Salina volcanic island, Aeolian Islands, Italy

volcano number: not catalogued in Volcanoes of the World

summit elevation: 964.64 m

location: 38.635°N, 014.877°E

Salina is the green jewel in the Aeolian Archipelago. It has the tallest mountain of the islands (which many people wrongly believe to be Stromboli on the island of the same name - actually Stromboli is 38 m lower than Monte Fossa delle Felci, Salina's highest peak, at nearly 965 m), and politically, Salina represents a peculiar case compared to its sister islands. While the other six main islands (Lipari, Vulcano, Stromboli, Filicudi, Alicudi, and Panarea) are under the administration of the town of Lipari, Salina has three individual municipalities: S. Marina Salina, Malfa, and Rinella. Each of these consists of two villages. Some 2500 people live on the island, which has so far managed to escape from the mass tourism that affects most of the neighbor islands in the summer. To some people Salina represents a little "Switzerland" in the Aeolian Islands, which is certainly also due to its unusually green and mountainous aspect. The island hosts one of the first natural parks that were created in Sicily, which initially was limited to Monte Fossa delle Felci but now extends also over its twin peak, Monte dei Porri.
The two large volcanic cones that make up the bulk of Salina and differ by only 100 m in height (Monte dei Porri rises to 860 m) stood at the origin of Salina's ancient Greek name, Didyme (twins). Seen from certain directions (especially from south and north), the shapes of the two huge cones are in fact nearly identical. However, the geology of Salina is much more complex, and the number of more or less well-preserved volcanoes that constitute the island is five. Their activity overlapped during certain periods and was characterized by violent explosive activity and milder, cone-building Strombolian and effusive activity. The youngest of the five volcanoes, Pollara, lies in the northwestern corner of the island and its scenic landscape has featured strongly in the cult film "Il Postino (The Postman)" (1994). Pollara never developed into an elegant cone like the older volcanoes on Salina but much of its activity was extremely explosive and carved a large crater into the northwestern flank of Monte dei Porri. The latest eruptive activity at this center occurred about 11,000-13,000 years ago and blanketed much of the surroundings with pumiceous pyroclastic flow deposits. Submarine fumaroles lie immediately offshore from the Pollara explosion crater, and it is not certain whether Salina will erupt again in the future.
Visitors to Salina are enchanted by its verdure and magnificent and changing landscapes, which can be explored on a well-maintained road network and numerous hiking trails. In the summer, while the other islands in the Archipelago are overwhelmed by a huge surge of countless tourists, Salina maintains a relatively calm atmosphere, and fortunately it has been largely spared from uncontrolled construction of hotels and apartment complexes, which, for example, has destroyed some of the original beauty of Vulcano and Lipari. Hikers will enjoy the forests of Monte Fossa delle Felci and the breathtaking panoramic views that can be obtained from its summit and also from neighboring Monte dei Porri. But maybe the most beautiful place to visit is Pollara, the explosion crater of the youngest volcano on the island. The houses of a small village with less than 60 inhabitants lie scattered on the gently sloping crater floor; a miniature harbor lies below a vertical cliff (exposing a spectacular section through lake sediments that filled the Pollara crater after its eruption), and not far away from there at Punta Perciato (the pierced point) a huge natural arch rises some 50 m above the sea surface, eroded into a pre-explosion lava flow erupted from the Pollara volcano.

Salina at a glance
Area: 26.5 km2 Location: 4 km NW of Lipari Highest elevation: 962 m Age of volcanism: ~0.5 Ma to 13 ka Rivi and Capo volcanics ca. 0.43 Ma Fossa delle Felci (1st cycle) 127-100 ka Porri volcanics: 100-66.5 ka Fossa delle Felci (2nd cycle) 24->13ka Pollara volcanics 30-<13 ka	Notable morphologic features: Monte Fossa delle Felci (965 m) Monte dei Porri (860 m) Monte Rivi (854 m) Pizzo del Corvo (529 m) Crater of Pollara (diameter about 1 km, depth 0-500 m) Residents: about 2500

