Report for Nyamulagira
The eruption at Nyamulagira continued in December based on observations using satellite images. Incandescence on the floor of the summit caldera and from active lava flows on the NW flanks was visible in a 7 December satellite image. The distal end of the farthest lava flow was about 6.5 km from the crater rim.

Report for Piton de la Fournaise
The Observatoire Volcanologique du Piton de la Fournaise (OVPF) reported that a magmatic intrusion was detected beneath the E rim of Dolomieu Crater at Piton de la Fournaise during 2225-2330 on 5 December based on seismic data. The seismic network recorded 227 shallow volcano-tectonic earthquakes with magnitudes less than 1 at depths of 1.8-2.3 km. Some of the located earthquakes showed that magma migrated less than 500 m from an area below the SE rim to an area below the NE rim. The seismicity was accompanied by rapid, low-magnitude deformations at the summit area that lasted less than an hour. Seismicity continued after the intrusion ceased, with a decreasing rate through the next day. The Alert Level was raised to 1 (or an Orange Alert). During 7-8 December seismicity had returned to a rate of 1-3 earthquakes per hour, comparable to before the intrusion. The Alert Level was lowered back to "Vigilance" (or a Yellow Alert) was initiated on 28 November and described as “a possible eruption in medium term (a few days or weeks) or presence of risks on the sector (rockfalls, increase of gas emissions, still hot lava flows)”.

Report for Whakaari/White Island
On 8 December GeoNet reported that eruptive activity at Whakaari/White Island had declined and that no ash emissions had been detected during the previous week. Sources of recent observations included an overflight, ongoing satellite monitoring, and images from the Whakatane and Te Kaha webcams along the Bay of Plenty coast. Gas sampling during the overflight revealed lower levels of sulfur dioxide than previous measurements. The Volcanic Alert Level was lowered to 2 (on a scale of 0-5) and the Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale).

Report for Manam
The Darwin Volcanic Ash Advisory Centre (VAAC) reported that ash plumes from Manam were identified in satellite images and reported by the Rabaul Volcano Observatory drifting SE and SW at an altitude of 2.4 km (8,000 ft) a.s.l. during 5-6 December.

Report for Ambae
The Vanuatu Meteorology and Geohazards Department (VMGD) reported eruptive activity at Ambae during the last week of November and the first week of December based on seismic signals, satellite data, and webcam images. Steam, gas, and ash plumes were visible in satellite and webcam observations during 24-30 November and 1-5 December. A low-level thermal anomaly was also detected in satellite images during 30 November and 1-2 December. Ashfall was reported in surrounding communities downwind in late November and during 1-7 December. A webcam image from 8 December showed a plume that may have contained ash rising from the crater. According to the Wellington Volcanic Ash Advisory Center (VAAC) low-level ash plumes rose 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NW during 3-5 December, then rose as high as 3.7 km (12,000 ft) a.s.l. and drifted E during 7-8 December. The Alert Level remained at 2 (on a scale of 0-5), and the public was warned to stay outside of Danger Zone A, defined as a 2-km radius around the active vents in Lake Voui, and to stay away from drainages during heavy rains.

Report for Bur ni Telong
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increased seismicity at Bur ni Telong. The seismic network detected an increase in the number of deep volcanic events, with 87 events recorded during 1-3 December. Additionally, the network recorded 19 local tectonic earthquakes. During 0000-1317 on 4 December there were 39 shallow volcanic earthquakes, one deep volcanic earthquake, and two local tectonic earthquakes. No emissions were observed. The Alert Level remained at 2 (the second lowest level on a scale of 1-4), though at 1500 on 4 December the exclusion zone was increased to a radius of 3 km from the crater area. The public was reminded to avoid the fumarole and solfatara regions, especially during cloudy or rainy weather.

Report for Marapi
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruptive event at Marapi (on Sumatra) was recorded at 1616 on 4 December. Emissions were not observed due to weather clouds. 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.

Report for Semeru
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru during 3-9 December, with daily eruptive events recorded by the seismic network. Daily white-and-gray or gray ash plumes rose 400-1,100 m above the summit and drifted in multiple directions. Incandescence at the summit on the upper SE flank was visible in several nighttime webcam images. The Alert Level remained at 3 (the second lowest level on a scale of 1-4) and the public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit on the SE flank along the Kobokan drainage, and 500 m from the banks of the Kobokan drainage as far as 17 km SE of the summit.

