Virtual Volcano Vacation #44 WINNERS! – Etna

etna erupts

Original image found at NY Daily News

It would seem that Jesper was right. I could not hide on Mount Etna for long..but I had to find out for myself anyway. Besides, this is one of my favourite volcanoes and I had only briefly dropped in once before while stumbling around looking for Stromboli in the dark.

And what’s NOT to like about this volcano! It is the tallest mountain in Italy south of the Alps, is the tallest active volcano on the European continent, standing at “around” 3,329 meters. (It tends to change height frequently with summit eruptions) and is one of the most active volcanoes on Earth.

Etna is a work-in-progress 500,000 years in the making. The earliest basaltic activity at Etna formed a large shield volcano. Then beginning about 35,000 years ago her lava became more viscous, thus the growth of the younger stratovolcano atop the old shield volcano. During the next 20,000 years, Etna experienced several highly explosive eruptions which produced large pyroclastic flows and ignimbrite deposits. Ash from one of those eruptions has been found as far as 800 km away just south of Rome. Around 8,000 years ago, possibly due to a culmination of caldera collapses, a large portion of the volcano’s eastern slope collapsed, creating the Valle de Bove (“Valley of the ox”). The collapse caused a tsunami that left its telltale mark upon other locations in the Mediterranean.

valle de bove

The Valle de Bove – Original image found at Il Cherubino B&B

It is situated above the fault between the African plate and the Ionian microplate, both of which are subducting under the European plate, but the lighter Ionian microplate has “rolled back” creating an opening of sorts that lets Etna get her magma supply almost directly from beneath the African plate. This explains why Etha is so active, and why her lavas are more like those erupted from deep-sea trenches than the re-melting of existing crust.

etna ionian microplate

Diagram of the tectonics beneath Mount Etna – Original image at Nature.com’s International Weekly Journal of Science

Etna’s eruptive history is a lengthy read. Her summit eruptions are rarely troublesome, but flank eruptions can become deadly as there are many villages established well up her flanks.  Highlights include a VEI 5 plinian summit eruption in 122 BCE which deposited damaging tephra upon the rooftops of structures in Catania to the southeast. The damage was significant enough that the Roman government exempted Catania from taxation for ten years so they coud rebuild. In 1669 an effusive eruption destroyed at least ten villages on Etna’s south flank before reaching the walls of Catania. There, most of the lava was diverted but eventually the wall was breached. Strangely the advancing lava stopped just short of the Benedictine monastery. Other Etnean eruptions have been described by the likes of Homer and Virgil, and one particularly damaging modern eruption beginning in October of 2002 was recorded by Lucasfilms and immortalized as “planet Mustafar” in Star Wars III Revenge Of The Sith…..for what that is worth.

At present, Etna has four almost continually active summit vents as well as 350 assorted monogenetic vents and fissures around her flanks. Her eruptions are the most ubiquitous and most recorded of any volcano on Earth, and in spite of being considered one of the most dangerous, the people of Sicily love her and have nicknamed her Montebello (or alternates Mongibello or the Sicilian language Mungibeddu), “The Beautiful Mountain”, as well as Muntagna “the Mountain” …or also simply “the lady” or Vulcanessa.

etna snow

“The Lady” in her “white dress” – Original image at Italia.it

Congratulations to Jesper for finding me, and to Leslie for being first to identify the pyroclastic cone Monti Centenari in the Valle de Bove. Next week (barring additional illnesses) begins a new adventure at a new volcano.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s