From 1 to 4 craters in only 100 years
Mount Etna is the largest active volcano in Europe, with a volcanic surface of 1250 square kilometres and a diameter of 45 km from east to west and as much as 65 km from north to south. The volcano has a unique and distinctive shape, not only because it shows some signs of its evolutionary phases from different sides, but especially because of the large depression on the eastern side: the Valle del Bove.
Today, at its top, there are three clearly distinguishable cones, two of which were formed within only a hundred years: the Northeast Crater (1911), the Voragine (1945) and Bocca Nuova (1968) craters, which are inside the old central crater, and the Southeast Crater (1971), the eastern part of which is made up of the material that came out from the conduit of the New Southeast Crater.
A little over a hundred years ago, until 1911, there was only one central crater on the summit of Etna, with a large cone 250 m high and an opening over 500 m in diameter; it rose between the Piano delle Concazze to the northeast and the Piano del Lago to the south. But from 1911 onwards, nothing was the same.
In the spring of 1911, several fractures formed along the northeast rift between 2000 m and 3000 m above sea level, and on 27 May a large fracture opened to the northeast of the central crater at about 3100 m. The following weeks were marked by mild volcanic activity, which began to increase slightly in August.
It was only from 9 September of the same year that, together with the occurrence of intense seismic activity, strombolian activity also began, initiating the formation of the new cinder cone. The material that fell back down from the two-kilometre-high lava fountains began to form the structure of the new, independent cone.
This particularly violent phase fortunately lasted only 13 days and was accompanied by the emission of large amounts of ash from the central crater and the opening of a myriad of fractures scattered along the Pernicana Fault or the Northeast Rift. At these fractures, 16 mouths opened within only two days, on 10 and 11 September, on 12 September as many as 30 were active at the same time, and surveys after the end of the eruption counted about a hundred, grouped mainly along seven fault lines.
On 22 September, the eruption stopped abruptly, all activity ceasing abruptly, indicating the risk of a dangerous and violent recurrence. However, it was not until 3 May 1923 that the Northeast Crater made the inhabitants of Etna’s northern slope tremble again, with an eruption that again opened several fractures along the axis of the Northeast Rift and produced dangerous lava flows that stopped at 600 m altitude after destroying some parts of Linguaglossa.
In 1950, the Northeast Crater began to suffer collapses and another cone began to form inside it.
In 1960, a particularly lively phase began, forming several cones along its flanks, culminating in the formation of Crater Northestino in 1970. Through the various phases of growth and the deposition of fallout material from strombolian activity, the North-East Crater gradually reached a perimeter of 800 m and a height of 3345 m above sea level, thus becoming Etna’s highest point in 1978.
In recent decades, it has often been noted for its characteristic plume, but it has not been particularly active – apart from the 2016 eruption that caused the conduit blockage and collapse of the southern rim.
In 2017, the bottom of the crater subsided, reopening the vent and causing its characteristic smoke to rise again.
Until 2021, the north-eastern crater was the highest of Etna’s main craters, but due to a series of collapses of its rim in recent decades it now measures only 3324 m above sea level.