Report for Lewotobi
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity at Lewotobi Laki-laki had significantly declined during the previous few weeks. Seismic data showed decreased activity; specifically, signals indicated fluid movement at depth and not magma migration towards the surface. There was also a lack of shallow volcanic earthquakes indicating no significant pressures higher in the conduit. The intensity of surficial activity decreased during 1-7 December, with fluctuating avalanche earthquake signals due to instability of material on the flanks. Deformation data showed a decreasing trend during October-December. On 8 December the Alert Level was lowered to 3 (the second highest level on a scale of 1-4) and the public was warned to stay 6 km away from the center of Laki-laki.

Report for Ibu
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 3-8 December. Daily white-to-gray or gray ash plumes rose 200-600 m above the summit and drifted NE, E, and SE; weather conditions occasionally prevented visual confirmation. Incandescence at the summit was visible in a few nighttime webcam images. The Alert Level remained at 2 (the second lowest level on a four-level scale) and the public was advised to stay 2 km away from the active crater and 3.5 km away from the N crater wall opening.

Report for Mayon
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported increased seismic activity at Mayon and new lava at the summit in December. Photos of the summit dome on 8 and 10 December revealed that dark lava spines had been recently extruded. The seismic network detected an increase in rockfalls from an average of three events per day in 2025 to an average of 16 events per day in December, coincident with the extrusion. The Alert Level remained at 1 (on a 0-5 scale); the public was warned to stay out of the 6-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.

Report for Taal
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported eruptive activity at Taal during 3-9 December. The seismic network recorded 3-9 daily volcanic earthquakes along with periods of volcanic tremor lasting one minute long to over 13 hours long. Daily gas-and-steam emissions with variable densities generally rose as high as 600 m above the crater rim and drifted mainly SW and NE. Minor phreatic and phreatomagmatic events at 0058 and 0104 on 4 December produced plumes that rose 1.2 km above the crater rim and drifted SW. Both events lasted two minutes. The second event ejected incandescent ballistics 300 m above the lake. Sulfur dioxide emissions averaged 466 tonnes per day on 5 December. The Alert Level remained at 1 (on a scale of 0-5); PHIVOLCS reminded the public that the entire Taal Volcano Island (TVI) was a Permanent Danger Zone (PDZ) and recommended that the Main Crater and areas along the Daang Kastila fissure should remain prohibited. Pilots were warned to avoid flying over TVI.

Report for Suwanosejima
The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 28 November-5 December. Incandescence was observed nightly in webcam images. Eruption plumes rose as high as 700 m above the crater rim. The Alert Level remained at 2 (the second level on a five-level scale) and the public was warned to be cautious within 1.5 km of the crater.

Report for Aira
The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 2-8 December with 11 eruptive events and nine explosions. Ash plumes rose as high as 2.2 km above the crater rim and large blocks were ejected as far as 700 m from the vent. Nightly crater incandescence was visible in webcam images. Sulfur dioxide emissions were characterized as high, averaging 2,300 tons per day on 5 December. Daily eruptive events produced ash plumes that rose 1-2.2 km above the crater rim and drifted NE and SE. Explosions at 1107, at 2046, at 2212, and at 2338 on 4 December, at 0654 and at 2229 on 5 December, at 0213 on 6 December, and at 2053 and at 184 on 8 December generated ash plumes that rose 600-1,700 m above the crater rim and drifted E and SE. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of both the Minimadake and Showa craters.

Report for Ahyi
On 5 December the US Geological Survey reported that signs of unrest at Ahyi Seamount were observed during the previous week. Single detections from Ahyi's direction were detected at underwater pressure sensors near Wake Island (about 2,270 km E of Ahyi) on 29 and 30 November. Slightly discolored water was seen a few hundred meters E of the seamount in high-resolution satellite images on 30 November. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale).

Report for Krasheninnikov
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that the eruption at Krasheninnikov continued during 28 November-4 December. A large thermal anomaly over the volcano was identified in satellite images during 28 November-2 December. Gas-and-steam plumes drifted 60 km NW on 30 November and 1 December. Satellite images showed active lava and continuing advancement of flows on the ENE flank during 22 November-6 December. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates and times are provided in Coordinated Universal Time (UTC); specific events are indicated in local time where specified.

Report for Bezymianny
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a large thermal anomaly over Bezymianny was identified in satellite images during 28 November-4 December. The Aviation Color Code remained at Yellow (the second lowest level on a four-level scale). Dates are reported in UTC; specific events are in local time where noted.

