Monti Sartorius

The volcanic activity of Etna during the last 3 centuries shows the coexistence of two types of eruptions: central and flank. In central eruptions the magma is emitted, through explosive or effusive activity, from one or more of the four active summit craters, namely the Voragine, Bocca Nuova, North East Crater and South East Crater. During flank eruptions the magma is emitted along radial fractures from the central system on the side of the volcano, representing therefore a higher source of hazards for the populated area. The Strombolian activity, which generally takes place at the vents located in upper part of fissures, produces scoria cones due to the accumulation of proximal pyroclastic deposits, while lava flows are emitted at lower portions of fissures. To date, flank activity at Etna produced more than 300 monogenic scoria and spatter cones, localized mainly in the south, in the west and in the northeast areas of the volcano, at altitudes between 475 and 2990 meters above sea level (asl).

Monti Sartorius are a group of seven large monogenic scoria cinder-shaped cones, formed during the 1865 flank eruption and are so called in honor of the German volcanologist Wolfgang Sartorius. They are localized on the Northeast side of Mt Etna at about 1740m asl aligned along a system of fractures oriented ENE–WSW. The development of the craters chain along a straight direction is known as “bottoniera” (button line). The first signs of eruptions occurred on 28 January 1865, with ash emission at the base of Mt Frumento delle Concazze accompanied by seismic activity. Lava started to be erupted on 29 January 1865 at altitudes between 1724 and 1800 m, coupled with three lava fountains on the upper part of the fracture. On 30 January 1865 a 400m long fissure opened at east of Mt Frumento delle Concazze, feeding eight lava fountains. In the following days the activity was focused on the lower prolongation of the fractures, leading to the developing of the main cinder cones. They consist of alternating layers of welded and loose deposits, reflecting a variable intensity of the volcanic activity during the eruption. The markedly asymmetry of scoria cones is due to the persistent winds blowing at the time and to the pre-existing topography formed on underlying deposits.

The itinerary of Monti Sartorius is a loop, which runs for about 4 km starting from the road Via Mareneve, with a duration of about 2 hours and with maximum difference in altitude of about 150 m. Some elements of volcanological interest will be observed along the path, including the different types of lava bombs ejected during explosive activity, the features of the pyroclastic deposits, and the different morphologies of lava flows. The path also travels through some typical flora ecosystems of Mt Etna, such as birch woods and the shrubbery of Astracantha sicula, an endemic milkvetch/ghoat’s thorn plant locally known as spinu santu (holy thorns).

After lunch, we will make a quick visit to the Crateri Silvestri. These cones formed during the 1892 eruption, at an elavation around 1900m asl. The main lava flow form the resulting eruption reached a length of around 7km, brushing the Monti Rossi above the town of Nicolosy at 970m asl.

The Crateri Silvestri are among the most famous attractions on Mt Etna, and they are close to the highly touristic zone of the Rifugio Sapienza, a former mountain shelter now turned into a hotel/restaurant.

The fee for the trip is 65€ per person, and it covers transport, lunch and guides.

The programme for the day is the following: