STROMBOLI
 
 

DESCRIPTION OF THE SITES SUGGESTED FOR A VOLCANOLOGICAL VISIT TO STROMBOLI

dépliant published by Dipartimento della Protezione Civile and Gruppo Nazionale per la Vulcanologia, Italy
Editorial Project: G. Pasquaré
Text and figures L. Benciolini , G. Pasquaré, F.A. Pasquaré
Drawings  M. Pasquaré
Graphic project P. Moneta e D. Noya
web-project: L. Giacomelli , R. Scandone




1 - Walking along the coast, beyond the pier, you will reach an outcrop of rock that cuts the beach. The outcrop shows the oldest lava flows of the island which, about 100.000 years ago, were moving down the slopes of Paleostromboli I, towards the sea, accompanied by flows of blocks and incandescent scoria.

2 - If you walk 10 m past the C.A.I. trail sign, at the end of the beach, you will notice, in front of you in the distance, several lava and scoria flows, emitted about 60.000 years ago by Paleostromboli II. Their regularly repeated succession indicates that, at that time, eruptions were continuous and took place with an abundant lava output.

3 - By following the trail along the beach and then turns right, you will reach an old quarry where you have a chance to observe the evidence of Vancori's initial eruption, which were extremely explosive. From the bottom to the top you can see lapilli-tuffs, a lava flow (orange), lapilli-tuffs again and finally pyroclastic flow products (yellow), genereted by clouds charged with steam and ashes, which, ejected from the vent, moved down at high speeds, close to the ground. Looking at the quarry, on your left along the trail, you can observe closely the lapilli tuffs, noting that tghey derived from a rain of lapilli and bombs, and that the falling bombs caused the down-sagging of the soft, underlying layered tuffs.

4 - You can reach this site by following the C.A.I. trail n. 14, which starts from the coastal road near the pier. Not far above the last house you can observe, along the trail, the pyroclastic flows of Vancori volcano. It is possible to see thinner layers rich in ash, and other layers rich in coarser rocky clasts, which were fragmented in the upper portion of the eruptive conduit. The presence of the fragments indicates we were not far away from the ancient crater.

5 - Following Stromboli's lowest road, after reaching the sign "Città del Sole" turn right towards the sea and you will reach the Grotta di Eolo. This cave is a lava tunnel, which formed after the surface of a lava flow cooled and solidified, developing a continous crust beneath which the still molten interior lava continued to flow toward the sea. As a result of this processes, a wide cave formed.

To the left of the Grotta di Eolo, beyond the cove, you can observe that a dense, solidified mass of lava has remained beneath the scoriaceous superficial crust. Therefore, it is possible to imagine that, in this area, the flow did not have enough energy to escape towards the sea and create another cave.

6 - Once you have reached the last bend but one in the trail that leads to the Osservatorio di Labronzo, leave the trail and climb up 50 m. In front of you you will see a long, deep and straight-lined valley, extending to the island's summit. This is a crevice which, 10.000 years ago, cut the flank of Neostromboli volcano. The fissure emitted fountains of incandescent lava spatter, whose remains are still visible in the vicinity of the cliff, as accumulations of reddish scoria.

7 - You can reach this site by following the trail that start from the Osservatorio Labronzo and leads to a green cabin. Climbing up a few meters past the cabin, you will reach the overlook that lies on the flows erupted by Neostromboli Volcano. Close to its margin you can see a dark, delta-shaped lava flow, which moved down along the Sciara in 1985.

8 - Following the trail that leads to the craters, after reaching the bend located at an altitude of 300 m, look in the direction of the Sciara and you will see the superimposition of Neostromboli Volcano on Vancori Volcano. Il is possible to notice an "angular unconformity" between the lavas of the two volcanoes, due to the different provenience of the two flows.

9 - A long stretch of the trail leading to the craters cuts grey ashes containg block and bombs, which cover the lavas of Neostromboli. The ash deposits resulted from the consolidation of a "nuée ardente" (glowing cloud) which flowed down from the summit crater during the exceptional explosive event that took place in 1930.
 

10 - If you keep moving upward, you will notice that the lavas of Neostromboli, which had remained indisturbed for thousands of years, were buried by a heavy rain of black scoria, during the 1930 eruption.

