Monitoring Mt Etna: an eruptive internship!

This guest post was written by Josh Brown, a NERC IAPETUS Doctoral Training Candidate, who spent two months interning at the Etna Volcano Observatory in Sicily. During his time at the observatory he took part in a unique public engagement project; writing a field guide for tourists about the geological features of the island.

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In the final year of my PhD research, I had the incredible opportunity to spend two months working at Etna Volcano Observatory (INGV Osservatorio Etneo) in Sicily. The Observatory are responsible for monitoring the activity of Mt Etna volcano and providing warnings to the public and aviation sector about the impacts of volcanic eruptions. I’d like to thank Rosanna Corsaro, Salvo Giammanco and all the staff of Osservatorio Etneo for hosting me and teaching me so much about volcano monitoring, and the NERC IAPETUS DTP for funding this experience.

Just a day before I arrived in Sicily, a new eruption of lava began from Etna’s south-east crater, fed by vents at around 2800 m elevation. On only the third day of my internship, I had the opportunity to join a team of Observatory staff who were tasked with observing the lava flow and reporting on the activity of the volcano to the authorities.

During the day, the orange colour of the lava was hard to see (Picture 1) so we used a thermal camera (Picture 2) to determine how far the molten part of the lava flow had travelled into the valley below the crater. We also observed many small explosions (Picture 3), throwing out ash and blocks of molten lava, from the top of the south-east crater. Once the sun set, the glowing orange colour of the lava became visible, treating us to a spectacular view (Picture 4)! The eruption continued for around a month, with the lava flow eventually extending down to around 2000 m elevation. The lava flow posed no threat to civilization and instead became a popular tourist attraction whilst it was active.

A more unusual field day was the visit to the “Salinelle” or “mud volcanoes” near the town of Paterno on the south-west flank of Etna. The “mud volcanoes” are a series of vents that erupt muddy fluids, which are composed of a mixture of water and gases derived from underlying sedimentary rocks and carbon dioxide which has escaped from magmas deep below Etna. Picture 5 shows a bubbling mud volcano vent with Etna in the background. The mud volcanoes are a surprisingly useful indicator of upcoming volcanic eruptions! In the weeks to months before volcanic activity begins, the temperature of the muddy fluids increases and sometimes large eruptions of mud occur. These events are likely triggered by large volumes of gas which escape from the rising magmas that go on to erupt at Etna, explaining why the mud eruptions occur shortly before volcanic eruptions.

My work at the Observatory also involved the creation of a geological field guide for tourists, explaining the geological features of the Cyclopean Islands on the eastern coast of Sicily. These islands represent rocks formed by the cooling of magma beneath the seafloor during the early stages of evolution of Mt Etna and have since been lifted above the sea surface by tectonic movements. A particular feature of the islands is the exceptional columnar jointing (Picture 5), formed by contraction of the magma as it cooled. The geological field guide should be published soon on the Osservatorio Etneo website (link below) – keep a look out for it if you wish to learn more about the geology of the Cyclopean Islands.

The Observatory aims to collect samples of lava from each of Etna’s eruptions, which provides a record of the activity of the volcano over time. Many of these lava samples have been made into thin sections (30 micron-thick slices of rock), which can be studied under a microscope. A photo of a thin section from a lava erupted in 2008 is shown in Picture 6. By studying thin sections, the Observatory staff and researchers can identify different types of crystals in the lava. Many researchers measure the chemistry of crystals in thin sections, which can be used to obtain information such as the depth that the erupted lava came from. This information is useful to the Observatory as it provides an indication of where magma is stored beneath the volcano, which can help them interpret volcano monitoring data and better predict future eruptions.