Report for Piton de la Fournaise
OVPF reported that a seismic crisis at Piton de la Fournaise began at 0623 on 19 September. Volcanic tremor located beneath the SSW part of the caldera began at 0748, likely signifying the arrival of magma at the surface, though weather clouds prevented visual confirmation from webcams. Pelotons de Gendarmerie de Haute Montagne (PGHM) teams that were on-site to evacuate people from inside the caldera observed lava fountains 20-30 m high rising from a fissure that had opened E of Piton Kala Pélé. The eruption was confined to the caldera, so the Alert Level was raised to 2-1 (“2” is the highest level of a 3-level scale and “-1” denotes the lowest of three sub-levels). By 20 September lava fountaining had decreased and the focus of the eruption was at the lower part of the fissure. Sulfur dioxide emissions peaked at an estimated 8,000 tons per day at the beginning of the eruption and then decreased to about 2,300 tons per day during 20-21 September.

Report for Whakaari/White Island
GeoNet reported that minor ash emissions from the active vent area in Whakaari/White Island’s crater were visible in webcam images on 18 September. The Aviation Color Code was raised to Orange; the Volcanic Alert Level remained at 2. Minor light brown ash emissions were visible through the day, and rose no higher than 600 m above the volcano. Ash emissions were not visible beyond the island, but a steam plume was seen from the Bay of Plenty coast. A strong sulfur dioxide signal associated with the emissions was identified in satellite images that same day. One of the seismic stations began working again on 19 September and showed typical low-level seismicity, consistent with no visible ash emissions. GeoNet was unable to accurately characterize the ash emissions due to the lack of data from inoperable instruments and the semi-operational webcam on the island. They noted that the most likely cause was a small amount of magma moving into the shallow part of the volcano.

Report for Taupo
On 20 September GeoNet raised the Volcanic Alert Level for Taupo to 1 (the second lowest level on a six-level scale) reflecting “minor volcanic unrest” characterized by ongoing seismicity and inflation. Seismicity beneath Lake Taupo began increasing in May. Earthquakes occurred at a rate of about 30 per week but increased to about 40 per week in early September. A M 4.2 earthquake, the largest so far this year, was recorded on 10 September and felt by over 1,000 people. By 20 September over 700 earthquakes had been located with depths less than 30 km, though most ranged 4-13 km. The earthquake locations were in two clusters: a larger cluster beneath the central and E part of the lake, and a smaller cluster to the W centered just offshore from Karangahape. 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 area of uplift corresponded to the main seismic swarm. 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. There have been 17 previous episodes of unrest at Taupo over the previous 150 years, some more notable than the current episode, and many others before written records. None resulted in an eruption, with the last eruption occurring around 232 CE. The Volcanic Alert Level change was informed by ongoing analysis of monitoring data, research, and deepening knowledge of past unrest.

Report for Home Reef
The Tonga Geological Services reported that the new island at Home Reef that emerged from the ocean on 10 September continued to grow through 20 September. The eruption continued at variable intensities, producing daily plumes of gas and steam that rose no higher than 1 km above sea level. The island was surrounded by plumes of discolored water. The island was 170 m in diameter by 16 September and had grown to 182 m N-S and 173 m E-W by 18 September. Steam plumes with some ash content rose 3 km during 19-20 September. Mariners were advised to stay 4 km away from the volcano.

Report for Kadovar
Based on satellite and wind model data, the Darwin VAAC reported that on 18 September multiple, discrete, ash plumes from Kadovar rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW and WNW.

Report for Merapi
BPPTKG reported that the eruption at Merapi continued during 9-15 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 1.8 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.

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 13-20 September. Eruptive events at 0524 on 17 September and 0505 on 19 September produced ash plumes that rose 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.

Report for Lewotolok
PVMBG reported that the eruption at Lewotolok continued during 13-20 September. Daily white emissions rose as high as 300 m above the summit and drifted in multiple directions. During 16-19 September white-and-gray or white, gray, and black plumes rose as high 1 km and drifted W and NW. Incandescence above the crater rim was visible in some webcam photographs posted during 14-15 September. 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.

Report for Ibu
PVMBG reported that the eruption at Ibu continued during 14-20 September. Gray-and-white ash plumes of variable densities rose as high as 800 m above the summit and drifted in multiple directions. The Alert Level remained at a 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 Suwanosejima
JMA reported that the eruption at Suwanosejima's Ontake Crater continued during 12-19 September. A total of 11 explosions produced eruption plumes that rose as high as 1.4 km above the crater rim and ejected large blocks 600 m from the vent. Volcanic tremor was occasionally recorded. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Report for Aira
JMA reported that 10 explosions at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) were recorded during 12-19 September. Volcanic plumes produced by the explosions rose as high as 1.6 km above the crater rim and ballistics were ejected as far as 1.3 km from the vent. Sulfur dioxide emissions were high at 2,400 tons per day on 24 September. Nighttime incandescence at the crater was visible during 2-16 September. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Report for Ebeko
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 3.6 km (11,800 ft) a.s.l. and drifted in multiple directions. A thermal anomaly over the volcano was identified in satellite images during 8 and 12-13 September. Ash fell in Severo-Kurilsk during 9-10 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.

