Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week 24 November – 30 November 2021

Aira ; Kyushu (Japan) : JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 22-29 November. An eruptive event at 1509 on 25 November generated a plume that rose 1 km above the crater rim. The sulfur dioxide emission rate was slightly high at 1,200 tons per day on 26 November; sulfur dioxide emissions had been generally high since late September 2020.

Bagana ; Bougainville (Papua New Guinea) : The Darwin VAAC reported that on 27 November ash plumes from Bagana rose to 2.1 km (7,000 ft) a.s.l. and drifted NW based on satellite and wind model data.

Ebeko ; Paramushir Island (Russia) : On 26 November KVERT lowered the Aviation Color Code for Ebeko to Yellow (the second lowest level on a four-color scale), noting that a thermal anomaly was last identified on 25 October and eruptive activity was last recorded on 9 November. Gas-and-steam emission continued to be visible.

Etna – Sicily (Italy) : INGV reported that gas emissions from Etna’s summit craters were visible during 15-21 November, though weather clouds sometimes prevented webcam observations. At 1116 on 20 November an explosion at Northeast Crater (NEC) produced diffuse ash-and-gas plumes that quickly dissipated near the summit.

Great Sitkin – Andreanof Islands (USA) : According to AVO satellite images acquired on 23 November showed that lava effusion at Great Sitkin continued, though at a low rate. Lava continued to fill the summit crater and the flows on the flanks advanced short distances. During 24-30 November seismicity remained slightly above background levels. Elevated surface temperatures were periodically detected.

Grimsvotn – Iceland : On 24 November Icelandic Meteorological Office (IMO) reported that the ice sheet in Grímsvötn’s caldera had subsided 60 cm in the previous few days and the rate of subsidence had accelerated in the last day. By 29 November the ice had sunk a total of 5 m and by 1 December the subsidence totaled 10 m. Data indicated that water had likely begun exiting the caldera and will result in a jökulhlaup (glacial outburst flood) that will cause flooding conditions in drainages. Water levels in the Gígjukvísl drainage rose overnight during 30 November-1 December.Roads, including several national highways, have been cut by flooding or landslides. Wide areas of agriculture along with livestock have suffered damage.

Katmai – United States : AVO reported that on 25 November strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes blew unconsolidated ash SE over Shelikof Strait and Kodiak Island at an altitude up to 1.5 km (5,000 ft) a.s.l. The ash was originally deposited during the Novarupta eruption in 1912.

Kilauea – Hawaiian Islands (USA) : HVO reported that the summit eruption at Kilauea continued at a vent in the lower W wall of Halema`uma`u Crater during 24-30 November. The vent contained ponded and sometimes spattering lava that fed the lake through the E part of the W wall cone. The size of the active part of the lake varied, and lava periodically oozed from the cooler, outer margins of the lake onto the lowest of the exposed down-dropped caldera floor blocks. Earthquake activity remained below background levels and volcanic tremor was elevated. The sulfur dioxide emission rate had averaged 3,000 tonnes per day in recent weeks; on 23 November the rate was higher at 6,400 tonnes per day and on 29 November it was below the average at 1,200 tonnes per day.

