Etna: the Northern Slope
The Northern slope of Mount Etna is characterised by the impressive presence of the North-East Crater that dominates the summit area that little more than a century.
This crater has been for decades the site of continuous and intense Strombolian activity with constant growing of the ashes, slag and lapilli cone that is today the highest part of the volcano.
It was formed in 1911 at an altitude of 3.100 metres, the North-East crater has grown slowly, reaching almost an altitude of 3.300 metres above the level of the sea in 1971 and 3.345 metres at the end of 1978.
The North-East Crater has gone through the years 1957-1964 and 1966-1971 two long periods of slow but constant effusive activity.
After a long break, the North-East crater has waken up in July 1996 with an stunning eruption during which, for the first time in the history of the Etna eruptions, it happened a unique event: the lava spilled from the western flank of the North-East crater has poured into the Central crater and then back into the bowels of the earth.
The northern slope has been affected by innumerable historical eruptions; the most important one and the one lasting the longest period that has been recorded on the volcano until today, is the one in 1614-24, originated under the Monti Deserti (today covered by the lava of the North-East crater) at an altitude of 2.600 metres on the Northern slope of the volcano and it was already defined by the Recupero in the last century as "a monster among the Etna eruptions".
That lava flow created a composite lava field, with spectacular examples of lava of Hawaiian type (rope lava), "budello" and "drappeggio", that extended on the Northern slope in an area of around 24 km, with a length of more than 7 km, and after having destroyed big extensions of beech and oak forests stopped just below the Mount Collabasso at an altitude of 900 m.
Within the lava field of the eruption of 1614-24 were covered many volcanic grottoes, the most famous one is the so called "Grotta del Gel", called in this way due to the perennial presence of ice in the deepest part of the cave; it is of great interest also the "Grotta dei Lamponi" that it is found in the whereabouts of the so called "Passo dei Dammusi". Among the most recent eruptions, instead, the most dangerous and destructive one was that of 17-23 March 1981, that threatened directly the inhabited area of Randazzo and that in only 14 hours interrupted the two provincial roads, the Circumetnea Railway and reached the right bank of the Alcantara river. It stopped at the edge of the river just above Piano Provenzano at the so called Rift of North-East, one of the most fractured area of the volcano, there are dozens of adventitious cones and eruptives fractures placed in a broad band of around a Kilometre and 3-4 km long, along which they are aligned Mount Pizzillo, Mount Nero, Mount Frumento, Mount Cacciatore, Mount Timpa Rossa, Mount Corbara, and the Craters Umberto and Margherita to form a striking moonscape.
The northern slope presents interesting ground covers, among which the pine forest of Ragabo (or of Linguaglossa), it is the most extended one in the Etna area, formed almost entirely of large specimens of larch pine, (the only spontaneous conifer of our Volcano), many of them exceeding 20 metres height, or still the beech forest of Monte Timpa Rossa and of Monti Spagnoli, that are the most southern beech forest in Europe, to witness and remember periods of cooler climate than the current one.
Just as glacial relicts are the birches (betula) of Etna that on the North-East slope (and to a lesser extent at the North-West) form the only birches of Sicily.
Above the limits of the forests (around 2.000 m) there are the "astragaleti" with their radical formations that stabilise the volcanic ashes and sands forming the grasslands at an altitude of 2.600 metres.
In the forests is not easy to see the animals, either because their fear of men (somewhat motivated) renders improbable an encounter, or because the tangle of branches, leaves and the bush undergrowth provokes their sound rather than the possibility to see them.
With a little bit of attention it should not be difficult to distinguish the rapid beat on the trunks of the great spotted woodpecker, the melodious song of the blackbird, the cheerful and monotonous song of the tit, and in summer, the unmistakable cuckoo.
The other inhabitants of the woods, shy and elusive (and especially at night!), rabbits, hares, foxes, dormice, porcupines, hedgehogs, etc. would permit us to see only their tracks.
Etna: the Southern Slope
The southern slope is characterised by the presence of different dozens of adventitious craters that can be observed when, once exceeded the town of Nicolosi, we start going up towards the top part of the volcano.
The summit part of Mount Etna facing the South has changed a lot during the XX century; today at the Grande Voragine or Central Crater are flanked two active craters: the South-West or Bocca Nuova that has been formed in 1968 by a cavity of diameter 8 m, increasing to 100 m of diameter in 1970; and the South-East formed the 18 of May of 1971, at the South-oriental flank of the Central Crater by a little collapse at an altitude of 3.050 m. The young crater pit, named South-East due to its geographic position in relation to the Central Crater, showed a modes activity until 1984, when it registered a noticeable increase of explosiveness creating a typical cone of slag.
