KVERT reported that a thermal anomaly over Alaid was identified in satellite images during 15-22 September. On 18 September an ash plume drifted 50 km E. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The Tonga Geological Services reported that the new island at Home Reef that emerged from the ocean on 10 September continued to grow through 27 September. The eruption continued at variable intensities, mainly producing daily plumes of gas and steam that rose no higher than 2 km above sea level. During 0040-0250 on 25 September steam-and-ash plumes rose 2-4 km a.s.l. and drifted 30 km W, S, and SE. At 0030 on 27 September an ash plume rose 6-8 km a.s.l. and drifted 25 km SSE. The island was surrounded by plumes of discolored water. Mariners were advised to stay 4 km away from the volcano.

Source: Tonga Geological Services, Government of Tonga

OVPF reported that the eruption at Piton de la Fournaise that began on 19 September, E of Piton Kala Pélé, was ongoing during 21-27 September. Gas plumes drifted SW, WSW, W, NNW, and were detected as far as 200 km from the vent in a 27 September satellite image. The active cone on the low end of the fissure ejected lava to low heights above the cone’s rim. Lava flows from the base of the cone formed two main flows that traveled SE and ESE. Lava flowed through sections of tubes mainly located along the first kilometer of both flows. Average daily lava-flow rate estimates varied from 1 to 8 meters per second based on satellite data. The SE flow front had advanced to the Château Fort crater area, reaching 2,000 m elevation on 24 September, though that flow had stopped advancing by 26 September. The eruption was confined to the caldera, so the Alert Level remained at 2-1 (“2” is the highest level of a 3-level scale and “-1” denotes the lowest of three sub-levels).

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

On 28 September GeoNet reported that seismic unrest and deformation at Taupo continued during the previous week. About 750 earthquakes have been located at depths of 4-13 km beneath the lake since unrest began in May. During the past week the locations were concentrated beneath the E part of the lake and occurred at a slightly lower rate than the week before. An area of deformation at Horomatangi Reef had been rising at a rate of 60 mm (plus or minus 20 mm) per year since May. The data suggested that the seismicity and deformation was caused by the movement of magma and hydrothermal fluids. GeoNet noted that unrest at calderas was common and may continue for months or years without resulting in an eruption; more significant unrest would be indicated by additional indicators of activity and substantial impacts on the local area. The Volcanic Alert Level remained at 1 (the second lowest level on a six-level scale) reflecting “minor volcanic unrest” characterized by ongoing seismicity and inflation.

Source: GeoNet

JMA reported that six eruptive events and three explosions at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) were recorded during 19-26 September. Volcanic plumes rose as high as 2.4 km above the crater rim and large blocks were ejected as far as 700 m from the vent. Incandescence at the crater was visible nightly. Sulfur dioxide emissions were somewhat high at 1,900 tons per day on 22 September. Nighttime incandescence at the crater was visible during 2-16 September. A notable eruptive event at 1335 on 23 September generated an ash plume that rose 1.7 km above the crater rim and also drifted down-flank to the SE until 1600. A large amount of ashfall was deposited on the SE flank. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

KVERT reported that moderate activity at Ebeko was ongoing. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions generated ash plumes that rose up to 3.5 km (11,500 ft) a.s.l. and drifted E. A thermal anomaly over the volcano was identified in satellite images on 18 September. Ash fell in Severo-Kurilsk during 20-22 September. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

AVO reported that slow lava effusion at Great Sitkin likely continued during 20-27 September. Elevated surface temperatures were identified during 20-21 September; weather clouds often prevented webcam and satellite views during the rest of the week. A data outage that affected the local seismic network was resolved by 23 September. Seismicity was low during 24-25 September. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

KVERT reported that a weak thermal anomaly over Karymsky was identified in satellite images during 16-18 and 20-21 September. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

HVO reported that lava continued to effuse from a vent in the lower W wall of Kīlauea's Halemaʻumaʻu Crater during 20-27 September, entering the lava lake and flowing onto the crater floor. The continuously active part of the lake dropped 10 m, regained 3 m during 19-22 September, and then was unchanged the rest of the week. Breakouts of lava occurred at the W and N margins of the lake during most of the week. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Strong winds re-suspended ash from the E flank of Klyuchevskoy and created plumes that were visible in satellite images drifting 460 km SE during 21-22 September. KVERT raised the Aviation Color Code to Orange on 21 September but lowered it back to Green on 24 September. Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

PVMBG reported that the eruption at Lewotolok continued during 20-27 September. Daily white emissions rose as high as 350 m above the summit and drifted in multiple directions. At 0350 on 23 September an eruptive event produced an ash plume that rose 800 m and drifted W. An image captured at that time showed Strombolian activity with incandescent material being ejected above the summit. White-and-gray plumes generally rose as high 500 m and drifted NW, W, and S that same day. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater and 4 km away from the crater on the SE flank.