11 - At an hight of 650 m., along the same trail, not far above the previous site you can see the flows emitted during the years immediately following the formation of the Sciara del Fuoco. Currently, these flows are suspended above the bottom of the present Sciara. In the background you also see the hanging remain of Neostromboli. This fact demonstrates that the Sciara's collapses were numerous, and had the effect of leaving the previously erupted products isolated and suspended at gradually increasing distances from the bottom of the Sciara.

12 - Shortly before reaching the summit, in the vicinity of the walls of the first shelter, by observing the head of the Sciara del Fuoco you will notice the presence of white-yellow "islands" among the dark ashes erupted by the present cone. They are remains of Neostromboli, which have been chemically altered by corrosive action of the fumaroles, still visible in the upper portion of the cone. This demonstrates how, at Stromboli, every new volcano which had previously formed and was later deactivated.

13 - Walking upward along the trail, a few meters beyond the previous site you have the opportunity to observe the contact between 3 different volcanoes. The flank of the ancient Vancori Volcano was ripped apart on your right, about 13.000 years ago, by a giant collapse that originated a semicircular scar. The void generated by the collapse was filled, later on, with the products erupted by the more recent Neostromboli Volcano, and these were covered afterwards by ashes and debris that flow down abundantly from the present cone.

14 - It is possible to observe the present crater of Stromboli from the Pizzo Sopra la Fossa. The crater rim is continuously growing, due to the steady emission of ashes an scoria which, by falling on the crater rim, increase its height. You can distinctly see inside the crater the three cones ejecting steam and, at intervals, throwing into the air ashes and incandescent lava spatters.

15 - Following the trail that winds along the ridge, walk down 50 meters, and you can examine the internal components of the Pizzo Sopra la Fossa. You will notice that it used to be a cone (which was for a long time, Stromboli's summit cone), made up of blocks, ashes and lapilli, expelled during several, quite violent "Strombolian" eruptions. At present you see only one half of it, owing to the subsequent collapse of the Sciara del Fuoco.

From the same overlook you can notice, in front of you, the large amphitheatre left by the collapse of Vancori, which was examined at close range from site n. 13.

16 - Looking over the vast extent of ashes and lapilli of the Rina Grande, pause to observe the rocky rampart situated on your right. In this place, the black lavas quickly flowing down from the Pizzo Sopra la Fossa, had emough energy, thanks also to their particular fluidity, to move upward on the rampart's flank, which represents the remains of the escarpment left by Vancori's collapse.

17 - If you go twenty or so meters beyond site n. 16, you will have a chance to take a look at the rim of Vancori Volcano's collapse. The red lavas represent the recent products of Vancori, immediately preceding its collapse. The black materials are ashes and lapilli erupted by the recent and present activity, accumulated against the escarpment left by the collapse.

18 - Follow the trail that leads from site n. 16 to the summit of Vancori. Shortly before reaching the summit you will observe a large accumulation of blocks, scoria and bombs, ejected during a violent explosive eruption, which probably marked the beginning of Vancori's collapse.

19 - Walking along the trail that leads from the Rina Grande to Semaforo San Vincenza, before the last downhill stretch that goes through the canebrake, go to your left twenty or so meters and you will reach an accumulation of strongly welded scoria, associated with lavas. These are products which were emitted by an eruptive fissure that opened in the north-eastern flank of Neostromboli. The flows erupted by the fissure moved down and reached the sea, where they are still visible, East of Ficogrande.

In the background you can see Strombolicchio, an islet composed of lavic breccia. As you can see, numerous dykes cut the inslet. Strobolicchio represents the remaining portion of a volcano much older than Stromboli and nowadays completely dissected.

20 - Along the trail that leads from Ginostra to Timpone del Fuoco, near the last house it is possible to examine particular "ropy lavas", which have acquired their ropy shape due to the fluidity and flow velocity that characterize them. This flow came from the Timpone del Fuoco, the low cone-shaped relief in front of you, which was generated by an old parasitic vent of Neostromboli.

21 - Follow the trail that leads from the Timpone del Fuoco to the Punta dei Corvi. Looking over the Sciara del Fuoco you will see a sort of massive wall, which represents a dyke, which is the magmatic filling of a fracture that opened up in the past in the volcano's flank. Erosion then stripped away the weaker surrounding rocks, leaving the dyke isolated and higher than the relief around it.

22 - Reaching Ginostra's last houses, situated in the locality of "Lazzaro", you can take a look at the flank of the ancient Paleostromboli Volcano, carved by the Vallone Rina. The valley's incision enables you to observe how the volcano's body is segmented and interrupted by large fractures, which testify to the volcano's long and tormented history.

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