December 04 , 2015. EN. Etna, Ertaale , Zhupanovsky .
December 04 , 2015.
Etna, Sicily :
Update ETNA, Dec. 3, 2015, at 09:30 UTC
After a progressive intensification on the evening of December 2, 2015, the eruptive activity in the crater of Voragine (often also called « Central ») of Etna, peaked in the early hours of December 3, but in a short paroxysm very violent, with a large fountain and lava eruption column of several kilometers high. The excellent weather conditions have allowed the observation of the event with the visual surveillance cameras and thermal network of the INGV–Osservatorio Etneo, and from many places around the volcano.
The highlight of the paroxysm occurred between 2:20 and 3:10 UTC (local time = -1) when a sustained lava fountain reaches a height of over 1 km. Some incandescent jets of matter reached the height of 3 km above the summit of the volcano. The pyroclastic cloud of material was moved by the wind to the north, causing ash fall on the villages of Linguaglossa, Francavilla di Sicilia, Milazzo, Messina and Reggio Calabria. At dawn, the eruptive activity had almost ceased, although some weak ash emissions still occur since the Voragine and the Northeast crater and the small pits crater that opened recently on the upper side of the New Southeast Crater.
The paroxysmal event last night was among the most violent of Etna in the last two decades. The Voragine was the same place of the two particularly intense paroxysms of July 22, 1998 and September 4, 1999, with similar characteristics to the paroxysm of 3 December 2015. Both have produced lava fountains, which in the case of 4 September 1999, had risen to 2000 m high and eruptive columns (that of July 22, 1998 reached a height of 12 km above the sea level) with abundant pyroclastic material relapse in Southern sector of the volcano in the first case, and the eastern sector in the second.
Even in the past, Voragine was honored for its ability to produce exceptionally violent paroxysms, as in February 1947, July-August 1960, in August 1989.
A more detailed report will be published shortly on this site.
Source : INGV
Photo : Turi Caggegi , Alessandro lo Piccolo ( tout droits réservés), La Repubblica.
Ertaale , Ethiopia :
Reproduction « in extenso« of the report published by T. Pfeiffer / VolcanoDiscovery.
During our recent volcano expedition to the Danakil depression, we have observed the active lava lake of Erta Ale – which had been at very high level just a few meters before overflowing – for three continuous days (19-21 November 2015).
Upon our arrival on the morning of the 19th, the lava lake was only about 2-3 m below us. Our local guide explained that the lava lake had been very active in the past few weeks and risen so highly for the first time since its overflow in late 2010. Standing on the rim of the active vent within the large Erta Ale caldera, we observed a second terrace no more than 1 m below us. The fresh black pahoehoe lava of this level had been erupted and solidified a few days before.
Midday 19 November, the surface of the boiling lava lake was just 1.5 m below this second terrace. Throughout that day, however, the lava lake was rising steadily and had almost reached the height of the second terrace – but then stabilised at a mere 30 centimeters below the rim of the second terrace. A few active lava fountains at the edge of the lake periodically splashed fresh lava onto the second terrace,
with some droplets reaching the outer rim of the vent. Pele´s hair was continuously formed and blown around. Zigzag patterns broke up the lake´s black crust, pushing it to the lake´s edges where they were recycled into the molten lava. Degassing in the form of Strombolian activity and short-lived fountains was sometimes so intense that lava spattering could even be seen from the old caldera ridge where we had our camp.
Overflowing of the second terrace never occurred and by the morning of the 20th November the lava lake had actually dropped a few metres. Activity had thereby changed from Strombolian explosions and short-lived fountains from a few locations along the lava lake´s edge, to a seemingly quiet surface that once every 5-10 minutes would suddenly form a central depression before lava rose up in a large lava bubble that exploded, with recycling of the cooled crust in a series undulating lava waves (similar fluid dynamics as when one drops a pebble in a calm water body).
During 20 and 21 November, the lava lake mainly showed this latter, large exploding bubble activity with only minor Strombolian activity or fountaining along the lakes edges. The level would rise and fall relatively quickly, between 5 m and 1 m below the edge of the second terrace. On the evening of the 21st, we witnessed how the lava lake rapidly rose about 3m, starting from 5 m below the second terrace. This
fast change in the lava lake´s surface level coincided with a different activity, namely fresh red-hot lava seeping up along the zigzag cracks and overflowing a large part of the thin crust in a matter of seconds.
The fumarole fields along the rim of Erta Ale´s second active vent continue to be active, with the centrally located tall hornito, built during the 2012 magmatic eruption there, also still degassing.
Source : T Pfeiffer / Volcanodiscovery
Photos : Ingrid/ Volcanodiscovery
Elevation 2899 m
Based on satellite images, KVERT reported that on 28 November ash plumes from Zhupanovsky rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. and drifted 285 km E. The Aviation Color Code was raised to Orange. IVS FED RAS (Institute Volcanology and Seismology Far East Division of the Russian Academy of Sciences) observers noted an ash explosion at 0356 on 1 December; the Tokyo VAAC reported that the resulting ash plume rose to an altitude of 9 km (29,500 ft) a.s.l. and drifted 60 km SE.
The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated volcanic complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene, the fourth is Holocene in age and was the source of all of Zhupanovsky’s historical eruptions. An early Holocene stage of frequent moderate and weak eruptions from 7000 to 5000 years before present (BP) was succeeded by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 years BP. Historical eruptions have consisted of relatively minor explosions from the third cone.
Source: kamtchakan éruption volcanique Response Team (KVERT) , GVP.
Photo : S. Samoilenko, IVS FEB RAS ( 2013)