Syhlet and nearby areas experienced a 4.5 magnitude earthquake this afternoon (9 September).
An official of the Bangladesh Meteorological Department told the media that the earthquake was detected at 4:18pm. The epicentre was located in Assam, India, over 263 kilometres away from the Dhaka Siesmic Centre, she added. No casualties or damage have been reported so far.
The greater Sylhet region bears high risk of devastating destruction if earthquake strikes obove 6 magnitudes in Richter scale, experts warn.
Several geological surveys show that among the risk of destructions over 75,000 infrastructure, including residential and commercial buildings face the hazard.
The survey also reveals that over 95 percent of the old buildings face such calamity as none of the buildings followed building codes in constructing infrastructures.
Sylhet region has resources like natural gas underground around the whole areas and being extorted the risk of earthquak is even greater as seismic waves may also produce explosions.
A number of geological surveys mentioned that Sylhet region is on high seismic alert zone among the other parts the country as the region lies along the hilly areas of the Indian border and the Dawki Fault, which is responsible for a number of devastating quakes for over a century. Many owners of the buildings are not cooperating with the Sylhet city corporation authority and not submitting the construction documents of their establishments when they were asked to submit the documents
A geological survey ‘Sedimentation and Tectonics of the Sylhet Trough’ as part of the geological survey of Bangladesh conducted jointly by Samuel Y Johnson and Abu Md Nur Alam published under USGS in 1990 mentioned that the inferred rates of horizontal displacement on the Dawki fault range from 5.6 to 16 Millimeter per year (28 to 80 km over 5 million 27 years).
Another study under Shahjalal University of Science and Technology (SUST) showed that the transition between Sylhet trough and the Shillong Plateau is represented by the Dawki fault system with huge vertical displacements.
It finds that the Shillong plateau has a thrust plane underneath it and is enduring a southward thrusting, which disproves the concept of vertical tectonism along the Dawki fault with a notably high seismic status.
The study also found that most of the buildings of Sylhet city are non-engineered, poorly designed and are of poor quality. It demonstrated that an earthquake greater than magnitude 7 will result a fatal human causality and economic loss due to the collapse of a large number of buildings in this region which may be estimated to 59 percents of buildings damage and 7 percents fatalities at night in the city similar to the 1918 Srimangal earthquake.
Considering regional seismicity, seismic history and seismic risk for Sylhet region, proper measures need to be taken and buildings should be designed and constructed in this area following building codes to have minimum safeguard of properties and life.