Report for Sheveluch
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported continuing eruptive activity at Sheveluch’s “300 years of RAS” dome on the SW flank of Old Sheveluch and at the Young Sheveluch dome during 27 November-4 December. Explosions on 27 November generated ash plumes that rose as high as 10 km (32,800 ft) a.s.l. and drifted as far as 655 km E. A thermal anomaly was identified in satellite images during 28 November-2 December; the volcano was obscured by weather clouds 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; specific events are in local time where noted.

Report for Great Sitkin
The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin’s summit crater during 2-9 December. Small earthquakes were detected by the seismic network along with occasional rockfall signals. Elevated surface temperatures were identified in satellite views during 4-7 December. Weather clouds obscured satellite and webcam views. AVO noted that the rate of lava effusion appeared to be declining gradually. 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).

Report for Kilauea
The Hawaiian Volcano Observatory (HVO) reported that the eruption within Kilauea’s Kaluapele summit caldera, characterized by episodic fountaining, incandescence, and intermittent spatter from craters along the SW margin of Halema’uma’u Crater, continued at variable levels during 2-9 December. During a helicopter overflight on 2 December volcanologists observed a spattering lava surface deep within the N vent. Incandescence at both the N and S vents was visible overnight during 2-5 December, and was accompanied by flames from burning gas (likely hydrogen gas) and occasional weak spattering. Persistent low-to-moderate tremor was punctuated by minor seismic tremor bursts suggestive of irregular gas pistoning at depth. Periods of gas pistoning became more frequent overnight during 4-5 December and incandescence at the N vent intensified. Spattering at the N vent increased by 0330 on 5 December. Large flames arose from the S vent and from a crack adjacent to the N vent.

During the episode of lava fountaining that ended on 25 November a new vent opened within the N vent; the original vent (the right vent) and a new vent to the left, separated by a septum of rock. Lava erupted from the N vent at 1250 on 5 December and lasted for about two minutes. Three more lava overflows, each lasting 10-20 minutes, occurred later that day during 1700-2000. A short lava overflow was recorded at 0235 on 6 December and was followed by continuous overflows at 0337. Most of the overflows came from the left vent, but by around 0700 the right vent also began overflowing, increasing the effusion rate and producing fountains. Lava fountains rose 5-20 m and produced ribbon-like flows onto the Halema’uma’u Crater floor. The S vent continued to glow and spatter intermittently but produced no overflows. Activity escalated and by 0845 sustained lava fountains at both the right and left vents of the N vent were 15-30 m high. Lava fountains rose from the S vent at 0849 and quickly reached 370 m high while the fountains at the N vent dropped to 150 m. All three vents were producing lava fountains, which was an extremely rare event. By 0940 the S vent fountains were about twice as high as the N vent fountains. The S vent became enlarged and produced fountains over 300 m tall that arced towards the S wall of the crater. Molten spatter and pumice from the S vent destroyed the “V3” streaming camera site, located within the closed area, just before 1000.

The eruption was sustained for about 12 hours with lava fountains rising as high as 370 m. The dual fountains at the N vent ceased at 1150 and the S vent ceased erupting at 2052. The fountains produced an estimated 12 million cubic meters of lava that covered 50-60% of the crater floor. The combined average eruption rate was an estimated 190 cubic meters per second with a peak of 1,000 cubic meters per second just before 1000 when fountains at the S vent rose to high levels. The associated eruption plume, composed of water vapor, sulfur dioxide gas, Pele's hair, reticulite and fine ash, rose 6.1 km (about 20,000 ft) above ground level. Tephra including Pele's hair and fine ash carried in lower levels of the plume fell in Pahala and other communities SW of the vents. Satellite imagery showed that the upper regions of the gas-and-ash cloud drifted E across lower Puna and reached an area well out to sea before turning S. Reticulite pieces up to about 75 mm fell along Chain of Craters Road E of the summit.

Both vents and the crack adjacent to the N vent were intermittently incandescent overnight during 6-9 December. Incandescent lava on the crater floor gradually cooled and went dark during 6-7 December, though spatter-fed flows on the slopes S of both vents remained partially incandescent and moved downslope through 9 December. 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).

Report for Popocatepetl
The Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity continued at Popocatépetl during 2-9 December. The seismic network recorded 3-70 long-period events per day, accompanied by steam-and-gas emissions with occasional minor ash content that drifted in various directions. In addition, the seismic network recorded 96 minutes of low-amplitude tremor during 7-8 December and 201 minutes of low-amplitude tremor consisting of 78 minutes of high-frequency tremor and 123 minutes of harmonic tremor during 8-9 December. According to the Washington Volcanic Ash Advisory Center (VAAC) ash plumes visible in webcam and satellite images on 3, 5, 7, and 9 December rose 5.6-6.1 km (18,500-20,000 ft) a.s.l. (about 400 m above the crater rim) and drifted in multiple directions. 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.

