A small amount of ash began to be visible in gas-and-steam emissions at Klyuchevskoy beginning at 1020 on 24 October, prompting KVERT to raise the Aviation Color Code to Yellow (the second lowest level on a four-color scale). Later that day video images showed an ash plume rising as high as 6 km (19,700 ft) a.s.l. and drifting 40 km NE. The Aviation Color Code was raised to Orange. KVERT and the Tokyo VAAC noted that during 25-28 October ash plumes rose to 5.5 km (18,000 ft) a.sl. and drifted 15-20 km SE, E, and NW. A weak thermal anomaly over the volcano was identified on 18 and 24 October.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

A large shallow earthquake at Kuchinoerabujima was recorded at 2133 on 27 October, prompting JMA to raise the Alert Level to 3 (the middle level on a scale of 1-5) within a few hours. The report also stated that the number of volcanic earthquakes had increased on 18 October. A large earthquake was also detected on 18 October but had occurred at a slightly deeper location (below the W part of Shindake Crater) than the 27 October event.

Source: Japan Meteorological Agency (JMA)

AVO reported that after a small explosion at Pavlof was recorded on 19 October and before 25 October clear satellite and webcam views did not show any deposits associated with the event. Weakly elevated surface temperatures and a small steam plume were occasionally visible. No other activity was detected during 26-29 October. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Pilot and local observations as well as webcam views all indicated that the incandescence at Shishaldin’s summit crater was from low-level Strombolian activity during 21-22 October. Seismicity and infrasound signals were consistent with low-level eruptive activity, and a steam plume was persistent. By 23 October lava had filled the crater and during 23-24 October overflowed the N crater rim. A 200-m-long lava flow on the N flank melted snow and caused a lahar which traveled 2.9 km and stopped at about 1,230 m elevation. A smaller lava flows caused a 1-km-long lahar to descend the NE flank. Spatter accumulated around the crater rim and melted snow. On 25 October AVO noted that trace ash deposits had extended at least 8.5 km SE.

Low-level eruptive activity continued during 26-29 October. Seismicity remained elevated, with periods of high-amplitude tremor. Small explosions were recorded during 27-28 October. A satellite image from 28 October showed a 850-m-long SWIR anomaly on the NW flank from a lava flow. A central spatter cone was visible. Spatter deposits on the snow at the upper flanks was evident, and tephra deposits extended about 2.5 km N. The lahar on the NW flank branched extensively at lower elevations and was at least 5 km long. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

JMA reported that two eruptive events at Minamidake crater (at Aira Caldera’s Sakurajima volcano) recorded during 25-28 October generated plumes that rose 1.2 km. The Alert Level remained at 3 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 23-29 October ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 18, 20-21, and 23 October that sent ash plumes up to 3 km (10,000 ft) a.s.l. Ash plumes drifted N, E, and SE. A weak thermal anomaly was identified in satellite images on 20 October. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

On 25 October PHIVOLCS lowered the Alert Level for Kanlaon to 0 (on a scale of 0-5) noting that volcanic activity had declined to baseline levels in June and had continued to be low.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

PVMBG reported that during 21-27 October lava continued to effuse from Karangetang’s Main Crater (S), traveling as far as 1.8 km down the Nanitu, Pangi, and Sense drainages on the SW and W flanks. Incandescence from both summit craters was visible at night. Sometimes dense white plumes rose to 500 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

PVMBG reported that during 21-27 October diffuse white plumes rose as high as 100 m above Anak Krakatau’s active vent. As many as three eruptive events per day during 25-27 October generated ash plumes that rose as high as 200 m above the vent. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km-radius hazard zone from the crater.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

ONEMI and SERNAGEOMIN reported that during 22-24 October white-to-gray plumes from Nevados de Chillán’s Nicanor Crater rose as high as 1.3 km above the rim and drifted SE. Explosions ejecting incandescent material onto the flank were visible at night. A new lava flow from the crater had begun to effuse on 16 October and continued to very slowly advance on the NE flank. Diffuse white plumes rose from the crater on 25 and 29 October; cloudy weather obscured views in between those dates. The volcano Alert Level remained at Orange, the second highest level on a four-color scale. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for the communities of Pinto, Coihueco, and San Fabián, and stated that the public should stay at least 3 km away from the crater on the SW flank and 5 km away on the ENE flank.

Sources: Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), Servicio Nacional de Geología y Minería (SERNAGEOMIN)

OVPF reported that inflation began to be detected at Piton de la Fournaise on 11 October and a seismic crisis was recorded on 21 October. A second seismic crisis began at 0415 on 25 October accompanied by rapid deformation. Volcanic tremor began at 1440, signaling the arrival of magma to the surface; the eruption area was not visible in webcam views. Field observers first saw two active fissures at the S part of l’Enclos Fouqué at an elevation of 1,400 m. Several lava flows were identified, with the front of the longest flow reaching an area 2 km upstream from National Road RN2 by 1700. Tremor intensity began to decline around three hours after the start of the eruption and continued to decline through the morning of 26 October. That same morning there was one active vent producing 10-20-m-high lava fountains. Downstream of piton Tremblet the flow forked and by 1700 on 26 October the leading toe was about 250 m from RN2. On 27 October tremor intensity fluctuated concurrently with the variable intensity of cone formation. The cone had grown to 10 m high and lava was ejected 20 m above the cone rim. Only one lava flow was active and was 200 m long; the flow near RN2 had not progressed. The eruption ceased at 1630.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

Instituto Geofísico del Perú (IGP) reported that an average of 48 low-to-medium intensity explosions per day occurred at Sabancaya during 21-27 October. Gas-and-ash plumes rose as high as 2.5 km above the summit and drifted W, SW, and S. There were 15 thermal anomalies identified in satellite data. The report noted that the lava dome in the summit crater had been slowing extruding since February and filling in the N part of the crater, though the rate of the extrusion had increased in recent months. On 26 October Observatorio Vulcanológico del INGEMMET (OVI) conducted a drone overflight and captured video of the lava dome. The estimated volume of the lava dome was 4.6 million cubic meters based on the footage. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12-km radius.

Sources: Instituto Geofísico del Perú (IGP), Andina Agencia Peruana de Noticias

The Darwin VAAC reported that during 26-28 October multiple discrete ash emissions from Sangeang Api rose to 2.1-2.7 km (7,000-9,000 ft) a.s.l. and dissipated rapidly to the NW, WNW, and W. A thermal anomaly was visible in satellite images on 26 October. The Alert Level remained at 2 (on a scale of 1-4).

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 18-25 October. Resuspended ash drifted 110 km SE during 19-20 October. Explosions recorded on 21 October generated ash plume that rose to 10-11 km (32,800-36,100 ft) a.s.l. and drifted 1,300 km SE. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

GeoNet reported that sulfur dioxide emissions and the level of volcanic tremor both increased at White Island over the past several months, and were at the highest levels since 2016. The report noted that the changes could be related to a variety of processes, including an increased level of unrest, though the level of hazards on the island remained unchanged; the Volcanic Alert Level remained at 1 (the second lowest level on a 0-5 scale) and the Aviation Color Code remained at Green. The crater lake level continued to rise and impact surface activity around vents, creating small-scale geysering, on the W side of the crater floor.

Source: GeoNet