The number of deaths in 1997 was 2,900 in 1997 and even fewer died in 1996 - 419. But the Director of NEIC told BBC Online that the average annual death toll over this century is 10,000.

Dr Waverly Person said: "The average over last 18 years has come down to about 8,000. That reduction is probably due to countries making buildings safer."

Worst case scenario

The worst case scenario is a large earthquake with a shallow epicentre (5 to 25km deep) in a populated area. The tremors which hit Columbia on Monday fulfilled all these criteria, leading to heavy loss of life.

"We have estimated the Columbian earthquake's epicentre at 17km down and at magnitude 6.2 - a strong one," said Dr Person.

The Afghan earthquake on 30 May 1998 killed over 4,000 people

Only a small number of earthquakes are responsible for the majority of deaths. In 1998 just two earthquakes of magnitudes of 6.9 and 6.1 in Afghanistan and Tajikistan were the site of over 70% of that year's deaths.

The largest earthquake of 1998 was magnitude 8.3, enormously violent, but injured no-one as it occurred under the ocean between Australia and Antarctica.

Declining death tolls

Seismologists point out that it is buildings that kill people, not earthquakes by themselves. Advances in making houses less likely to collapse during shaking have caused death tolls to decline, despite the rise in world population.

"More and more people are being concentrated in urban areas which makes the effects of any earthquake much worse and some countries find it hard to afford the cost of making houses safe," said Dr Person. "But I still expect the average number of annual deaths will continue to fall as people become more aware of what big earthquakes can do."

Dr Person said that the impression that earthquakes were becoming more common is wrong - the last two decades has seen a below average number of earthquakes of magnitude 7.0 to 7.9.