Roundup of Global Volcanic Activity – New Activity for the week of 21 December-27 December 2016
Bezymianny | Central Kamchatka (Russia) : KVERT reported strong gas-and-steam emissions at Bezymianny during 16-23 December; a gas-and-steam plume drifted about 60 km SW on 18 December. A daily thermal anomaly was detected over the volcano. The Aviation Colour Code remained at Orange.
Bogoslof | Fox Islands (USA) : AVO reported that the explosive eruption at Bogoslof, which was reported by several pilots around 1530 on 20 December and produced an ash plume that rose to 10.3 km (34,000 ft) a.s.l., lasted about 30 minutes. The ash plume detached and dispersed S. AVO had raised the Aviation Colour Code (ACC) to Red and the Volcano Alert Level (VAL) to Warning, but since no further activity was detected or observed the ACC was lowered to Orange and the VAL was lowered to Watch. On 21 December periods of discrete earthquakes and continuous seismic tremor were recorded by instruments on nearby volcanoes. At 1610 an explosive eruption detected in satellite data and by seismic instruments on nearby islands again lasted about 30 minutes. An ash plume rose to an altitude of 10.7 km (35,000 ft) a.s.l. and drifted N. The ACC and VAL were raised to Red and Warning, respectively. Seismicity declined rapidly afterward and remained low; the ACC was lowered to Orange and the VAL was lowered to Watch. Strong continuous seismic activity started abruptly at about 1340 on 22 December.
AVO noted that the eruption had dramatically changed the island. Satellite images showed that a small new island had formed just offshore of the NE end of the main island, the previous shore and much of the NE side of Bogoslof Island adjacent to the new island had been mostly removed (and was likely the site of the new, underwater vent), and deposition of material had occurred on the W side of the island.
An explosion occurred at 0930 on 23 December. A Coast Guard ship in the vicinity reported ash emissions, lightning, and ejected lava and fragmented material. The ash plume rose to an altitude below 9.1 km (30,000 ft) a.s.l. Coast Guard observers noted that ash emission subsided around 1037. The ACC/VAL were raised to Red/Warning. On 24 December seismic unrest was periodically detected by nearby island networks, but levels were generally low. The ACC was lowered to Orange and the VAL was lowered to Watch. A period of tremor detected in the evening on 25 December may have been associated with a minor, low-level ash emission (below 3 km or 10,000 ft a.s.l.); several lightning strikes in the area were recorded. Lightning strikes, seismic data, and satellite images indicated a continuing eruption that began at 1405 on 26 December. An ash plume rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted WSW. The ACC/VAL were again raised to Red/Warning.
Ebeko | Paramushir Island (Russia) : KVERT reported that, according to observers in Severo-Kurilsk (Paramushir Island) about 7 km E, gas-and-steam plumes containing a small amount of ash rose from Ebeko to an altitude of 1.5 km (4,900 ft) a.s.l. and drifted 8 km N and NE on 17 and 20 December. Minor amounts of ash fell in Severo-Kurilsk during 18-22 December. Ash plumes rose as high as 2 km (6,600 ft) a.s.l. on 27 December. The Aviation Colour Code was raised to Orange (the second highest level on a four-colour scale).
Klyuchevskoy | Central Kamchatka (Russia) : On 26 December KVERT reported that a weak thermal anomaly over Klyuchevskoy had been detected after the April-November eruption. Gas-and-steam plumes sometimes contained small amounts of ash. The Aviation Colour Code was raised to Yellow (the second lowest on a four-colour scale).
Langila | New Britain (Papua New Guinea) : Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 21-24 December ash plumes from Langila rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted N, NW, S, and SE.