More than half of Dhaka and its surrounding areas are highly vulnerable to soil liquefaction during a major earthquake.
A recent assessment found that approximately 55-60 per cent of the 1,528 square kilometres under RAJUK's jurisdiction is composed of liquefaction-prone soil, significantly increasing the risk of widespread structural damage and catastrophic losses during a strong seismic event.
A recent study by the Rajdhani Unnayan Kartripakkha (RAJUK) and the Bangladesh University of Engineering and Technology (BUET) has found that nearly 55 to 60 per cent of Dhaka falls within high-risk earthquake zones. Experts say the findings should serve as a wake-up call for policymakers, developers and city residents alike.
Why Dhaka is vulnerable
Bangladesh has experienced several earthquakes in recent months.
On June 7, a magnitude-5.6 earthquake with its epicentre in Bhutan was felt in Dhaka and other parts of the country. The epicentre was located about 432 kilometres north of the Bangladesh Meteorological Department's Seismic Centre in Agargaon.
Earlier, on May 26, a magnitude-3.4 earthquake struck with its epicentre in Bhaluka, Mymensingh, and was felt in various parts of the country, including the capital.
Before that, on April 21, a magnitude-5.1 earthquake originating near Homalin in Myanmar's Sagaing Region caused mild tremors in Dhaka, with residents reporting light shaking for a few seconds.
Unlike many cities built on stable bedrock, large parts of Dhaka have expanded over wetlands, floodplains and reclaimed land. These areas contain loose sand, soft clay and water-saturated soil, making them highly susceptible to soil liquefaction temporarily loses its strength during strong shaking.
When liquefaction occurs, buildings can sink, tilt or collapse even if their foundations remain intact.
According to BUET Professor Mehedi Ahmed Ansary, liquefaction is only one part of the problem. Soft soil also amplifies seismic waves, causing stronger ground shaking than would occur on harder ground.
The most vulnerable areas
BUET's Liquefaction Potential Index (LPI) categorizes Dhaka's soil into four risk levels red, magenta, blue and green.
Red zone is the highest risk areas of Bangladesh. Hazratpur, Savar, Keraniganj, Narayanganj, Tegharia, Konda, Enayetnagar, Kashipur, Kalagachia, Narayanganj Municipality, Bandar, Mograpara, Narayanganj Sadar, Bakhtabali, parts of Mohammadpur and Dhanmondi, New Market, Lalbagh, Madanpur, Dumni, Badda, parts of Pathalia, Ashulia, Kataballi and Darus Salam are in the red zone.
Magenta region is the medium to high risk area. This includes Konabari, Yarpur, parts of Harirampur, Biralia, different municipal areas, Cantonment, Pallabi, Gulshan, Rupganj, Bhulta, Khilgaon, Kafrul and parts of Dakshinkhan, Adabor, Tejgaon, Rampura, Motijheel, Demra, Sabujbagh, Jatrabari, Kadamtali, Kadam Rasul Municipality, Musapur, Fatullah and parts of Hazaribagh, Sadipur, Kanchpur and Paltan.
The red zones represent the highest level of danger and could experience severe ground failure during a magnitude-7.5 earthquake, particularly near rivers, canals and other areas with high groundwater levels.
The Bangladesh National Building Code (BNBC) requires site-specific soil investigations, proper piling and ground improvement before construction in weak-soil areas. However, many projects skip the costly process of soil improvement. Instead, developers often install deep piles without strengthening the surrounding soil.
Professor Ansary estimates that nearly 90 per cent of Dhaka's filled land has not undergone adequate soil treatment, leaving structures vulnerable to severe damage during major earthquakes.
He points to international examples, including the 2001 Kandla earthquake in India, where a building supported by deep piles still tilted because the surrounding waterlogged soil failed.
Advanced Engineering can reduce the risk
Engineers insist that weak soil does not mean construction is impossible.
Modern engineering techniques including soil compaction, cement injection, stone columns and ground stabilization can significantly improve the strength of sandy soil and reduce earthquake damage. Improving only the upper five to six metres of weak soil can substantially lower seismic risks in many locations.
Former Bangladesh Urban Resilience Programme Project Director Abdul Latif Helali said a soft-soil hazard map has already been prepared but has yet to be incorporated into RAJUK's planning framework.
RAJUK says the map will be considered during the next revision of the Detailed Area Plan (DAP), though experts argue that implementation should not be delayed.
What needs to be done
Specialists say reducing earthquake risk requires coordinated action rather than isolated engineering solutions.
Priority measures include strict enforcement of the BNBC, mandatory geotechnical investigations before construction, soil improvement in high-risk areas, stronger monitoring of building practices and integrating hazard maps into urban planning.
Public awareness, emergency preparedness and regular earthquake drills are also essential for reducing casualties.
A race against time
Dhaka cannot prevent earthquakes, but experts say it can reduce their consequences.
As the capital continues to grow vertically and horizontally, the decisions made today about where and how buildings are constructed will determine whether a future earthquake becomes a manageable emergency or a national catastrophe.
The science is already available. The challenge now is ensuring that planning, construction and enforcement keep pace before nature exposes the city's vulnerabilities.
