It's time to wake up | The Daily Star
12:00 AM, May 16, 2015 / LAST MODIFIED: 12:56 AM, May 20, 2015

Experts say it’s time to wake up as Dhaka city highly vulnerable to earthquake hazards due to unplanned urbanisation

Unplanned urbanisation leaves Dhaka city vulnerable to catastrophic damage in strong earthquake, say experts

Unplanned urban development and housing settlement on filled up marshland and low-lying flood flow zones have made the capital highly vulnerable to earthquake hazards, said leading seismic experts.

They feared an earthquake above 7 magnitude on the Richter scale would result in colossal loss of life and properties in the city.

“A major earthquake is at the door of Bangladesh ... the country's geological position, tectonic setup and seismic historical facts are indicative of such an impending disaster,” said Prof Syed Humayun Akhter, chairman of the geology department at Dhaka University and a noted seismologist.  

“So, what we urgently need are public awareness and the government's preparedness,” he said.

When two tectonic plates get locked with each other, energy accumulates inside the earth for over hundreds of years. The energy is released through the borderline or fault line of the tectonic plates resulting in earthquake, added the DU teacher. 

Bangladesh lies close to three tectonic plates, including the Indian plate to the west and south west, Tibet sub-plate to the north and Burmese sub-plate to the east. The plates have converging or transverse movements, said Prof Akhter.    

“More importantly, borderline of the Indian plate and Burmese sub-plate runs across Bangladesh territory and the strain energy is building up along the plate boundary that will result in an earthquake,” he noted.

That aside, there are active fault lines of the plates like Modhupur and a fault line stretching from Mymensingh to Faridpur across Dhaka and Dauki fault line along the foot of Shilong plateau in Bangladesh-Meghalaya border.       

There are also the main boundary thrust of Indian plate and Eurasia plate at the foot of the Himalaya to the north of Bangladesh, Chittagong-Arakan plate boundary to the east, Sylhet-Assam plate boundary fault to the north-east of Dhaka, Kaladan fault of Burma plate in Mizoram and Burma.

“These are all considered potential sources of major and great earthquakes with the magnitude above 7 on the Richter scale,” mentioned Prof Akhter.

Over the last four centuries, a 7 magnitude Modhupur earthquake in 1885 and the 1897 great Indian earthquake with 8.7 magnitude in Assam rocked and damaged Bangladesh. The Dauki great earthquake in 1787 changed the course of the Brahmaputra, he said.

The Sylhet-Assam fault triggered a 7.6 magnitude earthquake in 1918 while Srimangal experienced a 7.5 magnitude earthquake in 1868, he said, adding that the 8.5 magnitude earthquake along the Chittagong-Arakan plate boundary in 1762 raised the Saint Martin's Island by two and a half metres, making it habitable.   

Energy has been building up at all the above said borderlines and faults and it would be released causing an earthquake, said the expert.

According to him, the 7.8 magnitude Pokhara earthquake in Nepal on April 25 is a recurrence after 80 years. It has so far claimed over 7,800 lives and ruined hundreds of structures.   

VULNERABILITY

ASM Maksud Kamal, chairman of the department of disaster science and management at Dhaka University, said over 1.40 lakh one to four-storey masonry buildings (built without iron rods) out of around four lakh buildings in 300 sqkm area of Dhaka city might collapse in the event of an 7.5 magnitude earthquake within the Bangladesh territory.

Besides, at least 80,000 buildings with a soft storey (which is less stiff) or the ground floor vacant for car parking are equally vulnerable, he added, citing the findings of the Comprehensive Disaster Management Programme (CDMP).

The over-hanging buildings with heavier top floors than the bottom would collapse first, said Maksud, who led the CDMP earthquake technical team.    

“The structures built on the earth-filled low-lying marshland stand extremely vulnerable to earthquakes, as the ground shaking wave duration is longer in marshland than what it is in strong red soil,” he noted.

Of the 300 square-kilometre area of the core Dhaka city, 65 percent is of soft soil.

Any 7.5 magnitude earthquake along the 60km-long Modhupur fault line or 240km-long Dauki fault line, both within Bangladesh territory, would result in such a havoc.      

Mehedi Ahmed Ansary, professor of civil engineering at Buet and the founding general secretary of Bangladesh Earthquake Society, echoed the views of Prof Akhter.

Citing examples of building collapses like Rana Plaza, Phoenix and Spectrum without an earthquake, Mehedi warned about the dangers of constructing buildings without regulatory oversight and flouting the National Building Code. Those three disasters exposed the country's inability to tackle a single building collapse.

He said the Assam earthquake in 1897, with the epicentre 250km off Dhaka, had killed 1,542 people in Dhaka, which had a population of just 90,000 back then, and razed half the masonry structures across the 20 sqkm city.

The human catastrophe in the event of a major earthquake is foreseeable with the population now 100 times bigger and the city area expanded manifold due to an unplanned growth.

The Bashundhara Housing Project, Pallabi and Goran schemes of Eastern Housing, Niketan housing, Baridhara DOHS, Aftabnagar housing, Jolshiri housing for the army and settlements on the Buriganga flood plains were all made by filling low-lying marshland and flood flow zones. This was done without any scientific oversight, making the structures there potentially vulnerable to earthquakes, he said.

Such filling is going on a massive scale in the 1,528 sqkm area of Rajdhani Unnayan Kartripakkha.

Brig Gen Ali Ahmed Khan, director general of Fire Service and Civil Defence, said gas explosion, fire from electricity and water contamination following an earthquake would take the situation out of their control.

“The roads may be inaccessible with rubble of collapsed buildings. The chemical warehouses and factories in residential areas might cause infernos…. The first aid medical teams may not be able to reach the victims,” he mentioned.     

There is no designated water reservoir in Dhaka city to fight any major fire, Khan pointed out. 

PREPAREDNESS

The fire service DG said there are 30,000 trained volunteers, 200 trained officials and 57 sets of rescue and search equipment, like cutting tools and drilling hammers. The army has some heavy equipment like concrete breakers and excavators.

“But such preparedness is extremely inadequate to manage the devastation of a major earthquake,” he added.

Prof Maksud Kamal said of the 2,300km roads in 127 sqkm city corporations area, only 300km are accessible by fire service rescue vehicles and heavy equipment. Though a contingency plan involving 13 government organisations is in place for post-earthquake disaster management, it lacks coordination and preparedness, he noted.

Also, there is no trained manpower to operate all the available equipment. 

The experts stressed the need for launching a massive campaign to make people aware of simple life saving tips during an earthquake.

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