Report for Etna
INGV reported that during 3-9 December activity at Etna was characterized by gas emissions at the summit craters, with periodic Strombolian activity from vents in Bocca Nuova, Northeast Crater (NEC), and New Southeast Crater (NSEC). Strombolian explosions at the cone in NSEC became more frequent on 4 December. In addition, lava effusion became continuous with small overlapping flows traveling about 500 m down the E flank of the cone. Incandescent blocks generated by the lava flows rolled to the base of the cone, and occasional small collapses produced minor ash plumes. Strombolian activity and occasional ash emissions were characteristic of vents in the W part of Bocca Nuova’s (BN-1) crater floor. Gas emissions at Voragine Crater continued from a vent on the E rim of the crater, and Strombolian explosions were evident at NEC.
Report for Manam
The Darwin VAAC reported that on 6 December ash plumes from Manam were identified in satellite images rising to an altitude of 5.2 km (17,000 ft) a.s.l. and drifting SE. RVO noted that at 1215 on 8 December seismicity increased and indicated an eruption had begun, according to a news article. The eruption was characterized by forceful ash emissions, explosions that ejected lava fragments above the crater, and rumbling and roaring noises. Around 1300, based on pilot observations, information from RVO, and satellite images, large ash plumes rose as high as 15.2 km (50,000 ft) a.s.l and drifted E. Island reports noted that ejections of material ceased around 1900; audible noises ended around 1930. Satellite data indicated that ash from the high-altitude plume had begun to dissipate by 2020, and that on-going ash emissions rose to 8.2 km (27,000 ft) a.s.l. Island residents described heavy ashfall and that the sun was blocked by airborne ash, based on second-hand social media posts. News reports indicated that residents in Bokure and Kolang (NE and ENE flanks, respectively) had evacuated. Seismicity had declined by the end of the day. Dark ash plumes continued to be visible the next day, rising as high as 7.6 km (25,000 ft) a.s.l. and drifting E, though were less frequent.
Report for Krakatau
PVMBG reported that events at Anak Krakatau were recorded at 0711 on 7 December, at 1050 on 9 December, and 1413 on 10 December. The event on 9 December generated a dense black ash plume that rose 700 m above the summit and drifted N.
Report for Merapi
PVMBG reported that during 30 November-6 December the lava dome in Merapi’s summit crater grew at a rate of 2,200 cubic meters per day. By 6 December the volume of the dome, based on photos taken from the SE, was an estimated 344,000 cubic meters. White emissions of variable density rose a maximum of 150 m above the summit. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to remain outside of the 3-km exclusion zone.
Report for Dukono
Based on satellite data, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 4-11 December ash plumes from Dukono rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted mainly W, SW, and SE. The Alert Level remained at 2 (on a scale of 1-4), and visitors were warned to remain outside of the 2-km exclusion zone.
Report for Ibu
PVMBG reported that on 11 December an ash plume from Ibu rose to 1.8 km (6,000 ft) a.s.l., according to the Darwin VAAC. Weather clouds prevented views of the plume in satellite data. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.
Report for Mayon
PHIVOLCS reported that during 5-11 December white steam plumes periodically emitted from Mayon drifted mainly WSW. Crater incandescence was sometimes visible at night. A four-minute long event recorded by the seismic network began at 1224 on 9 December, and produced a grayish-brown ash plume that drifted W. The Alert Level remained at 2 (on a 0-5 scale) and PHIVOLCS reminded residents to stay away from the 6-km-radius Permanent Danger Zone and the 7-km Extended Danger Zone on the SSW and ENE flanks.
Report for Aira
JMA reported that at least two events at Minamidake crater (at Aira Caldera’s Sakurajima volcano) were recorded during 3-10 December, producing plumes that rose as high as 1.1 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).
Report for Ebeko
Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 30 November-7 December that sent ash plumes to 3.6 km (11,800 ft) a.s.l. Ash plumes drifted E, causing ashfall in Severo-Kurilsk on 30 November, and 1 and 4 December. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Report for Sheveluch
KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images on 30 November, 1 December, and 3-4 December. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Report for Veniaminof
AVO reported that on 2 December satellite data revealed that a third lobe of lava from the cone in Veniaminof’s ice-filled summit caldera had traveled a short distance down the SE flank of the cone. All three lobes produced sometimes voluminous steam plumes due to their interaction with the ice and snow. The eruption of lava continued during 4-5 December. Satellite and webcam data showed elevated surface temperatures. Steam plumes with possible diffuse ash were periodically identified in webcam and satellite images. On 6 December seismicity changed from nearly continuous, low-level volcanic tremor to intermittent, small, low-frequency events and short bursts of tremor, possibly indicating that lava effusion had slowed or stopped. Variable seismicity continued through 12 December, though there was no visual confirmation of lava effusion. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) and the Volcano Alert Level remained at Watch (the second highest level on a four-level scale).
Report for Kilauea
HVO reported that lava at Kilauea’s Fissure 8 cone was last visible on 4 September, signaling the end of the Lower East Rift Zone (LERZ) eruptive phase. Consequently, the end of the LERZ eruption also marks the end of the over-arching, on-going eruption at Kilauea that began at the East Rift Zone (ERZ) in 1983. That determination was made by HVO in part by using the Global Volcanism Program guideline that an eruption should be considered over on the date of the last eruptive activity, and when there has not been renewed activity in the following three months.
HVO noted that geophysical data continued to show magma being supplied to Kilauea, including the refilling of the middle ERZ, and reminded the public that Kilauea remains an active volcano. As of 4 December the Volcano Alert Level remained at Advisory and the Aviation Color Code remained at Yellow.
Report for Turrialba
OVSICORI-UNA reported continuing activity at Turrialba during 5-11 December. A minor emission from the vent was visible on 5 December, and an ash emission drifted S the next day. An event at 0749 on 8 December produced an ash plume that rose 500 m and drifted NW. Emissions of ash, steam, and gas rose as high as 1 km on 9 December and caused ashfall in areas of Valle Central. On 10 December diffuse emissions were periodically observed during periods of clear viewing. That same day ash fell in Moravia (31 km WSW) and Santa Ana, and residents of Heredia (38 km W) noted a sulfur odor.
Report for Sabancaya
Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that an average of 17 explosions per day occurred at Sabancaya during 3-9 December. Long-period seismic events were recorded, and hybrid earthquakes were infrequent and of low magnitude. Gas-and-ash plumes rose as high as 3 km above the crater rim and drifted 40 km E and SW. MIROVA detected seven thermal anomalies, and on 6 December the sulfur-dioxide gas flux was high at 3,600 tons per day. The report noted that the public should not approach the crater within a 12-km radius.
Report for Nevados de Chillan
ONEMI and SERNAGEOMIN reported that at 0313 on 7 December an explosion at Nevados de Chillán was recorded by the seismic network, and produced a high-temperature emission of gas and tephra recorded by a webcam. The Alert Level remained at Orange, the second highest level on a four-color scale, and residents were reminded not to approach the crater within 3 km. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for the communities of Pinto, Coihueco, and San Fabián.
Report for Copahue
The Buenos Aires VAAC reported that on 6 December a pilot observed ash from Copahue at an altitude of 3 km (10,000 ft) a.s.l. Ash was not visible in satellite data and could not be confirmed by unavailable webcams. An ash emission observed by a pilot and identified in satellite images on 7 December rose to 3 km (10,000 ft) a.s.l. and drifted SW.