Etna volcano illuminates Sicily's night sky during its 16th paroxysmal eruptive episode in a row
Wed, 24 Mar 2021, 07:1707:17 AM | BY: T
Lava fountain during the peak of the lastest paroxysm at Etna's New SE crater (image: Giorgio Costa / facebook)
Thermal view of the lava fountain (image: thermal webcam of INGV)
Current tremor signal (image: INGV Catania)
It may have come after the longest-yet interval, 4.5 days, almost double the previous average, since the previous lava fountaining episode, but it made up for it by lasting more than twice as long: The 16th paroxysm from Etna's New SE crater in only 5 weeks time, which had started in the late evening, lasted through the whole night and essentially still goes on!
Ongoing activity this morning (image: LAVE webcam)
After being more or less completely silent for several days, the New SE crater started again strombolian activity from around 8pm local time, and this activity quickly began to increase as we had already observed in our previous updates yesterday evening.
From around 11 pm, the explosions merged into sustained lava fountaining, from which point on it the eruption is commonly called a paroxysm. Instead of its peak phase lasting only 1-2 hours as during most previous eruptions, it continued for almost 5 hours! Only after 3:30 am, the intensity of the eruption dropped a bit. However, again different from most previous episodes, the intensity of activity did not drop quickly to low levels, but has since remained at still high levels.
As of the time of this post, around 7 am, the eruptive is still going on strongly, with vigorous strombolian explosions from the New SE crater and continued lava effusion.
Different from previous paroxysms as well, the lava fountains seemed not to have reached the same great heights lava effusion was much less intense: Although rather broad, the active lava flow traveling east from the active crater as usual has only reached approx. 1 km length and its front is still only at the upper rim of the rim of the Valle del Bove at around 2900 m elevation.
The volcano observatory reported that the associated eruption column rose to approx. 6 km altitude and drifted South-South East, causing ash fall in Catania. The airport had to cancel a few of the night-time flights, but seems to be back in normal operation.
Hot avalanche observed
At 03:37 local time, a pyroclastic flow was observed on its surveillance cameras, INGV Catania reported. It was also confirmed by personnel present on site.
The flow can be seen in the recorded webcam video (scroll back): suddenly, part of the lava flow and accumulated hot material mobilizes into an avalanche on the eastern fissure and quickly descends the flank, reaching more than 1 km length.
Why was the lava flow comparably short?
Why there is less lava that went into the flow although lava fountaining lasted longer is not easy to say. It could be that either total volume of lava erupted was indeed lower despite the longer fountaining phase. This seems to be the most likely cause, also considering that from available imagery, it seems that the lava fountains although still impressive with approx. 3-500 m height, did not reach the same heights of 1000 m or even more sometimes observed during previous paroxysms. The same seems to be true for the eruption column.
In other words, while it lasted longer, the output rate was lower, so that the total volume was similar or even less. The other, but less likely explanation for less volumnious lava flows this time could be that most of the lava erupted did not go into the flow, but was fragmented into ejecta that landed around the cone or went up into the eruption column. This would imply a higher gas content of the erupted magma, which in turn actually should have caused a higher eruption column (and higher fountains), so we probably can discard this as the cause, but without data from analysis of the lava it can only remain a speculation.
Image credit lava fountain: Giorgio Costa (facebook)
Wed, 24 Mar 2021, 06:00
Etna Volcano Volcanic Ash Advisory: ERUPTION AT 20210324/0245Z ONGOING ERUPTION WITH ASH EMISSION to 20000 ft (6100 m)