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Ferdinandea / Graham Island

The Ferdinandea volcano is in the Mediterranean Sea, around 30 kilometres off the coast of the Italian island of Sicily. It is part of the underwater volcanic complex of Empedocles. The peak of Ferdinandea is usually a few meters below the surface of the sea. Several times over the past 2000 years it has erupted and added new material to itself, emerging from the sea. . Graham Island (also known as Ferdinandeo Bank) is part of the Campi Flegrei del Mar di Sicilia (Phlegraean Fields of the Sicily Sea), a group of submarine volcanoes constructed within a depression about 1000 m deep SW of Sicily.

This island was the focus of a territorial dispute between Sicily, France and England, until January 1832 when the island had been eroded away. It was situated in latitude 37 11' North, longitude 12 44' East. A few years before the eruption, a depth of more than 100 fathoms existed on the spot.

It showed signs of volcanic activity in 2000 and 2002, forecasting a possible appearance. According to news articles, Enzo Boschi, the head of INGV, stated that seismicity increased near Campi Flegrei Mar Sicilia a group of submarine volcanoes ~30 km S of Sicily, near Tunisia. Boschi stated, "The island could come back to the surface, but we'll have to wait and see... It could be a few weeks or months." The Stromboli On-Line website noted that similar statements have been made several times in the past couple of years. The increased seismicity does not necessarily signify that an eruption is imminent and the island will re-emerge above wave base. However, as of 2017 it remained 6 meters (20 ft) under sea level.

This short-lived island, which rose in the Mediterranean, received no less than seven names. The seven rival names are Nerita, Ferdinanda, Hotham, Graham, Corrao, Sciacca, Julia. As the isle was visible for only about three months, this is an instance of a wanton multiplication of synonyms which has scarcely ever been outdone even in the annals of zoology and botany. Ferdinandea, in honor of his Sicilian Majesty, Sciacca and Graham Island are those which have been most generally adopted.

Towards the end of June, 1831, Sir Pulteney Malcolm in passing over it experienced concussions like those of an earthquake, as if his ship had struck on a bank. On 28 June 1831 the volcanic island appeared between Sicily and North Africa. The submarine activity which produced the volcano called Graham's Island was made the subject of several good observations.

The eruption in July 1831 was one of the most violent, and contributed important facts to the study of the red sunsets and the blue sun. The mass of vapors thrown up by Ferdinandea was enormous, and comparable to that which was launched from Krakatoa ; it formed a column over the volcano at least fifteen miles high. But no ashes were carried away by the winds from Ferdinandea, because the seawater rushed into the crater after each eruption; and this explains the formation of such masses of vapor. But, although there were no ashes the phenomena of blue or green suns and red twilights were observed over a great part of Europe.

On July 10 and 11 the fiery column was magnificent. In the beginning of August there was an immense column of dust; on August 5 the dust was carried to a distance by the wind. In the beginning of July, some Neapolitan vessels reported a violent ebullition of the sea, and the emission of columns of smoke and vapor. About July 10, John Corrao, the captain of a Sicilian vessel, reported that, as he passed near the place, he saw a column of water like a water-spout 60 feet high, and 800 yards in circumference, rising from the sea, and soon afterwards a dense steam in its place, which ascended to the height of 1,800 feet. The same Corrao, on his return from Girgenti, on July 18, found a small island, elevated twelve feet above the sea, with a crater in its center filled with boiling water of a dingy red color, and ejecting volcanic matter; the surrounding sea being covered with dead fish and floating scoriae. The diameter of the crater was at that time estimated by Captain Swinburne at seventy or eighty yards, and it had an outlet on the side by which the boiling water escaped.

The eruptive phenomena were nearly similar to those observed off the Azores. Columns of steam, accompanied by discharges of scoriae and dust, were thrown up to the height of several hundred feet, a loud roaring noise, and the formation of a vast quantity of steam, accompanying their rise and their fall into the water; while forked lightning, followed by thunder, darted in all directions within the column, which was darkened by dust, and distorted by gusts and whirlwinds. Most of the stones ejected were less than a foot in diameter.

On the 3rd of August, when Captain Senhouse landed on the island, the crater was about 400 yards in diameter, and the island a mile and a quarter in circumference, and 160 or 180 feet high. It shortly after attained its greatest dimensions; the circumference being estimated at nearly 3 miles, and the height at 200 feet; after which it began to diminish by the action of the waves.

By August 4 it became, according to some accounts, above 200 feet high, and 3 miles in circumference ; after which it began to diminish in size by the action of the waves, and was only 2 miles round on August 25; and on September 3, when it was carefully examined by Captain Wodehouse, only 1/3 of a mile in circumference; its greatest height being then 107 feet. At this time the crater was about 780 feet in circumference. On September 29, when it was visited by Mons. C. Prevost, the circumference of the island was reduced to about 700 yards.

By October 1831 Ferdinandea had been washed away by the sea.

Towards the end of October the crater had disappeared, and the surface of the island was reduced nearly to the level of the sea; and about the end of 1833 the only vestige of it was a dangerous shoal, consisting of black stones and loose sand, with a solid rock in the centre, composed most probably of lava which had cooled within the crater. A second shoal occurs at the distance of about 180 yards to the southwest, where a minor eruption had been observed in August, 1831.

It was composed entirely of incoherent ejected matter, scoriae, pumice, and lapilli, forming regular strata, some of which are described as having been parallel to the steep inward slope of the crater, while the rest were inclined outwards, like those of Vesuvius. When the arrangement of the ejected materials has been determined by their falling continually on two steep slopes, that of the external cone and that of the crater, which is always a hollow inverted cone. Few of the pieces of stone thrown out from Graham Island exceeded a foot in diameter. Some fragments of dolomitic limestone were intermixed; but these were the only nonvolcanic substances.

It is obvious that the fragmentary matter ejected during submarine eruptions would not be arranged in a succession of conical layers, as in eruptions of subaerial volcanos; but being more widely diffused by the agitated waters, would form a solid tufaceous mass, derived from the boiling red mud, and enveloping scoriae, stones, fishes, and marine shells.



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