Beneath the sparkling waters of the Mediterranean--far from the eyes of visitors marveling at the majesty, or trembling at the destructive potential, of Mount Vesuvius and Mount Etna--Italian scientists are studying two less visible volcanoes that, while presenting no immediate danger, have generated considerable interest. The Marsili seamount--submerged in a few thousand meters of water north of Sicily--has the theoretical potential to wreak havoc some day by generating seismic waves known as tsunamis that could conceivably wash away large portions of the scenic Amalfi coast and other areas. South of Sicily, Graham Island, also known as Ferdinandea, last emerged from the sea 169 years ago before vanishing again. Theoretically, at least, it could be reborn as an island.
Less theoretical waves have been created by journalists who have stirred public anxiety with dire warnings of imminent eruptions and underwater landslides that could set off tsunamis. Not likely, say the scientists, who downplay the risk. "Geologically speaking, it's a possibility," acknowledges Boris Behncke, a German researcher at the University of Catania's department of geological sciences in Sicily. "But geology has a very long time scale ... We really should not be too worried."
Still, the geologically active Mediterranean seabed--where the earth's Eurasian and African tectonic plates come together--maintains a powerful grip on the imagination. One of the more fascinating scenarios surrounding seamounts--dozens of which dot the floor of the Mediterranean--involves the possible re-emergence of Graham Island, which made its first recorded appearance in 10 B.C. and last rose from the sea between Sicily and Tunisia in July of 1831. The volcano bubbled and spat for several months, then submerged again--peacefully ending an ownership dispute involving Britain, France and what was then known as the Kingdom of the Two Sicilies. Its peak is now roughly 8 m below the water's surface.
Europe's biggest seamount, Marsili, discovered in the early 1960s, rises about 3,000 m from the sea floor and has a summit that is some 500 m below the surface. Measuring roughly 70 km by 30 km, Marsili is the main seamount among three that rise more than a kilometer in the Marsili Basin of the Tyrrhenian Sea, as the portion of the Mediterranean north of Sicily and west of the Italian mainland is known. Numerous cones dot the volcano, many of them worn flat by erosion.
According to Michael Marani of the Italian National Research Council's Marine Geology Institute in Bologna, excitement over Marsili began last December when data from the Marsili Basin showed evidence of landslides on the mountain's flanks. Some of the Italian press, misinterpreting the findings, buzzed with claims that the seamount was about to erupt. If Marsili blew, the stories said, the resulting landslides could set off a series of long, high waves that could devastate a vast area of Italy from the Campania region around Naples to Sicily. In fact, says Roberto Carniel of the University of Udine's department of georesources and territories, Marsili has shown signs of collapse from several thousand years ago. Sooner or later, he says, it could happen again, unleashing landslides that could produce a major tsunami. "But it's a hypothesis of 2,000 or 5,000 or 10,000 years down the road," says Carniel. "There are no signs of activity now, and certainly no signs of collapse."
Volcanologists are keeping watch just the same. Marsili and all volcanoes deeper than 300 m below the sea's surface present no explosive threat because water pressure prevents them from blowing their tops, explains Marani. "The real danger is when a flank or a large volume of the volcano collapses. If that happens under water and the volume is great enough, it could produce a tidal wave ... Marsili is an active volcano and should be monitored. If it were on land, we would be doing that." (On land, Italy's--and Europe's--greatest danger remains the 1,281-m Mount Vesuvius, near Naples, because about 1.5 million people live around the mountain and on its lower slopes. Vesuvius is quiet now, but Mount Etna--Europe's most active and, at 3,350 m, its tallest volcano--began shooting out ash and rock on Feb. 1.)
When Graham Island, as Britain calls the fickle seamount that last emerged from the water about 50 km south of the Sicilian seaport of Sciacca in 1831, its appearance was as much a political event as a geological one. Observers at the time wondered if a chain of mountains would spring up, linking Sicily to Tunisia and thus upsetting the geopolitics of the region. On July 13, 1831, fountains of lava gushed along a fissure, exploding on contact with the water and spitting out billowing clouds of black ash. Three nations rushed to claim the island. The English fleet landed, named it Graham--for Sir James Graham, the first lord of the admiralty--and planted a flag. But the government of the Kingdom of the Two Sicilies dispatched the corvette Etna to claim the new land and dub it Ferdinandea in honor of King Ferdinand II. Last on the scene was Constant Prevost, a co-founder of the French Geological Society, who compared the eruption to a bottle of champagne being uncorked. Bearing the flag of France, he named the island Julia, because it was born in July. Diplomatic wrangling broke out, but was soon resolved by the island itself. Said to have stood at 70 m above sea level and measuring 700 m in diameter, it crumbled in on itself and all but disappeared by the end of the year. By January 1832 it had sunk completely.
Pierluigi Maria Rossi, a professor of volcanology at the University of Bologna, says the sunken island is just, in a sense, letting off steam. "It's a very young volcano," he notes, "and with all young volcanoes there's going to be gas released." Enzo Boschi, director of the National Institute of Geophysics and Volcanology in Rome, agrees. "There are bubbles and waves," he reports, "but that doesn't mean the island is about to be reborn. It just means the zone is active." If Ferdinandea were to come back, adds Boschi, its appearance would be preceded by strong tremors, felt also on shore, and the emission of gas would be visible from quite a distance. "This would last for some 20 to 30 days before the island emerged--and not be a risk except to some fish and fishermen," he concludes.
Should Ferdinandea reappear, Federico Eichberg, an international relations expert based in Rome, believes it would do so within Italian territorial waters--and in all probability would be formally claimed by Italy. Eichberg does not expect that any international dispute would arise, noting: "If it's just a little island, we're not going to have a big fight over it." Likening premature talk of a reborn Julia to a "virtual tour of virtual islands," a French Foreign Ministry spokesman postulated nonetheless that the island would not have the same strategic importance today that it had in 1831. A diplomatic dispute would be highly improbable, the official suggested, and the island would likely belong to Italy. But a spokeswoman for Britain's Foreign and Commonwealth Office kept all options open. The British government "would look at this if and when any island were to emerge," she said, adding: "We don't want to make waves now."
In making waves over Marsili and Graham Island, Italian journalists may have missed a bigger story. Because of its precarious location at the intersection of two geological plates, says Boschi, the Mediterranean itself could well be destined to disappear hundreds of millions of years from now. Will it? Only time--geological time, that is--will tell.
With reporting by Greg Burke/Rome and Sarah Davis/Paris