Bangladesh, too, at risk of earthquake

Thirteen areas of Bangladesh are at risk of earthquake because of tectonic faults with the three districts of the Chittagong Hill Tracts and the Jaintiapur upazila of Sylhet district at the most risk.

These earthquake-prone areas are located 100km away from Dhaka, but an earthquake of magnitude 7-8 on the Richter scale may result in a large-scale disaster in the capital.

A study conducted by a group of teachers from Dhaka University, Columbia University, USA revealed this information.

According to seismologists from Bangladesh, a huge jolt is likely to be felt in Dhaka city by an earthquake of magnitude 7-8 from a distance of 100-200 kilometres and that may damage weak buildings in the city.

Soil is soft and weak in the expanded or new residential areas of Dhaka. So, multi-stories buildings constructed on such soil violating building codes are likely to collapse in the impact of an intermediate earthquake while earthquake pose relatively less risk to one to three-storied buildings constructed on red soil.

Besides, collapse of buildings is responsible for 90 per cent of deaths during an earthquake.

Speaking to Prothom Alo, Bangladesh Open University vice chancellor professor Syed Humayun Akhter said there are 13 underground cracks tectonic faults and all of them lie at a far distance from Dhaka.

But, many buildings may collapse in Dhaka once an intermediate to strong earthquake hit Sylhet and the Chittagong Hill Tracts, and the Rana Plaza tragedy is the proof that building can collapse without a tremor, he added.

Syed Humayun Akhter further said unfortunately it is true that building codes and land form are not followed during the construction of most of the structures in Dhaka and that why an earthquake of less magnitude than the one hitting Turkey may cause more damage in Dhaka.

According to civil engineering department of the Bangladesh University of Engineering and Technology (BUET), there are 2.1 million buildings in Dhaka with 600,000 buildings are six-story high or above.

Following the Rana Plaza building collapse, experts from the BUET proposed to the Rajdhani Unnayan Kartripakkha (RAJUK) to prepare a list of buildings based of their resilient capacity during an earthquake.

They recommended buildings posing highest risk to quakes should be marked with red signs while buildings with mild risk with yellow and buildings resilient to earthquake should be marked with green sign. However, the RAJUK did not follow this recommendation.

Retrofitting or necessary arrangement was taken to reduce risk at garment factories amid the pressure from foreign buyers after the Rana Plaza building collapse in 2013.

However, no necessary arrangement was maintained in residential and other buildings to make people’s lives safe. As a result, buildings collapsed or tilted in Dhaka in the impact of a light to moderate tremor.

A joint study of BUET and Dhaka University’s history department showed a magnitude 8.7 earthquake hit the Indian state of Assam in 1897 and the epicenter was 250 kilometer away from Dhaka. At that time, there were 90,000 people and 100 concrete buildings only in Dhaka and 10 buildings including Ahsan Manzil were damaged in that quake.

Speaking to Prothom Alo, seismologist Mehedi Ahmed Ansary, a civil engineering department professor of BUET, said a big disaster is waiting unless construction of building stops on soft soil as well as by violating building codes in Dhaka.

A research by professor ASM Maksud Kamal of disaster science and management department of Dhaka University (DU) and pro-vice-chancellor (academic) showed 35 per cent of 305 sq-km of Dhaka lie on read soil and this area are compatible with constructing multi-storied building.

The remaining 65 per cent are consisted of muddy and sandy soil on the riverbank. New towns like Mohammad, Uttara and Purbachal also built on this type of soil and most of the housing project also built on soft soil. Besides, buildings on soft soil are at the risk of collapsing and tilting in the impact of magnitude 5-6 earthquake, according to the research.

“We must take lessons from the earthquake of Turkey,” professor Maksud Kamal told Prothom Alo.