Build-up and start of the eruption
For about 10 days preceding the eruption, the New SE crater had shown sporadic strombolian activity at fluctuating levels. Tremor had been fluctuating with a slightly increasing tendency in accordance.
The onset of the eruption was in the late afternoon of 8 Feb, when strombolian bursts became more frequent, and the tremor signal started to rise gradually.
Evolution of the paroxysm during 8-9 February
Strombolian explosions were continuous since about 17h00 local time, and gradually merged into increasing lava fountains, accompanied by a slowly rising volcanic tremor signal. The eruption was fed by several vents along the fissure cutting through the cone. Low but sustained lava fountaining seems to have started sometime between 21 and 23 h local time. At about 21h00, a lava flow started to be visible issuing ESE direction from the SE notch of the crater. By 22h30, the lava flow had reached the slope break at the western rim of the Valle del Bove and started to descend there, split into at least 2, probably more branches.
At about 23 h local time, taller lava fountains were visible from the webcam. The peak phase of the eruption lasted much longer than previous episodes. It began around 01 am and lasted for about 5 hours until around 6 am near dawn. It produced tall lava fountains reaching an estimated 500 m or more judging from the webcam pictures, and a tall plume of steam and ash rising several kilometers and drifting SW.
New SE crater paroxysm on 8-9 February (nr 20)
Another spectacular paroxysmal eruption occurred from Etna's New SE crater during the night of 8-9 February, marking the 20th such episode since 2011 or the second in 2012. The eruption followed an approximate 10 day period of intermittend strombolian activity which increased during the afternoon of 8 February and reached its peak with tall lava fountains after midnight, and large lava flows into the Valle del Bove.
The eruption produced a tall plume of ash which drifted to the SW and forced the cancellation of most early flights in and out Catania airport. Later in the morning, after the end of the eruption and the ash plume had dissipated, the operations resumed back to normal.
The eruption was one of the most intense and longest in the series.
The following is a preliminary interpretation of the temporal evolution of the eruption, based on regular snapshots (see pictures below) taken from various webcams (notably, the radiostudio7, etnaweb and INGV webcams, in comparison with the volcanic tremor signal).
around 07h30 local time: eruption ends
The eruption has ended, somewhere around 07h30, following a steep decrease of lava emission corresponding to the steeply decreasing tremor signal.
Broad (= long duration) tremor peak of the eruption
06h35 local time: eruption decreases, but still lava fountains 2-300 m high
Volcanic tremor is sharly dropping now, but lava fountains are still impressive. Probably, the eruption will still continue for a while and end, abruptly or with a long tail, we cannot say right now. We end our "webcam reporting" at this point.
06h20 local time
06h10 local time: eruption still going on, very tall lava fountains
06h00 local time: eruption still strong, but continues to decrease slowly
It appears that the peak of the eruption is over at this time, as the visible fountains and their intensity have decreased a bit, along with the tremor curve which now has started to descend.
In most other paroxysms, the end was a very shap drop in activity, which could happen now as well. On the other hand, given the very slow build-up and long duration of the main phase, it might be a slow decrease this time.
05h40 local time: eruption still strong, but seems to start decreasing
05h25 local time: eruption at full force
05h05 local time: eruption still growing
04h45 local time: eruption increases more
The eruption picked up again and is still getting stronger it seems. Lava fountains are probably higher than 500 m now.
04h20 local time: eruption stays very vigorous
03h50 local time: eruption still going on strong, but slight decrease
03h25 local time: eruption at its peak
02h45 local time: eruption continues and even increases
02h15 local time
01h50 local time: eruption increases to near peak intensity
The lava fountains are now probably 300-500 m tall. Steam generated from the lava flow melting snow downslope in Valle del Bove begins to drift through the view to the lava fountains from the Belvedere webcam.
01h18-01h35 local time: 300 m lava fountains
00h55 local time: eruption gains strength again
00h40 local time: eruption briefly decreases
00:10 local time: fountaining starts
The eruption seems to have entered its peak phase, although the tremor amplitude is still low compared to previous paroxysms. Judging from the webcam images, lava fountains are probably 200-300 m high.
23h35 local time: eruption increases
In the last half an hour, the eruption has increased significantly in strength. Several vents can be located from the webcam images, and lava fountains are probably reaching roughly 200 m already.
23h05 local time: lava fountains start rising
22h55 local time
22h30 local time
22h05 local time: continuous explosions
21h50 local time
17h10 - 21h13 local time
During the 3 hours between 17h00 and 20h00, the tremor doubled from about 4 (left picture) to 8, and strombolian activity had become vigorous and continuous (right picture).