The Darwin VAAC reported that continuous ash plumes from Bagana were identified in satellite images rising to 2.4-3.7 km (8,000-12,000 ft) a.s.l. and drifting S and SW at 2310 on 16 September and 0150 and 0410 on 17 September.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

PHIVOLCS reported continuing unrest at Kanlaon during 11-17 September, characterized by increased seismicity and sulfur dioxide emissions. Sulfur dioxide emissions reached a record high on 11 September, averaging 11,556 tonnes/day (t/d), before decreasing slightly to 10,880 t/d on 12 September; emissions were not reported the rest of the week. The number of volcanic earthquakes detected by the seismic network was 337 during 10-11 September and 79 recorded during 11-12 September. The daily number fluctuated from 2 to 32 on the other days. Weather clouds obscured views of the summit during the second half of the week. The Alert Level remained at 2 (on a scale of 0-5) and PHIVOLCS reminded the public to remain outside of the 4-km-radius Permanent Danger Zone and warned pilots not to fly close to the volcano. According to a Disaster Response Operations Monitoring and Information Center (DROMIC) report there were a total of 2,298 people in evacuation centers as of 16 September.

Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Disaster Response Operations Monitoring and Information Center (DROMIC)

HVO reported that deformation analysis of an interferogram based on satellite images acquired over Kīlauea during 2-14 September indicated that a dike intruded between Pauahi and Makaopuhi craters along the middle East Rift Zone. Seismicity and deformation increased dramatically at around 1600 on 14 September with most of the earthquakes located at depths of 1-3 km below the surface. The largest earthquake was an M 4.3 recorded at 1625 on 14 September and located in the S part of Kaluapele; this earthquake was associated with slip along one of the outer caldera faults and a consequence of stress changes due to the dike intrusion. Activity levels decreased overnight during 14-15 September; seismicity continued at less intense levels on 15 September, though deformation data continued to show moving magma.

During 2100-2200 on 15 September, infrasound instruments detected strong signals typical of gas or steam venting, and seismometers in the middle East Rift Zone recorded weak, sustained, low-frequency tremor. Residents in nearby subdivisions downwind reported smelling volcanic gas around that same time. There was no evidence of eruptive activity in webcam images and GOES satellite data did not show thermal anomalies, though heavy rainfall in the area complicated the interpretation. HVO issued a Volcanic Activity Notice (VAN) at 0023 on 16 September raising the Volcano Alert Level to Watch (the third level on a four-level scale) and the Aviation Color Code to Orange (the third color on a four-color scale) and noting that monitoring data indicated a continuing intrusion. Hawaiʻi Volcanoes National Park closed the Chain of Craters Road and other nearby areas in response to the increased activity.

During an overflight around 1000 on 16 September HVO scientists confirmed that an eruption had occurred during the night in an area just W of Napau Crater, near the Napau campsite in a remote area of the National Park. Two lava flows had erupted from a 480-m-long fissure with two segments, covering an area of approximately 16,500 square meters; the larger flow was about 200 m long. No active lava flows were seen during the overflight, but gas-and-steam was rising from the fissure. The campground was not affected but lava possibly covered a pulu (Hawaiian tree fern) station nearby, and vegetation along the margins of the flow field was burned. Chain of Craters Road is downslope and downwind of the new fissures.

The eruption resumed at about 1800 on 16 September with the activity visible in webcam images. During an overflight during the morning of 17 September volcanologists observed activity at fissures that had opened on the Napau Crater floor, downrift (NE) of the previous fissures that had opened on 15 September and were no longer active. The fissure on the crater floor was about 500 m long and trended E-W along the N part of the crater floor. Lava fountains rose 10 m from areas along the fissure, and by 0830 about 25-30 percent of the crater floor had been covered by lava. HVO released a map showing the margins the flow field as of 1030 on the 17th, based on observations made during the last helicopter overflight. The map showed that lava from the first set of fissures had flowed NE down into the Napau Crater during 16-17 September. The total length of the fissure system was more than 1.6 km and lava flow covered about 18 hectares (180,000 square meters).