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

BPPTKG reported that the eruption at Merapi continued during 16-22 September and seismicity remained at high levels. As many as 13 lava avalanches from the SW lava dome traveled down the Bebeng drainage on the SW flank, reaching a maximum distance of 1.9 km. No morphological changes to the SW and central lava domes were evident in photographs. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

AVO reported that a minor eruption at a vent on Pavlof’s upper E flank was ongoing during 20-27 September. Small explosions were detected in seismic and infrasound data during 20-21 September; seismic tremor levels were variable during the rest of the week. Weather clouds often prevented views of the volcano, though elevated surface temperatures were identified in satellite and webcam images during 20-21 and 23-27 September. A diffuse gas was occasionally seen in webcam images during 25-26 September, and one plume with possible ash content was visible during 26-27 September. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

On 25 September PHIVOLCS warned of potential lahars around Pinatubo due to intense rains from a typhoon expected during 25-26 September. Significant deposits from 1991 pyroclastic density currents on the W flank may be remobilized, generating lahars down major drainages in that watershed. PHIVOLCS noted that the communities of San Marcelino, San Narciso, San Felipe, and Botolan, Zambales Province, and communities in Tarlac and Pampanga Provinces may be affected by lahars and flooding.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

IG characterized the ongoing eruption at Reventador as moderate during 20-27 September. Gas, steam, and ash plumes, observed with webcams or reported by the Washington VAAC, rose as high as 1.3 km above the summit and drifted SW, W, NW, and NE. Crater incandescence was visible nightly; the lava flow on the NE flank continued to be active, and incandescent blocks were visible rolling 600-800 m down the flanks during 20-23 and 26-27 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

IG reported a high level of activity at Sangay during 20-27 September. Daily seismic counts ranges were 702-1,152 explosions, 12-105 long-period events, and 9-95 tremor events indicating emissions. Daily ash-and-gas plumes were identified in IG webcam images and visible in satellite images according to the Washington VAAC. Plumes generally rose as high as 2 km above the volcano but during 25-27 September they rose as high as 3 km. The plumes drifted mostly W and NW, but some drifted SW, N, and NE. Daily thermal anomalies were identified in satellite images. Ashfall was reported in the Chauzán sector, Chimborazo province, during 22-23 September.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

PVMBG reported that the eruption at Semeru continued during 20-27 September. Eruptive events on 24 September (at 0606) and 27 September (at 0517 and 0651) produced ash plumes that rose 400-500 m above the summit and drifted W and SW. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 5 km away from the summit, and 500 m from Kobokan drainages within 17 km of the summit, along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

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

AVO reported that the eruption at Semisopochnoi was ongoing during 13-20 September. Seismicity remained elevated with intermittent periods of low-amplitude tremor. Steam emissions from the active vent in the N crater of Mount Cerebus were visible in webcam views on most days. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

KVERT reported that the ongoing eruption at Sheveluch was characterized by explosions, hot avalanches, and lava-dome extrusion during 15-22 September. A daily thermal anomaly was identified in satellite images. Plumes of re-suspended ash drifted 430 km E during 17-18 and 21-22 September. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 19-26 September. A total of 19 explosions produced eruption plumes that rose as high as 2 km above the crater rim. Crater incandescence was visible nightly and ash fell in Toshima village (3.5 km SSW). The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Source: Japan Meteorological Agency (JMA)

On 25 September PHIVOLCS warned of potential lahars around Taal due to intense rains from a typhoon expected during 25-26 September, with a particular focus on the western part of the caldera where ash deposits could become remobilized and affect the communities of Agoncillo and Laurel, Batangas Province. The report also warned that the ground cracks formed during the 2020 eruption on the NE and SW sectors of Taal Caldera may become enlarged or eroded and cause damage to buildings and houses. The ground cracks were located in the municipalities of Agoncillo, San Nicolas, Lemery, and Taal on the SW part of the caldera, and in the cities of Talisay and Tanauan on the NE side.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)