Submarine volcano off Italy may be a tsunami threat

Map showing the location of submarine volcano Marsili, near the Italian coast. Image from INGV.

The subject of submarine volcanism near Italy has come up before here on Eruptions but now it has made the jump into the worldwide media after some claims made by Enzo Boschi, president of the National Institute of Geophysics and Volcanology (INGV).

The long and short of what I can tell from the articles is that Marsili, a submarine volcano in the Tyrrhenian Sea, could be a threat to create a significant tsunami that would hit Italy (amongst other Mediterranean countries). The volcano lies only 150 km / 90 miles to the southwest of Naples and is under ~450 meters / 1500 feet below sea level. The fear is that an eruption of Marsili would cause part of the edifice to collapse, producing what could amount (in a worst-case situation) to an undersea version of the Mt. Saint Helens 1980 eruption. It could also just suffer from edifice collapse, producing a tsunami similiar to what happened at Unzen in Japan in 1792.

Now I am no expert on the state of research on some of these submarine Italian volcanoes, but some of the articles seem to suggest that the volcano is “ready to erupt”. My favorite line might be from an AFP article that states “The Marsili volcano, which is bursting with magma, has “fragile walls” that could collapse”. I’ve never heard of a volcano as being “bursting with magma,” but I fear something could have been lost in translation along the way. The evidence presented in the article does suggest that Marsili could be more of a threat to Italy than previously thought, but I fear that the following quote from Boschi is being liberally interpreted:

“Our latest research shows that the volcano is not structurally solid, its walls are fragile, the magma chamber is of sizeable dimensions. All that tells us that the volcano is active and could begin erupting at any time.”

(my emphasis).

Now, I read that final phrase as meaning that it is an active volcano, thus future activity is likely – it could be soon, it could be hundreds or thousands of years from now, but the volcano is likely not extinct. However, my guess is that many of the news outlets read that phrase as “it is going to erupt very soon!“

If you want to see some excellent dissection of the Marsili reports, head on over to the Volcanism Blog. You can also see some additional comments on this news from Boris Behncke. For now, I think we can all agree that Marsili should be on our radar as a volcanic threat to Italy, but some of the headlines out here (e.g., “Volcano tsunami could engulf Italian coast ‘at any time’“), as usual, are a little over-the-top.

{Thanks to Aldo Pombino for some of the links in this post.}