Report for Alaid
KVERT reported that an intense thermal anomaly over Alaid identified in satellite images beginning at 1139 on 15 September (local time) likely indicated the onset of a Strombolian eruption. The Aviation Color Code was raised to Yellow (the second lowest level on a four-color scale) the next day. Satellite images acquired at 1108 on 18 September showed a gas-and-steam plume containing ash drifting ESE. Several photographs of the eruption were taken that same day. The Aviation Color Code was raised to Orange.

Report for Karymsky
KVERT reported that a weak thermal anomaly over Karymsky was identified in satellite images during 9 and 10-11 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.

Report for Sheveluch
KVERT reported that the ongoing eruption at Sheveluch was characterized by explosions, hot avalanches, and lava-dome extrusion during 8-15 September. A daily thermal anomaly was identified in satellite images. Plumes of re-suspended ash drifted 90 km E on 8 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.

Report for Semisopochnoi
AVO reported that the eruption at Semisopochnoi was ongoing during 13-20 September. Seismicity remained elevated and characterized by intermittent tremor. Low-level ash emissions from the N crater of Mount Cerberus were occasionally visible in mostly cloudy webcam views during 13-15 September. Possible fresh local ashfall was seen in webcam images during 16-17 September. Steam emissions were visible in webcam views during 19-20 September. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Report for Great Sitkin
AVO reported that slow lava effusion at Great Sitkin likely continued during 13-20 September, an analysis confirmed by clear satellite images during 13-15 September. Lava flowed outward from the vent area but flows at the margins did not advance. Minor steam emissions were also visible during 13-14 September and elevated surface temperatures were identified during 13-15 and 17-18 September. Weather cloud cover occasionally prevented webcam and satellite views. A data outage affected the local seismic network during 16-20 September, though no significant activity was detected on regional geophysical networks. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Pavlof
AVO reported that a minor eruption at a vent on Pavlof’s upper E flank was ongoing during 13-20 September. Seismic tremor persisted. New lahar and minor ash deposits extending less than 900 m from the vent were visible during 11-13 September. Strong incandescence at the vent and from an area within 200 m downslope was visible in webcam images starting on 14 September, signifying the emplacement of a short lava flow. Elevated surface temperatures over the vent and flow were identified in satellite images through 20 September; lava effusion continued but no active lava flows extended down the flank from the vent. Explosions were recorded during 18-19 September and steam emissions were visible in webcam images during 19-20 September. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Report for Kilauea
HVO reported that lava continued to effuse from a vent in the lower W wall of Kilauea’s Halema`uma`u Crater during 13-20 September, entering the lava lake and flowing onto the crater floor. Part of the lake’s surface was continuously active. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Rincon de la Vieja
OVSICORI-UNA reported continuing eruptive activity at Rincón de la Vieja characterized by occasional small phreatic explosions. A small explosion at 0147 on 14 September produced a steam-and-gas plume that rose 600 m above the crater rim. Low-frequency tremor began at 0900 on 17 September and was possibly associated with small eruptive events, though they were not visually confirmed. A possible emission was recorded at 0219.

Report for Purace
Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico Colombiano (SGC), reported that during 13-19 September the number of earthquakes at Puracé was slightly higher compared to previous weeks. A seismic swarm was recorded on 15 September. Events were located about 1.5 km SW of Puracé crater, at depths of 3-4 km, and were as large as M 1.3. A total of 904 earthquakes were recorded during the week; 296 of those were volcano-tectonic events, 538 were long-period events, 54 were low-energy pulses of tremor, 11 were tornillo-type events, and five were hybrid events. Data from the GNSS (Global Navigation Satellite System) geodetic network indicated continuing inflation. White gas plumes were visible in the Anambío, Mina, Lavas Rojas, Cerro Sombrero, and Curiquinga webcams drifting NW. Sulfur dioxide emissions were as high as 2,021 tonnes per day. The Alert Level remained at Yellow (the second lowest on a four-color scale).

Report for Nevados de Chillan
SERNAGEOMIN reported that a long-period earthquake signals were recorded at Nevados de Chillán at 0750 and 1913 on 19 September. Associated emissions at 0750 rose 1.1 km above the summit and drifted NE, and at 1913 rose 1.7 km above the summit and drifted SE. The Alert Level remained at Yellow, the second lowest 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, 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.

Report for Krysuvik-Trolladyngja
IMO stated that the Fagradalsfjall and Krýsuvík-Trölladyngja volcanic systems have been designated as two separate systems based on previous scientific research combined with data collected and analyzed from the two recent eruptions (2021 and 2022). On 15 September the Aviation Color Code for Krýsuvík-Trölladyngja was changed to Green, reflecting that the activity was at known background levels.

Report for Fagradalsfjall
IMO stated that the Fagradalsfjall and Krýsuvík-Trölladyngja volcanic systems have been designated as two separate systems based on previous scientific research combined with data collected and analyzed from the two recent eruptions (2021 and 2022). On 15 September the Aviation Color Code for Fagradalsfjall was lowered to Green; lava from the fissure that opened in Meradalir stopped erupting on 21 August. Seismicity remained at low levels and no deformation was detected.