UNC Scientists Have a BLAST in Italy Over Break!

             A UNC-CH seismic expedition this summer led by Jonathan M. Lees to Stromboli Volcano, located at the northern end of the Aeolian island arc off the southern coast of Italy, proved to be as successful as it was adventurous. 

            Stromboli Volcano is one of the few volcanoes in the world known to be in permanent explosive volcanic activity.  This activity, known as “Strombolian,” is generally mild and has shown a rhythmicity of seven explosions per hour during historical times.  We, however, are fortunate enough to attest first hand to the large variety of expressions of which Stomboli is capable.  While standing less than 30 meters away, we witnessed explosions in excess of 30 per hour, but in 24 hours the explosions had slowed to less than 10 per hour and were steadily gaining strength.  The volcano that had seemed so contained, although anything but calm, suddenly flexed its muscles and had us all on our toes!  It is certainly a humbling experience to stand so close to such a great force of nature.

            Despite the explosions, a bit a bad weather, unexpected encounters with tourists, and a challenging hike to look forward to each day, we were able to install an array of three seismic stations, each equipped with a broadband seismometer and an infrasonic microphone, around the flank of the volcano.  Within a week we had more than enough data for a successful experiment thanks to the high level of activity at Stromboli.

            Data analysis has already begun on the data with plans to produce a statistical analysis of the Stromboli’s explosions by vent, as well as over time. We are excited to have recorded very long period signals (>2 s), which are possibly indicative of magma movement, at Stromboli.  These signals are very new to volcanology due to the previous unavailability of broadband seismometers.  With our current data and future research, we hope to contribute to the cutting edge exploration of the source of these signals.

            As a bonus (though in retrospect perhaps the most outstanding segment of our expedition), we were invited by our Italian colleague to participate in a seismic survey of Mount Etna volcano, a majestic stratovolcano standing over 3,000 m tall, located on the mainland of Sicily.  You may have heard this volcano mentioned recently in the news due to its latest series of violent eruptive episodes, which began on July 17, just six weeks after our departure. 

 The first major eruption since the 1991-1993 flank eruption has proved to be a very spectacular, complex, and danger case of summit and flank activity occurring simultaneously.  Detonations were reported to be audible as far as Catania, even during the hours of intense traffic, with atmospheric shock waves that rattle doors and windows. Bulldozers had to be used to create earth barriers to contain or divert this flow, which in its upper course damaged a ski lift. More far-reaching effects resulted from the continuous rain of fine ash produced by the explosive activity. During the early morning and forenoon of July 22, a heavy shower of ash fell over Catania, forcing the closure of the international airport of Fontanarossa for three hours. Since the beginning of August, this eruption and resultant lava flow has slowed, stopping just shy of the village of Nicolosi, but no one has relaxed just yet. 

During our stay at Mount Etna, we installed the first broadband seismometers in history near the summit, as well as an infrasonic microphone, with great success.  In light of Etna’s recent exposure, we are anxious quantify the data we collected and look forward to sharing some preliminary conclusions of both experiments in the near future.