La Palma – Spain : The eruption at La Palma continued during 24-30 November, characterized by Strombolian explosions and lava fountaining/jetting from multiple existing and new vents, advancing and sometimes branching lava flows, and daily ash emissions. The eruption began on 19 September and had been active for 70 days by 28 November. Volcanic tremor levels were low, though during 28-29 November levels fluctuated and were sometimes intense. Seismicity persisted at variable but elevated levels, with earthquake locations distributed at depths of 10-15 km and 30-40 km. Deeper seismicity decreased to low levels by 27 November while mid-level seismicity intensified through the week. The largest earthquake was a M 5 recorded at 0935 on 29 November at a depth of 36 km. A M 4.2 earthquake at a depth of 13 km was the largest event at mid-levels since the eruption began. Several vents in the main cone continued to effuse lava, eject tephra, and emit ash-and-gas plumes. Lava moved W through pre-existing lava channels, lava tubes, over older flows, and over new ground, increasing the flow field that consists of overlapping flows (numbered 1-11) and two lava deltas. During 23-25 November flows 4, 5, and 7 at the N end of the flow field continued to widen and advance, filling in gaps between the flows, and fed the N delta. Flows 1, 2, and 9 minimally fed the S delta. There was also an increasing number of active flows on the flow field as lava overflowed some channel margins or broke out of tubes. At around 0900 on 25 November the lava effusion rate increased at main crater vents, and around 1100 two small E-W fissures opened less than 1 km S of the main cone. The easternmost vent produced a fast-moving lava flow that traveled along the S margin of flow 10 and around the S side of Montaña Cogote. The flow advanced through the Las Manchas cemetery and inundated parts of a solar power plant; the newly covered areas were part of the exclusion zone and had already been evacuated. The flow rate slowed to about 25 m per hour and joined flow 11 by 26 November. An overflow of lava SW of flow 3 produced a small branch oriented laterally the flow margin. Flow 7 widened during 26-27 November as it continued to be fed. New vents opened on the NE flank of the main cone at around 0300 on 28 November, producing fluid lava flows that traveled N and NW through the Tacande area and crossed the LP-212 road. The opening of the new vents was followed by landslides on the NW flank of the cone. In a video taken at 1145 lava fountains rose from one of the vents while another ejected tephra. Dense billowing ash plumes rose from the main crater. Video taken at 1050 on 29 November showed lava flows transporting large blocks downslope. Another video showed lava flowing at a rate of about 1 m per second. By noon the vents in the main cone became notably less active and remained only intermittently active through 30 November. Several streams of lava from the new vents continued to advance NW and then W along older flows and split into two branches. One branch traveled through tubes and fed flows 4, 5, and 7 between Montaña de Todoque and Montaña de La Laguna and the other descended towards flow 8 (the most northern flow). Flows inundated previously untouched forest and agricultural land. By 30 November the width of the flow field had grown to 3.35 km and lava covered an estimated 11.34 square kilometers. The number of people that had evacuated and were staying in hotels had increased to 537. Gas and ash emissions again impacted island residents. Suspended ash and high concentrations of volcanic gases triggered a few air-quality alerts mostly affecting the W part of the island; authorities warned residents of some affected areas to stay indoors. Essential personnel were occasionally barred from entering the exclusion zones to irrigate crops and remove ash from streets and buildings. Heavy rains during 25-26 November triggered warnings from authorities to stay away from steep slopes and drainages due to the possibility of lahars. Ash plumes rose as high as 4.8 km and drifted E during 24-26 November, and continued to deposit ash at La Palma airport. By 27 November winds had shifted and the ash at the airport had been removed, allowing it to open for the first time since 20 November. Ash plumes rose 1.4-3.5 km and drifted SW and SSW during the rest of the week. Sulfur dioxide emissions continued an overall downward trend during 23-26 November, though heavy rain sometimes prevented ground-based measurements. The trend was broken on 27 and 28 November with values of 30,000-49,999 tons per day, characterized as “very high.” During 29-30 November emission values were “high” or between values of 1,000 and 29,999 tons per day.

Lewotolok – Lembata Island (Indonesia) : PVMBG reported that the eruption at Lewotolok continued during 24-30 November. Daily white-and-gray ash plumes rose as high as 1 km above the summit. Crater incandescence was visible each day, with eruptions accompanied by rumbling and roaring sounds. Incandescent material was ejected 300-500 m E and SE from the vent during 24-25 November.

Merapi – Central Java (Indonesia) : BPPTKG reported no notable morphological changes to Merapi’s SW lava dome, located just below the SW rim, or the dome in the summit crater during 19-25 November. The estimated dome volumes remained stable at 1.61 million cubic meters for the SW dome and almost 2.93 million cubic meters for the summit dome. As many as 110 lava avalanches traveled a maximum of 2 km SW. One pyroclastic flow traveled 1.8 km SW on 20 November.

Nyiragongo – DR Congo : OVG reported that active vents on the crater floor of Nyiragongo were seen ejecting spatter on 27 November.

Pavlof – United States : AVO reported that the eruption at Pavlof continued during 23-30 November, focused at a vent on the upper SE flank. Low lava fountaining that had begun on 14 November continued to construct an unstable cone over the vent. Hot rubbly lava flows from the cone traveled a few hundred meters down the flanks, melting snow and ice that resulted in narrow lahars which traveled several kilometers down the flanks; satellite data from 25 November showed a new debris flow extending downslope from the end of the lava flow. Seismicity remained elevated; a few small explosions were detected during 24-26 and 28-30 November. Elevated surface temperatures were periodically observed in satellite data, though cloud cover sometimes prevented observations.