Simpified geological map of Salina, from Barca & Ventura (1993). 1=reworked pyroclastics, undifferentiated; 2=pyroclastics of the 3rd Pollara cycle; 2a=pyroclastics of the 2nd Pollara cycle; 2b=lavas of the 1st Pollara cycle; 3=lavas and pyroclastics of the 3rd Monte dei Porri cycle; 3a=pyroclastics of the 2nd Monte dei Porri cycle; 3b=pyroclastics of the 1st Monte dei Porri cycle; 4=pyroclastics of the 5th and 6th Fossa delle Felci cycle; 4a=pyroclastics of the 4th Fossa delle Felci cycle; 4b=pyroclastics of the 3rd Fossa delle Felci cycle; 4c1=Lavas of the 2nd Fossa delle Felci cycle; 4c=dacitic lava dome of Punta delle tre Pietre (2nd Fossa delle Felci cycle); 4d=lavas and pyroclastics of the 1st Fossa delle Felci cycle; 5=lavas of Corvo volcano 6a=lavas and pyroclastics of the 2nd Rivi-Capo cycle; 6b=lavas and pyroclastics of the 1st Rivi-Capo cycle; 7=dikes and sills of the shallow feeding systems of Corvo and Rivi-Capo

Geological evolution

The geological history of Salina is characterized by the successive growth and erosion of five major volcanic edifices: Rivi-Capo, Corvo, Fossa delle Felci, Porri and Pollara. Recent authors divide the evolution of the island into three main stages. The Rivi-Capo and Corvo volcanoes began to grow about 430-500 ka (430,000-500,000 years) ago and are strongly eroded, but must have had large edifices. The Rivi-Capo complex apparently formed on a long ENE-trending fissure, while Corvo was probably a central volcano. Erosion has exposed the central portion of Corvo, which shows countless dikes and larger intrusions. Late in the first stage, about 127 ka ago, volcanic activity began to build up the Fossa delle Felci cone. Andesitic-basaltic lavas and pyroclastics were erupted during this period, although Calanchi et al. (1996) also note the formation of a dacitic lava dome in the southern portion of the volcano.
The activity then underwent a long hiatus, during which marine conglomerates were deposited on the lower slopes of the volcano. Following this hiatus, the Fossa delle Felci volcano resumed its activity, marking the beginning of stage 2 in the evolution of Salina. Calanchi et al. (1996) describe the activity as cyclic, starting with strong phreatomagmatic explosions that produced pyroclastic surges and flows, and then developing into Strombolian or fire fountaining activity accompanied by lava emission. The composition of these products ranges from andesitic basalt to andesite. Spectacular sections through these deposits are ubiquitous on the eastern flanks of Monte Fossa delle Felci, such as in cuts along the road that connects S. Marina Salina with the villages of Lingua to the south and Capo Faro to the north. About 100 ka ago, when Fossa delle Felci was still in activity, a new eruptive center (Porri) became active to the WNW. It initially produced lava flows but then powerful phreatomagmatic explosions generated pyroclastic surges and pyroclastic flows that covered all of the then-existing island, surmounting even the topographic barrier of Fossa delle Felci, which at that time was probably about as high as today. Following this exceptionally violent activity, Monte dei Porri grew during about 30,000 years of magmatic activity, characterized by Strombolian activity, lava fountains, and emission of lava flows, which are uniformly andesitic basalts. The symmetrical stratovolcano that resulted from this activity ceased erupting about 67 ka ago.
The third stage of the geological evolution of Salina is marked by the growth of the Pollara volcano in the northwest part of the island, which started about 30 ka ago, and terminated with two violently explosive events about 13 ka ago. The initial activity of Pollara consisted of the emission of dacitic lava flows, which are exposed at Punta di Perciato and Scoglio Faraglione. About 24 ka ago, Monte Fossa delle Felci became active again and produced a small volume of scoriae and ash, which overlie older lavas on the crater rim. Following its initial effusive activity, Pollara apparently remained quiet for a long period, during which magma differentiated in a shallow reservoir, with its most evolved portion being dacitic to rhyolitic. An intrusion of fresh, and hotter, basaltic magma into the reservoir triggered the major explosive eruptions at the end of the Pollara (Calanchi et al., 1993). A palaeosol sandwiched between the pyroclastic deposits has been dated at about 13 ka. The explosions generated voluminous pyroclastic flows and surges, which left thick deposits in the northwestern part of Salina. A 1 km-diameter crater was carved deeply into the northwestern flank of Monte dei Porri by this explosive activity. Subsequently the explosion crater was filled by a lake, which was gradually filled by remobilized pyroclastics, before the western half of the crater collapsed into the sea, probably along a tectonic structure. The lacustrine deposits are now exposed in the spectacular cliff that forms the coast near Pollara, while sections further north expose the thick sequence of pyroclastic flow deposits of the final Pollara eruptions.

