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Summit of Etna

Snow-covered summit cone of Etna, April 1990

Etna Decade Volcano, Sicily, Italy

volcano number: 0101-06= (according to Volcanoes of the World, 1994 edition)

summit elevation: 3350 m

location: 37.734°N, 15.004°E

Contents

NE Crater

One of Etna's major centers of activity, Northeast Crater began erupting in 1911 and since then has built a prominent cone with an associated lava apron around it. Since November 1995, Northeast Crater has been the site of repeated violent explosive eruptions. This view was taken on 7 October 1995, in the early stage of the present eruptive period. A very dense, sulfur dioxide-rich plume rose from the crater which is visible here from the E rim of the "Voragine" crater (which more or less is to be considered the old "main" crater of Etna).

Introduction

Etna is Europe's largest and most active (in the sense of "productive") volcano, with frequent periods of intermittent to persistent activity in the summit area and major eruptions from eruptive centers on its flanks every 2-5 years. The main feature of Etnean activity is voluminous lava emission, but strong explosive activity occurs occasionally, mostly from its presently four summit craters.
Since Etna is featured well on the WWW server of the Istituto Internazionale di Vulcanologia, Catania (Italy), the volcano is presented here in a more general way. An emphasis is put on the eruptive history of the volcano which will culminate in a list of all recorded Etna eruptions and brief summaries of more recent eruptions, another one on the volcanic hazards aspect which at Etna is increasingly significant.
As in the case of all volcanoes presented on these pages, the information given is based on the work of many people. All credits go to them while my contribution is (hopefully) to present an accurate view of Etna, one of Earth's most notable volcanoes.

May 1996

Etna seen from the lower E flank on 11 May 1996, following intense activity from NE Crater. The photo was taken from the highway Catania-Mseeina, near Zafferana. The "shoulders" of Valle del Bove are visible to the left and right of the steaming summit cone complex..

Etna is particular for a number of reasons. First, it has the longest record of historical eruptions (see Volcanoes of the World, 1994 edition) among all volcanoes on this planet, its first historically documented eruption occurring at about 1500 BC. The total number of eruptions is 209 eruptions (18 among them questionable) through late 1993 (Volcanoes of the World). To these, there has now to be added the ongoing eruptive period from Etna's Northeast Crater (named NE Crater hereafter) initiated in the summer of 1995.
Etna lies in an area that is still not well understood from a geological standpoint. While some scientists relate the Etnean volcanism to subduction of the Ionian oceanic seafloor beneath the Calabrian Arc (with volcanism on the Aeolian Islands as one consequence), others postulate a hot spot beneath Etna, thus explaining its high lava production and fluid mafic magmas. Still another hypothesis sees Etna in a complex rifting environment. Whatever of this is true, it is evident that Etna lies in a very complex geodynamic environment hardly comparable to any other region on Earth. There is some evidence that Etna is but the most recent manifestation of volcanism fed from a very long-lived mantle source, having caused numerous earlier phases of mafic volcanism in the Monti Iblei, SE Sicily, through the early Pleistocene.
Another peculiarity of Etna lies in the fact that it is, like all dangerous Italian volcanoes, densely populated. The Catania area is Sicily's largest urban agglomerate (with more than 1 million people), consisting not only of the city itself but of numerous smaller towns and villages that at altitudes of up to 900 m (Nicolosi). Lava flows from historical eruptions of Etna have frequently covered areas now occupied by villages and tourist facilities. While Vesuvio is presently inactive, and may remain so for centuries, Etna shows no sign of entering into a long repose period soon.

Volcanic hazards at Etna

1992 lava flows

Night view of lava flows running down Val Calanna, and towards inhabited areas. The threatened town of Zafferana lies out of the photo towards the right. 20 March 1992.

Although generally considered a rather "harmless" volcano because devastatingly explosive eruptions are very rare (with the strongest explosive activity being confined to the summit craters), Etna is a potentially very hazardous volcano. The hazard is primarily from lava flows which do not present a significant threat to human lives but a serious one to property. The amount of damage to be expected is strongly related to several variables among which the mass eruption rate and the location of eruptive vents are the chief ones. The lower the location of the eruptive vents, the more dangerous will be the eruption. Since only few eruptions have occurred from low-lying vents in this century, the hazard has been, and is still, seriously underestimated.

(To be continued)

Other sources of Etna information on the WWW

Page set up in October 1995, last modified on 7 July 1996