The crater from 1971 until 1999 has been the seat of different phenomena of explosive and eruptive nature, often, with spectacular fountains of lava, Strombolian activity and subterminal eruptions.
The explosive episodes of 1989-1991 are unforgettable, also those of the Autumn of 1998, the subterminal eruption of 1999 and the 66 explosions of 2000 that have contributed to increase the size of the cone of the crater South-East on height and length several tens of metres.
The Southern slope is also characterised of the presence of the so called southern Rift, a weak area of the volcano some kilometres wide and along which there have opened several eruptive fractures.
So, within this range it is possible to observe the fractures of 1792, that one of 1892 that has given origin to the buttonhole of the Monti Silvestri, the fractures of 1886 and 1910, those of 1983, 1984, 1985, and the most recent eruptive fracture of the eruption of July-August 2001 from which they have come out lava flows that slowly have taken the direction of Nicolosi.
Right near Nicolosi stand out the mounts Rossi, formed during the terrible eruption of 1669, which lava flows reached the city of Catania destroying it partially and venturing to the sea for more than a kilometre.
It is not surprising that also the vegetation has suffered the effects of a big number of old eruptions, recent and very recent ones that have affected this slope.
Therefore, here, more than in other slopes the vegetation landscape is continuously broken, interrupted, transformed into a mosaic of microenvironments, each at a different stage of plant colonisation that slowly will transform the stony place into a forest.
And, so, black tongues of nude bare lava, and slightly coloured by a thin layer of lichen, go across forests, ginestra and grasslands, until it reaches an altitude of 2.500 metres approximately, and enters in the so called "Volcanic dessert", the vegetation cover disappears and there remain some exemplars of truly and extraordinary pioneer plants of considerable altitude.
And, it is on this composed landscape that there are many animals that find in these different environments the ideal conditions for their lives; and especially so if the wood is home to rabbits, foxes and small passerines, in grasslands of high altitude will find refuge hares and partridges, while hostile rocky places will be preferred by wheatear.
Etna: The East Slope
The oriental slope of Mount Etna is characterised by the impressive depression of the Valley of Bove. In the South is limited by the Serra del Salifizio, that with the Montagnola (crater of 1763), passes to the apparently soft uphill of the Schiena dell’Asino, that leads to the Summit Craters, whilst up North there is the Serra of the Concazze and mark the boundaries.
From Mount Cagliato (1.154m) rises the southern ridge that together with Mount Fontane (1.278 m.) Mount Cirasa, Mount Scorsone, Mount Rinatu, Serra of the Concazze reaches the 2.847 m of the Pizzi Deneri, whilst on the background it is possible to admire smoking summit craters.
We can observe and recognise the system of dikes called "serre" or "castles" (big Serra Giannicola, little Serra Giannicola, Serra Perciata) and the old volcanic centres of Rocca Musarra and Rocca Capre, two spikes of rock, that like stacks emerge among the darks lava flows of 1811 and 1986-87, and the adventitious craters of Mount Simone (formed during the eruption of 1811) and the Mount Rittmann (formed in 1987).
Large 6 km and long 7 km, this wide valley with a flat bottom has a U-shaped profile that, in the past, has assumed a glacial origin.
Until recent times it was instead considered a caldera testimony of a violent upheaval that has determined the end of the volcanic composition of the current Etna.
This hypothesis has lasted a long time, may be because it would appeal the catastrophic imagery that is part of everyone.
More realistically, the Valley of the Bove is instead the result of the construction activity of the different volcanic activities going on in the area, and the erosive phenomena, here particularly active that for dozens of million years have shaped the East slope, rendering it as it is today.
The Valley of the Bove happens to be almost "bounded" by the rift of N-E and by the S-E, important weak points, due to the presence of fault systems still today seismically active (as it is shown by the current activity), for million years renew and rejuvenate constantly the landscape.
Thus, the exogenous agents could act easily, digging, eroding and shaping up the landscape in order to create a unique environment, arid and desolate, but primordial and fascinating.
If the volcanologists managed to read on the steep sub-vertical walls almost as they would do on an illustrated book, the old history, ancient and recent of the volcano, and rebuilt the past events interpreting the tangle of dikes (old Magma routes), neck and lava flows that intersect on the walls, for everyone "common mortals", it has to do with the reassuring reservoir in which most of the biggest lava flows coming from the summit craters overhang the occidental walls, or with the fractures that opened on its flanks.
The list of eruptions, whose tracks, twisted and standing barely articulated in shades of gray and black of a thousand streams that are intertwined, juxtaposed and superimposed at the bottom of the valley, is almost infinite.