As two consecutive tremors hit Nepal leaving over 3,700 people dead, earthquake experts in Dhaka apprehend that an
unprecedented human disaster may occur here and elsewhere in Bangladesh in case of a heavy tremor as Bangladesh is situated in a high risk zone.
Bangladesh is located near the three active faults - Madhupur, Dawki and Himalayan faults.
According to the experts, a powerful earthquake needs at least 100-150 years to be originated for a particular region and in that sense it is overdue for Bangladesh and parts of Assam, as 112 years have passed by since a heavy tremor from Dawki Fault hit the region.
So, Bangladesh is highly vulnerable to a powerful earthquake, they said.
Ruling out the possibility of occurring a 7.8 magnitude tremor (one that hit in Nepal) in Bangladesh, earthquake expert Prof Jamilur Reza Chowdhury said a 7-magnitude earthquake may originate from Madhupur and Dawki faults.
He said if an 8-9 magnitude of earthquake originates from Dawki fault, Dhaka will face an ‘intensity of VII’ on the Richter scale that may destroy a huge number of buildings and leave nearly 1 lakh people dead.
“The Madhupur fault located near Dhaka city is very active to generate a moderate to heavy earthquake. A big earthquake originated from the fault in 1885 (127 years ago). Now energy is being accumulated in this fault and small quakes are giving an indication of a bigger one,” said seismic expert Prof Dr Syed Humayun Akhter.
The Dhaka city may face a devastating earthquake anytime due to shifting of the present plate boundary to the Jamuna-Meghna river basin from east and rapid accumulation of seismic energy beneath the city.
“With the passage of time, the present plate boundary is shifting from east to west (Jamuna-Meghna river basin), which put Dhaka at risk of tremor,” he said.
Showing earthquake data, Prof Humayun said a 4.5 magnitude tremor originated from Madhupur fault beneath the Buriganga River on December 19 in 2001 while two more small quakes occurred from the fault in 2008 (epicentres - Manikganj and Mymensigh).
“That means Madhupur is an active fault. And when energy accumulation will reach a critical level, the energy will be released leading to a devastating quake from the fault that will critically affect Dhaka city,” said Dr Humayun, a professor of the Geology Department of Dhaka University.
Although Dhaka is less vulnerable to tremor than Sylhet and Chittagong, it will experience massive damage due to soft formation of soil if one moderate quake hit the capital city, Prof Jamilur Reza said.
“Unplanned urbanisation and construction of buildings filling up the low-lying areas and wetlands intensify the earthquake-risk for Dhaka city,” he added.
According to Rajuk, there are over 10,000 vulnerable buildings in Dhaka city that were constructed with faulty design or violating the National Building Code, which collectively intensify the risk of Dhaka city due to untold destruction resulting from an earthquake.
According to the seismic experts, a huge number of structures and buildings of Bangladesh, including Dhaka, Chittagong and Sylhet, will completely be destroyed if a moderate tremor hit the country.
A study conducted by the Comprehensive Disaster Management Programme (CDMP) of the Bangladesh government in 2010 revealed the doomsday scenario of tremor’s vulnerability and its possible consequences.
The study showed that some 78,323 buildings will be destroyed completely if a 6-magnitude earthquake shakes Dhaka, causing havoc throughout the densely populated capital city. In case of a 7.5-magnitude earthquake from Madhupur Fault, some 72,316 buildings will be damaged totally - while an estimated 53,166 will be partially destroyed. If an 8.5-magnitude tremor from the plate boundary of Fault-2 hits the region, some 238,164 buildings will be destroyed completely across the country.
There will be an economic loss of about US$ 1.1 billion resulting from only structural damage in case of a 7.5-magnitude earthquake from the Madhupur Fault. Economic loss due to damage of structures will be US$ 650 million and US$ 1.07 billion respectively in case of an 8-magnitude earthquake from the plate boundary-2 and in case of a 6-magnitude earthquake from under Dhaka city, the study says.
A 7.5-magnitude earthquake from the Madhupur Fault will generate a total of 30 million tonnes of debris, killing some 131,029 people instantly and injuring 32,948 others.
According to the study, at least 10 major hospitals, 90 schools in the capital will be destroyed completely and another 241 hospitals and clinics, 30 police stations and four fire stations partially in case of a 7.5-magnitude quake.