As live footage of monster waves surging through north-eastern Japan was being beamed in TV screens across the world, the question that crossed the minds of Bangladeshi viewers was: can this happen to Bangladesh? After all, Bangladesh is a low-lying country, which as repeatedly borne the brunt of tidal waves, especially during cyclones.
Experts say the country does face the threat of tsunami, as there are at least four active sources of earthquake in the Bay of Bengal, each of which can generate tremblors with magnitudes of over 7 on the Richter scale.
One of the deadliest earthquakes, to strike this region, took place in the Bay of Bengal in the morning of December 26, 2004, with the epicentre off the western coast of northern Sumatra in Indonesia. The tsunami triggered by the quake had waves 15 metres high, and even reached the shores of Somalia, about 4,500 km west of the epicentre.
Bangladesh, despite being a low-lying country, had escaped the wrath of the tsunami at that time, but experts don't see any reason for the country to rest easy. The country still has no early-warning systems in place, to detect tsunamis or to monitor the sea-level or recording storm surges.
Experts said it would seem unacceptable to allow the nation's coastal defence mechanism to degrade to the extent, whereby they cease to provide adequate protection to life and property. The government's stand, therefore, may not appear to be rational, as millions of coastal population cannot be left at the vagaries of nature.
Handing over of the coastal embankments system to a beneficiary, is likely to be as difficult as for inland schemes, in the immediate days. As in other countries, the coastal defence system must be expected to remain largely the responsibility of the government, the experts suggested.
Experts said that one of the sources generated an earthquake measuring 7.8 on the Richter scale, in 1762, which generated waves in rivers and other water bodies, and it is said that around 100 people had died as boats were overturned by the strong currents in the Buriganga.
All the four sources in the Bay – F1, F2, F3 and F4 – can lead to earthquakes of over 7 on the Richter scale, which, in turn, can unleash tsunamis that will affect country. Experts predict that sea levels can rise by 4-5 metres at Nijhum Dwip, while they rise by 2-3 metres at the Sundarbans, Cox’s Bazar and the estuary of the Meghna.
Seven major earthquakes have struck Bangladesh during the last 150 years and only two had the epicentre within the country. The Srimangal earthquake July 8, 1918, was recorded at 7.6 on the Richter scale, and its epicentre was in Balisera valley near Srimangal. Although there was damage, the intensity rapidly decreased due to the shallow focal depth and only minor effects were felt in Dhaka, he said.
The Bengal earthquake of July 14, 1885, caused considerable damage in the Sirajganj-Bogra region and perhaps more severe destruction in Jamalpur-Sherpur-Mymensingh region. The magnitude of the earthquake was more than 7 on Richter scale and the epicentre was at Manikganj.
During the 1762 earthquake in Chittagong-Arakan coast, the magnitude was 7.6, but the exact epicentre remained unclear.
The great Indian earthquake of June 12, 1897, that had a magnitude of 8.7, with the epicentre in the central part of the Shillong plateau is recalled as one of the world’s worst.
News Source: The Independent