Dhaka has long expanded faster than it has planned. Wetlands have been filled, low-lying areas built over, and high-rises have been raised that may not withstand a major earthquake. In the fifth instalment of a six-part series, Star examines how poor construction, weak enforcement of building codes, and inadequate retrofitting have left thousands of buildings prone to collapse during major quakes.

A large number of buildings across Bangladesh -- particularly older ones -- were not designed to withstand earthquakes, as they were constructed without fully complying with the Bangladesh National Building Code (BNBC), experts warned.

They said poor reinforcement, weak beam-column connections, and substandard construction practices have left many buildings highly vulnerable.

When seismic shaking begins, these weak points are often the first to fail, causing partial or complete collapse.

A Rajdhani Unnayan Kartripakkha (Rajuk) study under the World Bank-funded Urban Resilience Project estimates that a magnitude-6.9 earthquake along the Madhupur Fault in Tangail could damage nearly 8,65,000 buildings in Dhaka. If the quake occurs during busy daytime hours, it could kill nearly 2,10,000 people and injure another 2,29,000.

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According to the Comprehensive Disaster Management Programme, implemented by the Ministry of Food and Disaster Management between 2004 and 2014, Bangladesh lies close to five major fault zones -- Madhupur Fault, Dauki Fault, and Plate Boundary Faults 1, 2, and 3 -- capable of generating earthquakes ranging from magnitude 7.0 to 8.5.

Despite such alarming projections, earthquake preparedness in Dhaka remains grossly inadequate, experts said, blaming unplanned urbanisation, weak enforcement of building regulations, and widespread construction on filled wetlands for increasing the vulnerability.

“The message is simple: everyone must strictly follow the existing building regulations. In the past, enforcement was weak,” said Prof Munaz Ahmed Noor, vice-president of Bangladesh Earthquake Society.

“Rajuk is supposed to scrutinise building designs before approving them, but that oversight is often lacking. Bangladesh should follow countries such as Malaysia, Thailand and Indonesia, where independent third-party verification of structural designs is mandatory before approval,” he said.

According to Rajuk, around 2.1 million buildings stand within its 1,528-square-kilometre jurisdiction, about 84 percent of them single-storey.

Another concern is the addition of rooftop loads beyond a building’s original design capacity.

Heavy water tanks, generators and mechanical equipment add significant weight and create concentrated loads, increasing structural movement during earthquakes, said Ahmed Mukta, managing director of Architectural Consultancy LLC.

“In already weak structures, these additional loads can push buildings beyond their limits, turning a manageable situation into a major hazard,” he said.

Ahmed, a veteran architect, said earthquake injuries are often caused not by structural collapse but by the failure of non-structural elements.

“Partition walls, false ceilings, glass façades and exterior cladding often fail first. Falling debris, loose materials, and shattered glass can cause serious injuries even when the main structure remains intact.”

He said studies worldwide show similar patterns. Brick walls built with poor-quality mortar often fail quickly. Soft-storey buildings -- those with open ground floors -- perform poorly during earthquakes, while inadequate foundations can lead to tilting or settlement during shaking.

“Unfortunately, many of these construction flaws are common in Bangladesh.”

He stressed the need to raise public awareness about earthquake, fire, and disaster safety so people can take preventive measures before disasters strike.

Echoing similar concerns, Prof Mehedi Ahmed Ansary of Buet’s Civil Engineering Department said, “Earthquakes do not kill people -- poorly constructed buildings do.”

He cited the 2023 magnitude-7.8 Türkiye earthquake, where nearly 53,500 people died largely because of building collapses.

Similarly, while Haiti’s magnitude-7.0 earthquake in 2010 killed about 230,000 people due to widespread structural failure, Chile’s much stronger magnitude-8.8 earthquake that same year caused only about 280 deaths despite releasing nearly 800 times more energy.

To reduce the impact of future earthquakes, Prof Ansary proposed assessing existing buildings and classifying them into three categories -- red (highly vulnerable), yellow (moderately vulnerable), and green (relatively safe).

He said such classification would help authorities prioritise retrofitting while enabling banks to finance strengthening work based on proper technical documentation.

“This approach has already been successfully applied in retrofitting nearly 500 garment factories over the past decade under the Ministry of Labour.”

He also said independent engineering firms must monitor retrofitting throughout the process.

Although around 100 engineering consultancy firms in Bangladesh currently have the capacity to undertake such work, he said the number must increase through structured training and professional mentoring.

Architect Ahmed Mukta recommended several measures to reduce earthquake risk, including adding reinforced masonry walls to open parking floors, securely connecting masonry walls to structural frames, installing automatic seismic shut-off systems for gas and electricity, and strengthening façades by anchoring brickwork to columns and beams with appropriate connectors.

For households, he advised anchoring heavy furniture to walls, using rubber pads beneath appliances to prevent sliding, applying safety film to glass surfaces, and identifying safe shelter locations in every room.

For workplaces, he stressed the importance of knowing designated safe zones, evacuation routes and assembly points; keeping corridors and exits unobstructed; securing shelves and equipment; avoiding heavy objects on high shelves; participating in earthquake drills; and reporting unsafe structural or electrical conditions.

Residents should also know the locations of gas, water and electricity shut-off valves, ensure they are clearly labelled, and shut off utilities immediately if leaks, sparks or visible damage are detected after an earthquake, he added.

Ahmed noted that many multi-storey buildings have open parking levels without adequate bracing walls, allowing excessive movement of upper floors during earthquakes.

“Strategically placed bracing walls can significantly reduce cracking and structural damage. Steel buildings benefit from diagonal bracing, while reinforced concrete structures require properly positioned shear walls,” he said.

Overall, he said a three-phase strategy comprising risk assessment, preventive measures and rescue preparedness could significantly reduce earthquake risks.

“Even where enforcement remains weak, sustained public awareness campaigns can encourage wider adoption of earthquake-resistant construction and safety practices.”

He also recommended avoiding rooftop water tanks wherever feasible, suggesting underground reservoirs with pneumatic pumping systems instead to eliminate additional dynamic loads.

Elevated swimming pools should likewise be carefully monitored and equipped with automatic release valves to reduce seismic risk, he added.

Rajuk Chief Town Planner Ashraful Islam said around 300 vulnerable buildings were identified in Dhaka following the recent Narsingdi earthquake.

“The survey was mainly area-based, identifying buildings that suffered damage or appeared vulnerable. These structures should undergo detailed structural evaluation, particularly those built after 2008 or without proper approval,” he said.

Older buildings should also be thoroughly assessed and categorised according to their structural condition.

“Without comprehensive structural assessments, these buildings could trigger a major disaster at any time,” he said.