Stromboli

Stromboli is a small island in the Tyrrhenian Sea, containing one of the four active volcanos in Italy. It is one of the Aeolian Islands, a volcanic archipelago north of Sicily. This name is a corruption of the ancient Greek name Στρογγυλη (Strongulæ) which was given to it because of its round swelling form.

Stromboli also refers to a food originating on this island made of pizza dough, mozzarella cheese, and other ingredients. It is also known as a calzone.

Stromboli is remarkable because of the length of time for which it has been in almost continuous eruption. For at least the last 2,000 years, the same pattern of eruption has been maintained, in which explosions occur at the summit craters at intervals of minutes to hours. This type of very mild explosive eruption is known as Strombolian activity when observed at other volcanoes. Stromboli's activity is almost exclusively explosive, but lava flows do occasionally occur - an effusive eruption in 2002 was its first in 17 years.

The continuous mild explosive eruptions are also occasionally punctuated by much larger eruptions, which may generate earthquakes, pyroclastic flows and tsunamis. Large eruptions occur at intervals of years to decades, and the most recent large eruption began in 2002, causing the closure of the island to non-residents for several months. The largest eruption of the last hundred years occurred in 1930, and resulted in the deaths of several people and the destruction of a number of houses by flying volcanic bombs.

Stromboli stands approximately 900m high above sea level, but in total rises over 2,000m from the ocean floor. There are three active craters at the peak. A significant geological feature of the volcano is the sciara del fuoco ("Scar of fire"), a broad channel on the north western side of the cone. Eruptions from the summit craters typically result in lava rolling down this channel.

Historic account of the crater

Several enterprising travellers have ascended to the crater of Stromboli. It was examined with great care in 1828 by M. Hoffmann, a Prussian geologist, who, while being held fast by his companions, leaned over the crag immediately above the crater, and looked right down into one of its active mouths. His description of what he saw follows.

Three active mouths were seen at the bottom of the crater. The principal one, in the middle, was about two hundred feet in diameter; it shows nothing remarkable, only fuming slightly; and numerous yellow incrustations of sulphur coat the walls of its chimney. Close by this mouth is another, somewhat nearer the precipice, only twenty feet wide, in which I could observe the play of the column of liquid lava, which at intervals poised itself at a level. This lava did not look like a burning mass vomiting flames, but as glossy as molten metal -- like iron issuing from the smelting furnace, or silver at the bottom of a crucible.

This melted mass rose and fell -- evidently urged by the powerful tension of elastic vapours pressing it upwards from beneath; and it was easy to perceive the balance of effect between the weight of the molten masses and the pressure of the steam which resisted them. The surface rose and fell rhythmically: there was heard a peculiar sound, like the crackling of air from bellows entering the door of a furnace. A bubble of white vapour issued at each crack, raising the lava, which fell down again immediately after its escape. These bubbles of vapour dragged to the surface of the lava red-hot cinders, which danced as if tossed by invisible hands in rhythmic sport above the brink of the opening.

This play, so regular and attractive, was interrupted, every quarter of an hour or so, by more tumultuous movements. The mass of whirling vapour then rested motionless for a moment -- even making a jerking motion of return, as if inhaled by the crater, from the bottom of which the lava rose more strongly as if to encounter it. Then the ground trembles, and the walls of the crater starting bend. It was quite an earthquake. The mouth of the crater uttered a loud rolling bellow, which was followed by an immense bubble of vapour, bursting at the surface of the lava with a loud thundering report. The whole surface of the lava, reduced to glowing splinters, was then tossed into the air.

The heat struck our faces forcibly; while a flaming sheaf rose right into the air, and fell back in a shower of fire all around. Some bombs ascended to a height of about 1200 feet, and in passing over our heads described parabolas of fire. Immediately after such an eruption, the lava withdrew to the bottom of the chimney, which then yawned black and gaping. But erelong there was seen re-ascending the shining mirror of the surface of lava, which then recommenced the rhythmic play of its ordinary less violent bubblings.

External links

• Satellite Image of Stromboli Island (http://www.terraserver.com/imagery/image_gx.asp?cpx=15.2187496894358&cpy=38.8017325382372&res=15&provider_id=320&t=pan)de:Stromboli

it:Stromboli (isola) mt:Stromboli nl:Stromboli pl:Stromboli