Report for Santa Maria
The Instituto Nacional de Sismología, Vulcanología, Meteorología e Hidrología (INSIVUMEH) reported high levels of ongoing eruptive activity at Santa Maria’s Santiaguito dome complex during 2-10 December, with continuing lava extrusion at Caliente dome. Daily explosions, 1-7 per hour when reported, generated gas-and-ash plumes that rose 800-900 m above the dome and drifted W and SW. Effusion of blocky lava and collapses of incandescent material produced incandescent block avalanches that descended the flanks. Ashfall was reported in areas downwind including San Marcos Palajunoj (8 km SW) and Loma Linda (7 km W) during 4-5 December.

Report for Poas
The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported that an explosive eruption at Poás occurred at 2234 on 6 December, generated an eruption plume that rose around 400 m above the crater rim, and ejected incandescent ballistics. The eruption lasted about five minutes. The Volcanic Alert Level remained at 2 (the second lowest level on a four-level scale).

Report for Nevado del Ruiz
The Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that eruptive activity at Nevado del Ruiz continued during 2-8 December, though weather conditions sometimes obscured visual observations. Seismic data indicated that events associated with fluid movement decreased in both number and intensity compared to the previous week. There were no confirmed ash emissions associated with the signals; gas-and-steam emissions rose as high as 1 km above the summit and drifted in various directions. Seismicity associated with rock fracturing was similar in number and intensity compared to the previous week. The earthquakes were low magnitude (up to M1) and mainly located at depths of 2-9 km below Arenas Crater and below the flanks within 12 km. Seismicity associated with activity at the lava dome was recorded on 4 December. Daily sulfur dioxide emissions fluctuated at low levels. Low-level thermal anomalies at the bottom of the crater were periodically identified in satellite images. The Alert Level remained at Yellow (the second level on a four-level scale).

Report for Purace
The Servicio Geologico Colombiano (SGC) reported continuing eruptive activity at Puracé during 2-9 December. Seismicity was characterized by tremor and long-period signals indicating fluid movement, periods of continuous tremor, and earthquakes indicating rock fracturing located at depths of 1-3 km. Daily gas-and-ash emissions rose 100-900 m above the summit and drifted downwind. On 3 December a temperature increase within the crater was identified in satellite data. During 2-3 December minor ashfall was reported in areas to the SE including Cristales and Agua Hirviendo. Ashfall on 3 December was reported in the Cristales area and Casa de Cabildo of Puracé (N), in Río Negro and Paletará council (16 km SW), in the Agua Hirviendo hot springs (11 km WNW), and in San Juan (NE). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public was warned to stay away from the crater.

Report for Reventador
The Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that eruptive activity continued at Reventador during 2-9 December. Seismicity included 57-88 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions, though transmission of the data was interrupted during 7-9 December. Daily ash-and-gas plumes visible in webcam and/or satellite images rose as high as 1.6 km above the crater rim and drifted in multiple directions. Minor ashfall was reported in the El Reventador sector of Sucumbíos Province (N and NE) during the morning of 3 December and in various areas of Napo province, including San Luis (8 km SE), Manuel Galindo (8 km SE), and the El Reventador parish during 5-9 December. Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at Orange (the second highest level on a four-color scale).

Report for Sangay
The Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that the eruption continued at Sangay during 2-9 December. The seismic network recorded 89-165 explosions each day. Ash-and-gas plumes were observed on most days in webcam and/or satellite images rising 300-900 m above the summit and drifting NE, E, and SE, though weather clouds often obscured views. Crater incandescence was visible during the morning of 5 December. The Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at Yellow (the second highest level on a four-color scale).

Report for Planchon-Peteroa
The Servicio Geológico Minero Argentino (SEGEMAR) reported that at 0944 on 4 December a gas-and-ash plume at Planchón-Peteroa rose 850 m above the crater rim and drifted NE. The plume dissipated near the summit. The Alert Level remained at Yellow (the middle level on a three-color scale). According to the Sistema y Servicio Nacional de Prevención y Repuesta Ante Desastres (SENAPRED) the communities of Molina (66 WNW), Curicó (68 km NW), Romeral (75 km NW), and Teno (68 km NW) continued to be under a “Preventive Early Warning” (since 18 July 2025) and that a security perimeter 4 km from the craters was in effect.