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO), US Hawaii Volcanoes National Park

GeoNet reported that a low-level eruption at Whakaari/White Island was ongoing through 12 September, confirmed by data from webcams, overflights, and satellite images. Sulfur dioxide emissions recorded during a 5 September overflight were some of the highest during the previous 20 years. The rate of emissions was lower during an 11 September overflight; though emissions were variable the total gas output remained at higher than normal levels. The vent area appeared slightly larger on 11 September.

The plumes were darker and higher based on webcam images on 11 September, suggesting a substantially higher ash content; less ash was present in the plumes on 12 September. According to the Wellington VAAC ash-and-gas plumes rose 0.9 km (3,000 ft) a.s.l. and drifted E and SE during 13-14 September. The gas-and-ash plumes had been rising a few hundred meters to 1 km above the volcano and drifting tens of kilometers downwind. The plumes were sometimes tracked as far as 100 km downwind, and occasionally the plumes had passed over land. Ash fell as far as 3 km from the island. The Volcanic Alert Level remained at 3 (on a scale of 0-5) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Sources: GeoNet, Wellington Volcanic Ash Advisory Center (VAAC)

JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 9-16 September. Crater incandescence was visible in webcam images during dark hours, and there were occasional very small eruptive events. An explosion at 1332 on 16 September generated an ash plume that rose 1.5 km above the crater rim and drifted NW. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 1 km away from both craters.

Source: Japan Meteorological Agency (JMA)

PVMBG reported that the eruption at Dukono was ongoing during 11-17 September. Gray-and-white ash plumes that were sometimes dense rose 100-600 m above the summit and drifted E on 11 and 17 September. Emissions were not observed on the other days. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

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

KVERT reported that moderate explosive activity was ongoing at Ebeko during 6-12 September. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 5-9 and 11-12 September generated ash plumes that rose as high as 3 km (10,000 ft) a.s.l. and drifted N, NE, and E. Satellite data indicated that either no activity was observed, or weather conditions prevented views. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

AVO reported that slow lava effusion continued to feed a thick lava flow in Great Sitkin’s summit crater during 10-17 September. Seismicity was low with few small daily earthquakes and rockfalls associated with the advancing E lobe. Elevated surface temperatures over the active flow were identified in satellite data on 11 September. Weather clouds often obscured views of the summit. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

PVMBG reported that activity at Ibu continued during 11-17 September with multiple eruptive events recorded daily. On most days gray or white-and-gray ash plumes that were sometimes dense rose as high as 1.5 km above the summit and drifted in multiple directions. Two eruptive events were recorded on 14 September, though no emissions were visible. Some webcam images posted with the reports showed incandescence visible above the crater rim. The Alert Level remained at 3 (the second highest level on a four-level scale) and the public was advised to stay 4 km away from the active crater and 5 km away from the N crater wall opening.

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

KVERT reported moderate levels of activity at Karymsky during 6-12 September. Explosions during the week produced ash plumes that rose as high as 3 km (10,000 ft) a.s.l. and drifted 500 km NE. A thermal anomaly over the volcano was identified in satellite images during 7-8 September. The Aviation Color Code remained at Orange (the third 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)

PVMBG reported that eruptive activity at Lewotobi’s Laki-laki volcano continued during 11-17 September from a vent on the upper NW flank. Daily gray or white-and-gray ash plumes that were sometimes dense rose as high as 1 km above the summit and drifted SW, W, and NW. The Alert Level remained at 3 (the second highest level on a scale of 1-4) and the public was warned to stay outside of the exclusion zone, defined as a 3 km radius around both Laki-laki and Perempuan craters, 4 km to the NNW and SSE of Laki-laki.

