seismology researcher, added that the apparent difference between magnitudes can be misleading.
"It may commonly seem that a magnitude 6 earthquake is just one point higher than a magnitude 5. But that is not the case," he said.
"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," he added.
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.
Older buildings on weak soil and high-rises above six storeys constructed without adherence to the building code would face the greatest risk.
Rubaiyat Kabir, head of BMD's Earthquake Monitoring and Research Centre, explained that Bangladesh is situated in a geologically complex and highly earthquake-prone area.
He noted that the country sits on the Indian Plate, bordered by the Eurasian Plate to the north and the Myanmar Plate to the east.
This complex setting is further compounded by the presence of the major Dauki Fault above the country and the Sagaing Fault in Myanmar.
"And earthquakes happen in this region quite often. Earthquakes [like today's earthquake] do not happen in this region often," he said, adding, "Even considering the repeat time of earthquakes, there is a possibility of a major earthquake occurring in this region."
Dhaka's vulnerability
Experts highlight several risk factors behind 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 depend on the time of day: 2.1-3.1 lakh deaths in the morning, 2.7-4 lakh in the afternoon, and 3.2-5 lakh at night.
If a 7.1 magnitude earthquake occurs along the Sylhet lineament, between 40,935 and 3.14 lakh buildings (1.91% to 14.66%) in Dhaka could be damaged.
Dhaka has more than 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, experts estimate losses of over $1 billion in the transport sector, $887 million in water and wastewater systems, and $27.1 million in electricity infrastructure.
The city, one of the world's most densely populated, is filled with poorly constructed high-rises, slums and narrow streets.
Many buildings fail to meet seismic safety standards, making them potential hazards. Much of Bangladesh also sits on loose, waterlogged sediment that can liquefy during strong tremors, causing structures to collapse.
Unlike highly earthquake-prone regions such as Japan or California, Bangladesh lacks widespread public awareness, regular emergency drills and an efficient disaster response system, according to experts.
