ETNA UPDATE, 23 MAY 2016, 17:30 UTC
During the past few days, two further eruptive episodes have taken place in Etna’s summit area. The first, in the early morning hours of 21 May 2016, occurred at the Voragine, which had been the site of two paroxysmal episodes on 18 and 19 May. This latest episode was preceded by modest Strombolian activity, which started around noon on 20 May, producing explosion noises audible in a vast area on Etna’s southern and eastern flanks. In the night, the activity gradually intensified, with explosions from two or three vents within the Voragine. Contemporaneously, renewed inflation of the summit area was recorded by a clinometer at Punta Lucia, to the northwest of the summit craters, as had happened also before the preceding paroxysms. Shortly after 04:00 local time (=UTC+2) and accompanied by a rapid increase of the volcanic tremor amplitude, the Strombolian explosions passed into pulsating jets of lava, launching incandescent bombs to a distance of about 1 km (to the southern base of the Bocca Nuova), and an eruption column was blown by the wind toward south-southeast.
The images recorded by the thermal monitoring camera at Monte Cagliato (EMCT, on the eastern flank of Etna) show that eruptive activity also occurred form a vent in the southern portion of the Northeast Crater, which had collapsed on 18 or 19 May. Visibillity was rather reduced due to weather clouds and further deteriorated in the final phase of the paroxysm. Yet it was possible to observe, during the climax of the paroxysm, that a fracture formed on the southeastern flank of the central cone, and in the “saddle” between this cone and the old cone of the Southeast Crater an effusive vent became active, which emitted a small lava flow toward the Valle del Leone. The photo above at left, courtesy of Alessandro Lo Piccolo, shows the explosive activity at the Voragine at right, and the little lava flow further left, which had advanced a few hundred meters. Again, lava erupted from the Voragine spread out over the floor of the nearby Bocca Nuova, already completely filled by the earlier lavas from the Voragine, and overflowed its western rim, feeding a multilobate lava flow that covered the lavas from the overflows on 18 and 19 May. The activity started to diminish around 05:00 local time, and was essentially over by 06:00.
Since the morning of 22 May, the eruptive vent formed o 25 November 2015 on the upper east flank of the New Southeast Crater cone was the source of a series of ash emissions, with plumes which in the absence of wind rose several hundred meters above the summit and then dispersed in the atmosphere. Some of these emissions produced small anomalies in the images of the thermal camera EMCT, pointing to the presence of hot material. On the evening of 22 May, Strombolian activity resumed at the Northeast Crater, which continued at flucutating rate and intensity through the night. The strongest explosions ejected incandescent bombs up to a few hundred meters above the crater rim, some of which fell onto the flanks of its cones. Today, 23 May, sporadic ash emissions continued from the vent on the upper east flank of the New Southeast Crater cone.
The activity of Etna is monitored continuously by the systems of video and thermal cameras, seismic stations and ground deformation.
May 24 , 2016. Etna , Sicily :
Source : INGV
Photo : Salvatore Lo Giudice