Reventador – Ecuador : IG reported that a high level of activity continued to be recorded at Reventador during 24-30 November. Gas-and-ash plumes, often observed multiple times a day with the webcam or reported by the Washington VAAC, rose higher than 1.3 km above the summit crater and drifted mainly NW, W, SW, and S. Crater incandescence was visible nightly, and incandescent blocks were observed rolling 400 m down the flanks in all directions on most nights.

Sangay – Ecuador : IG reported that thermal anomalies, persistent at Sangay since July, suggested continuous emission of lava flows and hot pyroclastic material from summit crater vents. The SE drainage, which had been scoured and widened by persistent pyroclastic flows during August 2019 to March 2020, had only widened from about 600 m to about 650 m during March-October. An increased number of explosions and an inflationary trend were recorded during the previous few weeks. Strombolian activity began to dominate the eruptive style in July, though on 17 November the number of explosions increased to two per minute and remained at that level at least through 23 November. Most of the explosions were small and were recorded both by the seismic and acoustic networks. Though slight inflation began to be detected in June 2021 the trend was more pronounced in recent weeks. InSAR satellite data showed an inflationary trend of up to 5 cm per year all around the volcano except the E flank between 5 January 2020 and 13 November 2021. The sulfur dioxide emission rate had remained stable and low since June, with values less than 1,000 tons per day. Daily ash-and-gas plumes were identified by the Washington VAAC or in IG webcam views during 23-29 November. The plumes rose 970-2,100 m above the volcano and drifted NW, W, SW, and S. Daily thermal anomalies over the volcano were often visible in satellite data. Strombolian activity at summit vents and SE-descending lava flows were visible during 23-24 November. A new vent was possibly identified on the upper W flank. Two lahars were detected by the seismic network on 25 November.

Semisopochnoi – Aleutian Islands (USA) : AVO reported that eruptive activity at Semisopochnoi’s North Cerberus crater continued during 24-30 November. Daily minor explosions were detected in seismic and infrasound data. Weather clouds obscured satellite and webcam views of the volcano on most days; small ash plumes rising no higher than 3 km (10,000 ft) a.s.l. were sometimes visible during breaks in the cloud cover but were likely emitted daily.

Sheveluch – Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 19-26 November.

Stromboli – Aeolian Islands (Italy) : INGV reported that during 15-28 November activity at Stromboli was characterized by ongoing explosive activity from five vents in Area N (North Crater area) and four vents in Area C-S (South-Central Crater area). Explosions from Area N vents (N1 and N2) averaged 6-17 events per hour; explosions from two vents in the N1 vent ejected lapilli and bombs 80 m high and explosions at three N2 vents ejected material 80-150 m high. Spattering at N2 was sometimes intense. No explosions occurred at the S1 and C vents in Area C-S; explosions at the two S2 vents occurred at a rate of 4-9 per hour and ejected coarse material as high as 80 m. Drone footage acquired on 20 November captured two C-S vents ejecting shreds of lava and one emitting gas. A 60-m-line of fumaroles, oriented NNW, were situated on the Sciara del Fuoco, down-flank of Area N. During the morning of 21 November intense spattering occurred at a vent between N1 and N2 produced a rheomorphic lava flow, formed by the accumulated spatter, on the upper middle part of the Sciara del Fuoco. At 0751 on 25 November lava blocks originating from a hornito in the N2 area began rolling downslope. Within a few hours a lava flow was visible in the same area; blocks from the end of the flow descended the Sciara del Fuoco, reaching the coastline. The rate of lava effusion varied during 25-26 November; the flow had begun cooling by the evening of 27 November.

Suwanosejima – Ryukyu Islands (Japan) : JMA reported that during 22-29 November about 41 explosions at Suwanosejima’s Ontake Crater produced eruption plumes that rose as high as 2.7 km above the crater rim and ejected blocks 500-800 m from the crater. Crater incandescence was visible nightly.

Yasur – Vanuatu : The Vanuatu Meteorology and Geohazards Department (VMGD) and the Wellington VAAC reported that multiple gas-and-ash emissions at Yasur were visible in webcam images on 27 November rising 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifting W. Weather clouds prevented satellite observations of the emissions.

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