Left: the characteristic silhouette of Salina with its symmetrical twin volcanoes of Monte dei Porri (left) and Monte Fossa delle Felci (right), seen from south in September 1995 Center: panoramic view from the summti of Monte dei Porri, September 1996. Monte Fossa delle Felci, the tallest mountain of the Aeolian Islands, is seen at right, while the lower peak at left is the older and strongly eroded volcano Rivi. The narrow belt devoid of vegetation is a fire barrier protecting the forest of the Monte Fossa delle Felci Natural Park (now extended into the Natural Reserve of the "Montagne delle Felci e dei Porri") Right: view from the summit of Monte dei Porri into the large explosion crater of Pollara, September 1996. Half of this crater has collapsed into the sea, the small rocky islet (Scoglio Faraglione) being the only trace of the collapsed portion of the volcano. The remaining crater floor is occupied by the scenic village of Pollara

Spectacular outcrops of pyroclastic deposits making up the Rivi-Capo complex, along the road from S. Marina Salina to Capo Faro, in the northeast portion of Salina island. Light-colored deposits were created by phreatomagmatic activity (pyroclastic flows and surges), brown deposits are soils indicating hiatuses in the eruptive activity. The reddish brown and black deposits were laid down during Strombolian activity and fire-fountaining. Note absence of lava flows in these outcrops. Photos taken in September 1996

Pollara, the youngest volcano of Salina. Left photograph shows the 1 km-wide amphitheater created by the massive explosive eruptions at the end of the Pollara activity, about 13,000 years ago. The tall mountain at left is Monte dei Porri, whose northwestern flank was destroyed when the Pollara crater was torn out of its side. - Photograph at center is another view of the Pollara crater from Punta di Perciato, looking southeast. The near-vertical cliff in the foreground exposes numerous horizontal layers that are sediments (reworked pyroclastics of the Pollara explosive eruptions) deposited within the lake-filled Pollara crater before its near half collapsed into the sea. The cone of Monte dei Porri rises in the background, and some of its internal stratification is exposed where its flank was dissected by the Pollara crater. - Right phototgraph shows the spectacular natural arch of Punta di Perciato. It is constituted by a thick dacitic lava flow emitted during the first activity of the Pollara volcano. Yellowish rocks in the right foreground are pyroclastic flow and surge deposits emplaced during the final explosive activity of Pollara. Photographs were taken in October 1995

Deposits of the final explosive eruptions at Pollara. Left photograph shows lithic-rich deposits emplaced during vent-clearing explosions at the beginning of the activity. Large blocks were derived from dacitic lavas emitted during the earlier activity of Pollara. Center photograph shows massive pyroclastic flow deposits with peculiar erosive "chimneys", which may mark the site of post-emplacement fumarolic pipes where the deposits were cemented and thus are more resistent to erosion. In the right photograph grayish-white pyroclastic flow deposits are seen in outcrop along the road between Pollara and Malfa, with thicknesses of several tens of meters. The peculiar "swiss cheese" pattern is a result of erosion. Photos were taken in September and October 1995

References

Barca D and Ventura G (1993) Evoluzione vulcano-tettonica dell'isola di Salina (Arcipelago delle Eolie). Memorie della Società Geologica Italiana 47: 401-415

Calanchi N, De Rosa R, Mazzuoli R, Rossi P, Santacroce R and Ventura G (1993) Silicic magma entering a basaltic magma chamber: eruptive dynamics and magma mixing - an example from Salina (Aeolian Islands, Southern Tyrrhenian Sea). Bulletin of Volcanology 55: 504-522

Keller J (1980) The island of Salina. Rendiconti della Società Italiana die Mineralogia e Petrologia 36: 489-524

Lanzafame G, Ricci Lucchi F and Rossi PL (1987) Evidence of surges overtopping a large topographic barrier: Salina island, Aeolian Archipelago, Italy. Journal of Volcanology and Geothermal Research 32: 355-361

Mazzuoli R, Tortorici L and Ventura G (1995) Oblique rifting in Salina, Lipari and Vulcano islands (Aeolian islands, southern Italy). Terra Nova 7: 444-452

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Copyright © Boris Behncke, "Italy's Volcanoes: The Cradle of Volcanology"