This was revealed by a leading geologist on Thursday when explaining why the South Asian country remained safe from the tsunami led by the massive earthquake on sea floor near Indonesianisland of Sumatra, 1,019 km away from Chittagong, the second largest city of Bangladesh.

Mir Fazlul Karim, Director of Geological Survey of Bangladesh (GSB), with the help of United States Geological Survey (USGS), is heading a team of GSB experts to study the impact of the earthquake that triggered a massive tsunami or sea surge ripping through a wide area on the Indian Ocean from Sumatra to Somalia.

The team is entrusted with the job of thoroughly studying the impact of the Dec. 26's earthquake-triggered tsunami, and suggest ways and means of developing a Bangladesh model of survival against it with early warning and precautions.

The GSB director said the shallow water on the continental shelf of Bangladesh slowed down the onrushing sea surges before they could ravage the country's coastline.

As a gift of nature, the continental shelf is forming on the Gangetic delta with billions of tons of sediments carried by the Ganges and the Brahmaputra from the Himalaya for years.

The depth of water on the Bangladesh coast is 10 to 20 meters, Karim said, which helped to absorb the impact of the onrushing seasurges whipped up by the tsunami effect.

"Although we have survived with God's mercy and natural barrier,we are yet to be out of the woods as danger is always lurking. We need to develop a system of early warning against more powerful sea surges", Karim was quoted as saying, adding there is no immediate chance of a tsunami hitting the country again, but Bangladesh should be prepared for a moderate quake on the onshore.

Although the continental shelf is shielding Bangladesh from a severe tsunami effect, in the southernmost area of the country along the Bay of Bengal from Cox's Bazar to St Martin's Island, the southern tip of Bangladeshi territory, the seabed there is a little deeper than the shallow coastline on the Meghna estuary to the Sundarbans, said Karim, thus he suggested people from this area should move with caution.

He said there had been a moderate quake of 5.5 on Richter scaleover the country's eastern border with India on Dec. 26 at night, which went virtually unnoticed but a result of the aftershock of the morning tremor on the day, indicating that the Indian and Myanmar tectonic plates on the earth's crust are on a collision course always, moved further by the Australian plate following theSumatran earthquake.

There was another tremor measuring 5.3 on the Richter scale at Myanmar near Chittagong on Thursday morning, added karim.

Such tremblers are indicating the movement of the Indian plate on which Bangladesh is sitting above the earth's crust, he said.

The Indian plate is moving two to three mm every year toward northeast, bringing it into collision course with the Eurasian andBurmese plates, increasing the chances of tremors onshore. "So farthe tremors occurred in Bangladesh had been moderate, which suggests that we may not have a very severe quake soon," added Karim.

Karim further suggested that Bangladesh Meteorological Department, GSB, Space Research and Remote Sensing Organization, as well as Bangladesh Navy and the Air Force who use satellite data, sit together to develop a tsunami warning system with available resources.