By Phil Stewart
Rome - An underwater volcano with a base larger than Washington DC has been discovered just off the shores of Sicily, a scientist with Italy's National Institute of Geophysics and Vulcanology said on Thursday.
The volcanic structure, which incorporates peaks previously thought to be separate volcanoes, was named Empedocles after the Greek philosopher who named the four classic elements of earth, air, fire and water.
Legend has it that the philosopher died by throwing himself into Mount Etna, the nearby Sicilian volcano.
Giovanni Lanzafame, who works at the institute and led the research, said Empedocles was at least 400 metres high - taller than the Eiffel Tower.
He said the base of the structure was 30km long and 25km wide, spanning an area larger than the US capital and making it Italy's largest underwater volcano.
But Lanzafame said Sicilians did not need to worry about the sleeping Empedocles. "At this point, there's no imminent danger of an eruption," he told Reuters.
Lanzafame and another official said the volcano had numerous fumaroles, openings in the Earth's crust that emit steam and gases, like the ones at Yellowstone National Park in the United States. But they described it as largely inactive.
The identification of Empedocles came during research into the submerged volcanic island of Ferdinandea just off Sicily's southern coast. Often held to be the tip of a small volcano, Lanzafame said it was just a part of Empedocles.
Volcanic activity has raised the island out of the sea several times in recorded history, with underwater eruptions first described during the first Punic War of 264-241 BC.
Its emergence in 1831 caused months of international wrangling, with several nations making territorial claims before it submerged again. It is now about seven metres below the surface of the water.
Cesare Corselli, president of the National Inter-University Consortium for Marine Science, which helped with the research, said previously the volcanic centres had been seen as separate.
"People used to think that there were small centres of emission, distant from each other," he said.
"The hypothesis made by Mr Lanzafame is that this is a singular volcano that, like alongside Etna as an example, can have a central eruption or a series of lateral eruptions."
Lanzafame said he had been working on the theory about the Empedocles's existence for more than a year before being able to confirm it with new survey equipment.