Etna Field Campaign

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Etna Field Campaign

Etna Geology

Photo courtesy of Laura Carmody

Mount Etna is Europe's highest and most active volcano rising to 3,310m and active for the last 0.5 million years. Activity started with the emission of tholeiitic basalt magmas in a submarine environment off the coast of Sicily before occurring on land 300ka in a region just southwest of the current summit. Activity initiated in the current eruptive centre around 170ka and is focused from 4 summit craters; NorthEast Crater, Voragine, Bocca Nuova and SouthEast Crater.

Classified as a stratovolcano, Mount Etna is comprised of alternating lava and pyroclastic units caused by phases of effusive and explosive eruptions. Strombolian activity and lava fountaining are common features of the summit craters whilst large lava emitting flank eruptions occur at intervals of years. Large explosive eruptions have also occurred at Etna with large ignimbrite depositis (35ka - 15ka) and a catastrophic collapse of the eastern flank generating the now Valle del Bove around 6000 years ago. The most recent summit collapse occurred 2000 years ago generating the Piano Caldera.

Recent publications have indicated that the volcano has become more active in the past 30 years with magma emission rates and euption frequencies up to 4 times greater than in previous centuries (Allard et al, 2006). This is thought to be the result of ascent of gas-rich (0.25 wt%) basaltic magmas which are subsequently stored at shallow depths (3-5km below sea level) (Spilliaert et al 2006).

Volcanic Degassing at Etna

Aiuppa et al, (2006) investigated the volcanic plume composition at Etna for a year long period between 2004 - 2005 using a portable gas analyser during periodic field surveys. The results of this show that the CO₂/ SO₂ ratio of the plumes orginating from the different summit craters at Etna vary between 1.9 to 10.8 with the Northeast crater and Voragine showing the greatest contrast. CO₂ emission rates during this period were estimated at 0.9 - 67.5 kilo tonnes per day (average of 9 kilo tonnes per day). During passive degassing in non-eruptive periods the amount of CO₂ is estimated at 2 kilo tonnes per day, whilst during the effusive activity in 2004 - 2005 a cumulative 3800 kilo tonnes of CO₂ was released over 6 months.

Figure from D'Alessandro 1997 illustrating the different sources of carbon that feed Mount Etnas plume, and also the approximate isotopic values of carbon of each of the sources.

Much work has already been carried out on Etna and carbon reservoirs contributing to Etnas CO2 gas emissions have been identified by D’Alessandro 1997 using isotope signatures. The wealth of the existing knowledge of Mount Etna makes it an ideal testing site for new technologies developed through VCO2 and so it can be regarded as a laboratory volcano. Trips in 2012 have already been planned to test the carbon isotope analyser being developed at the Rutherford-Appleton Laboratories.

VCO2 Trip to Etna (August 2010)

The first meeting of VCO2 took place in Nicolosi, on the slopes of Mount Etna from 31st August to 2nd September 2010 and had the following mains aims;

1. Discuss the equipment already in place measuring the plumes from Etna

2. Determine the next tehcnological steps to be taken

3. Outline the parameters within which equipment should work in terms of precision, threshold of measurements and environmental challenges.

4. Determine whether Mount Etna represents a good test site for new developments and any other volcanoes.

A brief report of the trip can be found here.

Details of the explosion on the 25th August 2010 can be found here.

References

Aiuppa, Federico, Giudice, Gurrieri, Liuzzo, Shinohara, Favara, Valenza. Rates of carbon dioxide plume degassing from Mount Etna volcano, J. Geophys. Res., 2006;111, B09207, doi:10.1029/2006JB004307.

D'Alessandro, De Gregorioa, Dongarràb, Gurrieria, Parellob, Parisib. Chemical and isotopic characterization of the gases of Mount Etna (Italy) Journal of Volcanology and Geothermal Research 1997;78:1-2:65-76

Allard, Behnckea, D'Amicoa, Neria, Gambino. Etna 1993–2005: Anatomy of an evolving eruptive cycle Earth-Science Reviews. 2006;78:1-2:85-114.

Spilliaert, Allard, Métrich, Sobolev. Melt inclusion record of the conditions of ascent, degassing, and extrusion of volatile-rich alkali basalt during the powerful 2002 flank eruption of Mount Etna (Italy), J. Geophys. Res., 2006;111, B04203, doi:10.1029/2005JB003934.

UCL Volcano CO2 Group