Etna volcano (Italy): swarm of tiny earthquakes under eastern flank
The depths of the quakes are mostly between 10-20 km in the lower crust where they might - or might not - indicate small events related to magma storage at lower reservoirs. It seems unlikely this will directly affect or translate into changes of the surface activity of the volcano in any near future. This is, at least, as long as the earthquakes are small as they are and don't approach shallower levels.
New SE crater calms down again, remains weakly active
At the surface, the volcano has remained quite calm. The recently observed trend of increasing activity at the New SE crater has reversed again. During the past 36 hours, there were only sporadic ash emissions with weak glow visible sometimes at night, suggesting that explosions are only small and occurring deep inside the vent, without ejecting glowing material above the crater rim.
After almost 4 weeks of calm, New SE crater is showing signs of life again!
Two strong strombolian explosions occurred in the night of 24-25 April and in the morning of 26 April at the Southeast Crater, followed by weak glow and smaller occasional explosions since last evening.
It is too early to predict whether this activity will continue and possibly increase towards another strong eruptive phase with lava fountaining (or paroxysm), but it might very well do so. Volcanic tremor has been showing a gradual slow increase during the past two days.
According to volcanologist Dr. Boris Behncke from INGV Catania, ground deformation is still extremely low, compared to what was seen between the period of inflation (reflecting magma charging) during last autumn-winter and the deflation caused by the series of paroxysms in February-March.
Only Etna will know what is coming up next!
17th paroxysm of Etna - spectacular video
This eruptive episode had been very remarkable, even for Etna standards, and for several reasons:
First, while its intensity at peak phase may not have quite reached the same values as many of the previous 16 episodes since mid February, it lasted significantly longer than any other, with about 12 hours of lava fountaining, and a very long build-up and declining phases, making the whole episode lasting almost two days!
Secondly, the opening of a new effusive vent at the southern base of the cone in the morning of 31 March also marked a significantly different behavior than observed previously. As to its causes, we can only speculate that the uppermost parts of the conduit system had become sufficiently unstable by now, so that when pressure in the upper conduit increased, it opened a fracture at a lower point, at the southern base of the cone, and allowed some of the magma to find an easier there.
This would explain why the intensity of the eruption later at the summit vent was a bit lower,- some of the magma was "diverted" just before reaching the summit.
Local Etna specialist filmmaker Michele Mammino took some of the most remarkable videos of this eruption, in particular close-up shots of the new fissure vent that was active at the southern base of the New SE crater. Enjoy:
It is worth mentioning that during the whole time of the eruptive phase at the New SE crater, the other summit vents continued their intermittent mild strombolian activity.
Eruptive episode still going on strong
The National Institute of Geophysics and Volcanology (INGV) in Catania reported that strombolian activity at the SE Crater passed to sustained lava fountains from around midnight, meaning that these now have been continuing for more than 9 hours! The eruption column has been rising to an altitude of approx. 7 km (20,000 ft) and dispersing towards the SSW, where it is raining black lapilli and volcanic sand now.
The effusive activity from the new fissure vent at the southern base, which had been active since yesterday morning continues to produce weak explosive activity and to feed a lava flow that flows SSE into the western sector of the Valle del Bove.
A second lava flow began as overflow from the eastern summit vent of the crater shortly after midnight, in tandem with the onset of lava fountains at the summit, and is traveling eastward down into the upper part of the Valle del Bove.
Finally, while all this action is happening at the SE crater, the eruptive activity at the other summit craters remains unchanged as if their conduits were completely independent from the one SE crater's.
17th lava fountaining episode at New SE crater started
While activity from the the new eruptive vent that opened this morning at the southern base of the SE crater continued to increase, feeding lava flows, in particular one directed south and southwest towards the Valle del Bove, the summit vent has been activated again to join the action. Its activity began with smaller explosions that quickly grew in intensity and now started to generate lava fountains, constantly increasing in height and likely already surpassing 200 meters as of now.
Resulting from this, a significant ash plume began to rise above the crater and is drifting in southerly directions. The volcano observatory in Catania raised the aviation color code to RED due to these strong ash emissions, likely to increase further in the coming hours.
The 17th paroxysm of Etna's New SE crater since mid February has started. How long it might last could range from few to many hours.