One of the highlights of the EUROVOLC summer school was undoubtedly the day-long fieldtrip on Mt Etna, visiting the North-East rift zone with our expert guide Stefano Branca, who has spent many years mapping the eruptive deposits of the volcano. An early 8.30 am start was required to make it to the small town of Piano Provenzana, over 2000 m above sea level, where the trail began. On arrival, the impacts of Etna’s eruptions were immediately noticeable, with the road leading to the town built on top of the wide lava flow of the 2002-03 eruptions. It turns out that this event was particularly bad for the population of Piano Provenzana, which was mostly destroyed and buried by flowing lava (see below).
As we began climbing up towards the rift, we noticed some small ash plumes rising from the summit. However, we were reliably informed by our guides that these were caused by collapse of sections of the north-east crater rather than new magma reaching the surface. After clambering across the rubbly surface of the 2002 flows, we reached some deep holes and a line of cone shaped structures. Stefano informed us that the holes were in fact eruptive vents from 1914, where dykes propagated along the NE rift and fed fissure eruptions along its length. These built up the cones by continuously erupting small, bubble rich fragments of magma (scoria) and larger lava bombs.
We then moved on towards the much larger Monte Nero scoria cone, formed during the famous eruptions of 1669, where lava reached the major nearby city of Catania, causing serious damage. On the flanks of the scoria cone, extremely large, metre sized lava bombs were found by the path, indicating just how powerful this eruption was. Unfortunately at this point the weather took a turn for the worse, forcing us to retreat to a bar in Piano Provenzana.
After a long lunch, the weather improved and we headed to a multi-parametric monitoring station, to see the equipment we had been learning about all week. The stations are built into the ground, contain both seismometers and GPS units, and are powered by solar panels. These instruments continuously transmit data to the INGV observatory in Catania to allow real-time monitoring of the volcano.
Our final stop of the day was the Pernicana fault, which extends from the NE flank of Mt Etna to the coast. Earthquakes and large, up to metre scale movements are common on the fault, which is helping to facilitate the slow sliding of Etna’s east flank towards the sea. In the field, the fault is marked simply by a ditch next to a steep rock face, which exposes lavas from prehistoric eruptions of Etna uplifted by several slip events.
Soon I’ll be covering the final days of the summer school, as well as adventures from my second visit to the Caribbean!