Just imagine that dark hump at left was not there nine months ago.

Just imagine that dark hump at left was not there nine months ago., a photo by etnaboris on Flickr.

One of my favorite activities on Etna when it is not erupting is to document its various volcanic features - craters, cones, lava flows, but also the vegetation that develops on these features - because sooner or later these images will show places that are no longer there or look very different ... or entirely new features. Over the past 22 years, since my first visit to Etna in September 1989, the shape of the volcano has locally changed beyond recogition. The large cone in the center, the Old Southeast Crater with its steep sulfur-covered summit, was a low, unconspicuous heap of stones at the time of my first visit. Much of this cone grew during dozens of violent eruptive episodes ("paroxysms") between September 1999 and July 2001. In the spring of 2007 it erupted for the last time, then it passed on the job to a new vent on its lower east (left) flank.

That new vent was a collapse depression, something that is called "pit crater" in the volcanological terminology. This pit crater produced three large paroxysmal eruptive episodes in September and November 2007 and on 10 May 2008, just before the latest flank eruption of Etna. A new, small pit crater opened on 6 November 2009 on the lower east rim of the 2007 pit and gradually enlarged by collapse, and partly coalesced with the earlier pit. This constellation was the place where a first spectacular paroxysm with beautiful lava fountains and flows and a tall ash plume occurred during the moonlit night of 12-13 January 2011, and "the pit crater" became widely known.

Since then, there have been 10 more of these paroxysmal eruptive episodes, on 18 February, 10 April, 12 May, 9, 19, 25, and 30 July, and on 5, 12, and 20 August. Each of these events has thrown considerable quantities of volcanic rock onto the surroundings of the crater, which have gradually piled up into a huge, new volcanic cone, the newest volcanic construct that exists on this planet, and probably the construction is far from finished. This new cone now stands approximately 150 m above the elevation of the original pit crater; if it continues to grow at the same rate through another, say, 10 to 15 paroxysms, it might reach or even overtop the elevation of the old Southeast Crater. Chances are that Etna will continue to produce this sort of activity, since the volcano appears to be structurally stable and a flank eruption appears unlikely in the very short term, so that all magma will have to go to the summit craters. Many people here - including myself - have visions of the new cone standing like a twin next to its older "brother". Time will tell whether you will see, one day, a photo showing the twin Southeast Craters, and then, the younger of the two overtopping its older sibling ??? This is one of the most amazing things a volcanologist can dream of seeing before her or his eyes - the birth of a new volcanic mountain, right from the start.

Photo was taken from near the "Ripe della Naca", on the east-northeast flank of Etna, on the morning of 23 August 2011. Compare this to the images shown in the comments below.