AFTER a 7.7 magnitude earthquake in Myanmar and an 8.2 magnitude earthquake in Thailand on March 28, Bangladesh also felt a 4.5 magnitude tremor. The earthquake started only 597 km from Dhaka, raising concerns about earthquake risks in Bangladesh. Experts warn that the energy stored in the Indo-Burma Subduction Zone and the Dauki Fault could be released anytime, causing a major earthquake in the country.
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100-year seismic cycle
IN 1918, an 8.0 magnitude earthquake hit the Bangladesh region, killing 150,000 people. According to geologists, major earthquakes tend to happen every 100 years in the same area. Bangladesh has already passed this time frame in 2023. The number of small earthquakes has also increased significantly. According to the Bangladesh Meteorological Department, there were 28 earthquakes in 2017, 41 in 2023, and 54 in 2024.
According to the Seismic Gap Theory, small earthquakes release some of the stress in the earth鈥檚 crust, reducing the risk of a big earthquake. For example, in California鈥檚 San Andreas Fault, small quakes have reduced the risk of a 6.0+ magnitude earthquake by 15-20 per cent. However, Bangladesh is different. A 2022 study from Dhaka University found that the Dauki Fault is storing energy at a rate of 1.6 cm per year. However, earthquakes smaller than 4.0 magnitude release only 0.01 per cent of this energy. To prevent a major earthquake (7.5+ magnitude), therefore, the energy must be released over 200 years, which is not possible.
A report from the USGS shows that before Japan鈥檚 Tohoku earthquake (2011) and California鈥檚 Ridgecrest earthquake (2019), there were 20+ and 300+ small tremors recorded, respectively. In Bangladesh, the locked segment of the Indo-Burma zone has not had a major earthquake in 500 years, meaning that an 8.0+ magnitude earthquake could happen. A 2023 study in Seismological Research Letters states that the probability of a major earthquake in this region increases by 23 per cent every decade.
The Gutenberg-Richter law states that for every 1,000 earthquakes of 3.0 magnitude, one earthquake of 6.0+ magnitude occurs. But in Bangladesh, the number of 3.0+ magnitude quakes in 2023 was 35 per cent higher than the average (Journal of Seismology, 2023). According to a 2021 study in Nature Communications, the Indo-Burma Zone stores 3.5 metres of energy annually, which small earthquakes cannot release. A recent study from the University of Tokyo warns that the probability of an 8.0+ magnitude earthquake in Bangladesh is increasing by 2 per cent every year.
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Bangladesh鈥檚 major earthquake zones
Northeast (Dauki fault): According to the Journal of South Asian Studies (1998), this 300 km long reverse fault caused the 1897 Great Assam Earthquake (8.7 magnitude), leading to soil liquefaction and over 200 deaths in Sylhet. Currently, there is a 30 per cent chance of a 7.5+ magnitude earthquake here.
Southeast (Indo-Burma subduction zone): The Indian Plate is moving under the Burma Plate at a rate of 46 mm per year. A magnitude 8.2-8.5 earthquake could cause a 9-metre-high tsunami, destroying Cox鈥檚 Bazar and Chattogram coasts.
Central (Dhaka-Narayanganj): According to Rajuk, 82 per cent of buildings in Dhaka are not earthquake-resistant. The geology department of Bangladesh University of Engineering warns that a 6.0 magnitude earthquake could turn the Buriganga鈥檚 soft soil into liquid, causing 70 per cent of buildings to collapse.
Coastal (Sunderbans-St Martins): There is a risk of a tsunami similar to the 2004 disaster due to submarine faults and fractures beneath the coral reefs.
Risk in Dhaka: An international organisation, GIG-Japan (2023), has warned that a 7.0 magnitude earthquake in Dhaka could collapse 72,000 buildings and kill 21 million people. Explosions from gas and electricity lines, broken water pipelines, and collapsed flyovers could make rescue efforts difficult. The Fire Service and Civil Defence report that it took 7 days to rescue people from one collapsed building at Savar. If 72,000 buildings collapse, the situation will be unimaginable.
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Only way out
WE CANNOT stop earthquakes, but we can prepare for them. According to the Tonankai Model from Japan (Bulletin of the Seismological Society of America, 2018), the probability of an 8.0+ magnitude earthquake in the Indo-Burma zone increases by 1.5 per cent every year. Dhaka must enforce strict building codes, raise awareness, and create emergency plans. Remember鈥攅arthquakes do not kill people, but weak buildings and lack of preparation do.
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Arghya Protik Chowdhury is a student of environmental science at Bangladesh University of Professionals.