The Greatest Show On Earth: Etna, 5 January 2012 Etna is known to be one of the most active volcanoes on Earth. Many also believe it to be a rather harmless, good-mannered volcano, which most of the time is true, although (quite rarely, like once every 200-plus years) it does indeed bury entire villages under lava flows, and the risk of lava invading populated areas is quite elevated. However, there is no elevated risk for those areas when the volcano erupts from one or more of its four summit craters – there’s just a high probability to feel emotionally overwhelmed by the sheer beauty of the summit eruptions. Last year, during the night of 12-13 January 2011, Etna returned on the scene after one-and-a-half years of repose, producing what technically is called an “eruptive episode”, a short-lived event (normally lasting only a few hours), but also the word “paroxysm” is often used for this sort of event. “Paroxysm” implies something rather violent, and Etna’s paroxysms are violent indeed, but most of all, they are breathtakingly spectacular. The year 2011 eventually saw 18 paroxysmal eruptive episodes from Etna, some of which were of exceptional beauty, most were quite well documented both in photographs and video, which then made the tour of the world via the Internet. My small YouTube video collection contains a few scenes from several of those paroxysms. The latest occurred on 15 November 2011 and once more was of fierce beauty and sheer violence – an act of brutal creation, which left a mountain 200 m tall, the result of 18 short-lived episodes whose activity collectively would make up less than 2 days, a mountain that had not been there ten months earlier. Then Etna took a deserved break that continued through the Christmas festivities and into 2012, that year already notorious long before it began. As long as there were no significant eruptions anywhere on this planet in the new year, the world was made shiver with make-up “news” about a “super-volcano” in the heart of Germany (and thus of all of Europe) threatening to erupt – some Italian secondary news site even spoke of “Red Alert” in Germany, which is an immense blast of pure phantasy, given that the alleged “super-volcano” is not behaving anomalously in any way. As though she had enough of the chitter-chatter, Etna finally decided to make the REAL news again, and so she did as magnificently, splendidly, and scenically as was positively imaginable. She delivered The Greatest Show On Earth, like she has done about 200 times since the mid-1990s, but with a particular taste for details. She waited until one system of bad weather had moved away from the area and acted just before the next moved in. She chose that short interval between night and day – already spectacular by itself when weather conditions are good – when there are the most gorgeous colors and lights. And then she pulled the full register of volcanic versatility, doing Strombolian explosions, lava flows, lava fountains, columns of ash and gas, opening of eruptive fissures, and then even pyroclastic flows and small lahars – volcanic mudflows. Go figure that one of the most outstanding publications treating Etna as a volcano, the grand “Mount Etna, Anatomy of a Volcano” by british scientists Chester, Duncan, Guest, and Kilburn published in 1985 (and still very much valid today) did not mention pyroclastic flows among volcanic hazards at Etna. It was known that some very large explosive eruptions long ago (like, 15,000 years ago) had produced some massive pyroclastic flows, but
since then, it was believed, its tempers had eased. Strombolian activity and quiet emission of lava flows was considered the most typical activity at Etna, hardly a severe threat to human lives, although lava flows can indeed be very destructive. In recent years we have started to understand that pyroclastic flows are far more common at Etna than imagined – in at least twelve or thirteen cases they are known to have occurred since 1986, and I have personally had the chance to see them four times, on 25 October 1999, 16 November 2006, 10 April 2011, and 20 August 2011. At the height of the 5 January 2012 paroxysm, I had the opportunity to witness this particular, potentially extremely dangerous, destructive and deadly phenomenon again – luckily from a very safe distance, but equipped with the best camera I’ve had so far. The scenes of the pyroclastic flows descending from a heavy curtain of falling volcanic rock onto the steep flank of the New Southeast Crater cone and impacting still pristine snow fields at the base of the cone make up much of this video. I hope that the geologists among you who watch this will appreciate the significance of what you see here – it’s geology and geological knowledge in the making.
2/2 Powered by TCPDF (www.tcpdf.org)