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

The Darwin VAAC reported that at 2040 on 11 September an ash plume from Manam was identified in a satellite image rising 5.2 km (17,000 ft) a.s.l. and drifting NNW. The plume had dissipated by 0210 on 12 September.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 11-17 September. On 11 and 13 September white emissions rose 100-150 m above the summit and drifted E. White-and-gray ash plumes rose 100-300 m above the summit and drifted E and NE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 3 km away from the active crater.

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

BPPTKG reported that the eruption at Merapi (on Java) continued during 6-12 September. Seismicity was slightly more intense compared to the previous week. The SW lava dome produced 167 lava avalanches that traveled as far as 1.8 km down the Bebeng drainage on the SW flank. Three pyroclastic flows descended the Bebeng as far as 1.5 km. Morphological changes to the SW lava dome were due to continuing effusion and collapses of material. 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)

Satellite images from 13 and 18 September indicated continuing activity at Nyamuragira. The end of the NNW lava flow was about 7.6 km from the crater rim based on a 13 September satellite image and had advanced a short distance by 18 September. Lava had branched from the flow in an area about 1.3 km upslope from the end of the flow and traveled about 1.6 km NE. Lava flows that had breached the NNW crater rim traveled W and SW. The farthest end of the W flow was about 5 km from the crater rim and the end of the SW flow was about 3 km from the crater rim. Small thermal anomalies were visible near the ends of the NNW flow and in areas along the W and WSW flows. A larger thermal anomaly was present the part of the eastern crater floor. An 18 September image showed that the thermal anomaly in the main crater had shifted to the NW part of the crater. Scattered thermal anomalies on the flow fields indicated breakouts in areas along the margins of the NNW, W, and SW. Weather clouds slightly obscured the crater and flow field in the 13 September image but obscured most of the flow field and part of the crater in the 18 September image.

Source: Copernicus

CENAPRED reported that eruptive activity continued at Popocatépetl during 10-17 September. The seismic network recorded 18-65 long-period events per day that were accompanied by steam-and-gas emissions which sometimes contained minor amounts of ash. The seismic network also recorded daily tremor with periods lasting from 46 minutes up to six hours and 37 minutes. Two volcano-tectonic earthquakes were recorded during 12-14 September. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

Instituto Geofísico del Perú (IGP) reported that the eruption at Sabancaya continued during 9-15 September with a daily average of 34 explosions. Gas-and-ash plumes rose as high as 2 km above the summit and drifted less than 10 km SE and S. Thermal anomalies over the lava dome in the summit crater were identified in satellite data. Slight inflation was detected N of Hualca Hualca (7 km N). Sulfur dioxide emissions were at moderate levels, averaging 580 tons per day. The Alert Level remained at Orange (the third level on a four-color scale) and the public was warned to stay outside of a 12 km radius.

Source: Instituto Geofísico del Perú (IGP)

PVMBG reported that eruptive activity continued at Semeru during 11-18 September with multiple daily eruptive events recorded by the seismic network. White-and-gray ash plumes that were sometimes dense rose 150-700 m above the summit and drifted in multiple directions. The Alert Level remained at 2 (the second lowest level on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km from the summit, and to avoid other drainages 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)

KVERT reported that during 6-12 September lava extrusion likely continued at Sheveluch’s “300 years of RAS” dome on the SW flank of Old Sheveluch and at Young Sheveluch. Thermal anomalies over the domes were identified in satellite images on 7 and 10 September; weather clouds obscured the volcano on the other days. 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 eruptive activity at Suwanosejima's Ontake Crater continued during 9-16 September and crater incandescence was observed nightly in webcam images. Explosions were recorded at 1728 on 9 September, at 1001 on 11 September, at 1345 on 12 September, and at 1948 on 13 September. Volcanic plumes generated by the explosions rose as high as 800 m above the crater rim. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1.5 km away from the crater.

Source: Japan Meteorological Agency (JMA)