Authorities begin identifying faulty buildings in Sylhet city 10 days after multiple tremors
People die in earthquakes when they are trapped inside a building constructed through flouting of rules and do not know what to do during a quake.
Earthquakes affect faulty buildings. Such buildings develop cracks or tilt or collapse when struck by a strong tremor. Thus no one can blame earthquakes for the massive loss of lives and property caused.
The Sylhet authorities have taken some initiatives following three quakes and several aftershocks that have jolted the city since late May. Among the initiatives have been the shutdown of 25 risky residential buildings and shopping centres, and the launch of a survey on Thursday to identify other buildings at risk.
But earthquakes are not new for people in the Sylhet region.
The epicentres of most of the 36 earthquakes of magnitude 5 and above on the Richter Scale that have struck Sylhet region since 1918 were in places within 50km of the district town – Netrakona, Sunamganj, Habiganj, and Maulvibazar. Sylhet lies along the hilly areas of the Indian border.
Sylhet is located near the Dawki Fault, which is responsible for a number of devastating quakes for over a century, and most of the epicentres were near the city, according to the United States Geological Survey (USGS), which records earthquakes across the world.
The last major earthquake of magnitude 5.5 with the epicentre in Maulvibazar, only 42km from Sylhet, hit the city on March 2, 2013.
The strongest tremors felt in the Sylhet area in the last 100 years were a 7.2 quake in 1918 and a 6 in 1997.
Last year, two earthquakes hit Sylhet city – a magnitude 4.2 tremor on June 3 and a 4.5 one on January 27.
On May 29 this year, the first tremor struck at 10:36am with a magnitude of 3 on the Richter scale, followed by the aftershocks of a 4.1-magnitude at 10:50am, 2.8-magnitude at 11:30am, and 4-magnitude at 1:58pm, according to the Bangladesh Meteorological Department (BMD).
At 4:35am the next day, another earthquake of magnitude 2.8 was felt in the city.
Most recently, on June 7, a magnitude 3.8 tremor shook the city at 6:30pm. A man, who was on the roof of a high-rise building of the city, said he felt that the building was swaying in the air. Many people came out on the streets at the time.
Earthquakes don't kill, buildings do
Frightened by recurrent quakes, many residents of high-rise buildings have left the city for their village homes.
However, those buildings did not collapse or develop cracks due to the three quakes and the aftershocks.
It is the old and small vulnerable buildings that were partially affected. Two six-storey buildings tilted after the May 29 quake while a school building was declared abandoned after the latest mild tremor.
Experts say the recurrence of low-magnitude earthquakes is a precursor to high-magnitude tremors.
In 2009, the government announced that 24,000 out of the 52,000 buildings surveyed in Sylhet town were at risk from earthquakes.
This result emerged from a survey conducted in Dhaka, Chittagong and Sylhet cities in 2008-09 under the Comprehensive Disaster Management Program (CDMP) project under the Ministry of Disaster Management and Relief.
At the time, experts suggested demolition or retrofitting of risky buildings to avoid loss of lives and a massive economic loss.
They also highlighted the need for preparing maps of utility connections, training of staff at hospitals, purchase of sophisticated equipment for the fire service, and preparing volunteers as first responders during a disaster.
Even though the Dhaka city authorities took some steps in this regard, no preparedness measures were taken by the Sylhet authorities to prevent losses. The existing vulnerable buildings were not retrofitted while the new high-rise buildings were erected without making them earthquake resistant.
Construction and earthquake experts say it does not cost much to make buildings that can resist strong tremors. On the other hand, retrofitting old buildings increases their life span by 100 years.
Due to the negligence of the authorities concerned, media reports say, unplanned urbanization and construction of buildings flouting earthquake and fire safety guidelines are going on unabated in Sylhet, Chittagong and Dhaka – the three hot zones vulnerable to earthquakes.
The 2009 study found that a strong earthquake stemming from any of the three faults will cause massive destruction to buildings, bridges and supply channels of utility services in the three cities.
Chittagong is vulnerable due to Plate Boundary fault 1, 2 & 3 in the Bay while Dhaka, with the Madhupur blind fault, is vulnerable, even in a mid-level tremor, because of its high population density and high-rise concrete structures.
According to the study, some 142,000 of 180,000 buildings in Chittagong and 78,000 out of 326,000 buildings in Dhaka are extremely vulnerable to earthquakes. Moreover, some 130,000 people could be killed right away if an earthquake of 7.5 magnitude, originating from the Madhupur blind fault, strikes the capital.