Experts predict massive quake
2004-10-04 07:54
Paris - Europe is due for another massive earthquake like the one which struck Portugal in 1775 killing an estimated 60 000 people, a French scientist warns.
New evidence shows that the activity in the earth's crust which triggered the Great Lisbon quake is continuing.
But it may be a few hundred years before another disaster happens.
Research indicates that powerful earthquakes are likely to occur in the region at 1 000 to 2 000 year intervals.
The 1755 earthquake hit Lisbon on November 1 as worshippers in Portugal and southwestern Spain gathered for mass on All Saints Day.
Churches packed with people were toppled by the quake, which scientists estimate had a force of magnitude 8.7.
The earthquake also triggered a tsunami - or giant wave - five to 10 metres high.
Recent evidence suggests that the quake was triggered by one of the great plates that make up the earth's crust sliding under another beneath the Straits of Gibraltar.
A long term seismic risk
Expert Dr Marc-Andre Gutscher, from the European Institute of the Sea in Plouzane, France, said this "subduction" process still appeared to be continuing today.
Writing in the journal Science, he said: "An active subduction zone off southern Iberia poses a long term seismic risk and is a likely candidate for having produced the Great Lisbon earthquake of 1775."
Active mud volcanoes in the Gulf of Cadiz off the south-western coast of Spain provided one clue suggesting that the threat remained.
Other evidence had emerged from marine seismic and heat-flow data.
Deposits on the deep ocean plains off south-west Iberia suggested that great earthquakes had struck the area regularly every 1 000 to 2 000 years.
Earthquake experts are planning major expeditions to the region as the 250th anniversary of the disaster approaches.
Five oceanographic cruises are planned between 2004 and 2005, and three new proposals have been submitted for drilling beneath the sea floor.
"Together, the new studies may help to unlock the secrets of this region's past and its likely future," said Dr Gutscher. - Sapa-dpa
- SAPA