The water level will rise 2-3 metres at the Sundarbans, Cox's Bazar and the estuary of the Meghna.

Kamal said seven major earthquakes 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 seven on the Richter scale and the epicentre was at Manikganj, he added.

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 was recalled as one of the world's worst.

He said any minor earthquake might be due to the activity in the local small fault zones, thus increasing the chances of a major jolt happening. Besides, Ansary felt a strong earthquake could occur in the plate boundaries as the 100-year alarm bells have passed.

Bangladesh is close to the meeting point of the Indian, Eurasian and Burma (Myanmar) plates. The movement of Indian and Eurasian plates has been locked at the foot of the Himalayas for many years, storing strain energy, he said.

When the lock is released, it will let out the strain energy causing major earthquakes that will affect Bangladesh, northeastern India and Myanmar, Ansary explained.

Three strong earthquakes were recorded from the Indian-Eurasian plate, which jolted Bangladesh within 150 years, said Ansary.

Due to the Indian and Eurasian and Myanmar plates, the Bihar-Nepal earthquake took place in 1934 and it was felt as far away as Dinajpur and Rangpur, he said.

The Assam earthquake Aug 15, 1950 had a magnitude of 8.6 on the Richter scale. The tremor was felt throughout Bangladesh but miraculously no damage was reported anywhere.

But the Mandalay earthquake that struck in 1858 with a magnitude of 7.9 affected Chittagong division, he added.