The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Thursday, these notices are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of eruptions during the week, but rather a summary of activity that meet selected criteria. Carefully reviewed, detailed reports are published in the Bulletin of the Global Volcanism Network.

The Wellington Volcanic Ash Advisory Center (VAAC) reported that ash-and-gas plumes from Ambae were identified in satellite and/or webcam images on 17 May rising to 1.8-3 km (6,000-10,000 ft) a.s.l. and drifting E and NW. The Alert Level remained at 3 (on a scale of 0-5), and the public was warned to stay outside of Danger Zone B, defined as a 3-km radius around the active vents in Lake Voui, and to stay away from drainages during heavy rains.

Sources: Vanuatu Meteorology and Geohazards Department (VMGD),Wellington Volcanic Ash Advisory Center (VAAC)

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported increased seismicity at Bulusan in a 20 May advisory, with a total of 442 volcano-tectonic (VT) earthquakes recorded by the seismic network since 1600 on 18 May. The VT earthquakes were associated with rock fracturing, with 55 of the events located at depths less than 5 km beneath the edifice. Very weak to moderate degassing was observed from active vents when the volcano was visible; sulfur dioxide emissions were at low levels, averaging 121 tonnes per day based on the most recent measurement on 22 April. Continuous GPS monitoring indicated inflation of the N flank since June 2025 and the upper W flank since January 2026, interpreted as slow pressurization due to shallow hydrothermal or tectonic processes. The Alert Level remained at 1 (the second lowest level on a scale of 0-5). The public was reminded not to enter the 4-km-radius Permanent Danger Zone (PDZ) and to exercise vigilance within the 2-km Extended Danger Zone (EDZ) on the SE sector. Pilots were warned not to fly close to the summit because of the potential of ash plumes from phreatic eruptions.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono?s Malupang Warirang Crater remained high after the 8 May eruption. During 9-16 May an average of 52 eruptive events per day were recorded with ash plumes rising 400-4,300 m above the summit and drifting NW, W, and SW. At 1838 on 17 May a gray-to-black ash plume rose 5 km above the summit and drifted SW, W, and NW. Additional eruptive events that same day rose 400-3,000 m above the summit and drifted those same directions. Ash plumes decreased slightly on 18 May, rising to 3,800 m above the summit, to 3,000 m above the summit on 19 May, and to 1,500 m above the summit on 20 May. The Alert Level remained at Level 2 (on a scale of 1-4) and the public was warned to stay 4 km away from the Malupang Warirang Crater.

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

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported an earthquake of magnitude 2.1 near Iya on 16 May 2026, followed by an increase in seismicity at Iya through 17 May. In general, white plumes rose as high as 200 m above the summit and drifted in multiple directions between 14-20 May. The Alert Level remains at level 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the active crater.

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

The Japan Meteorological Agency (JMA) reported that an eruption at Iodake Crater (at Satsuma Iwo-jima, a subaerial part of Kikai?s NW caldera rim) was recorded at 0207 on 17 May, the first since 29 December 2025. An ash-and-gas plume rose 400 m above the crater rim and drifted S. The report noted that volcanic earthquakes remained infrequent, and no notable changes detected before or after the eruption. No volcanic tremors were recorded. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to be cautious within 500 m away from Iodake Crater.

Source: Japan Meteorological Agency (JMA)

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported eruptive activity at Taal during 14-21 May. The seismic network recorded 3-15 daily volcanic earthquakes; the counts included 2-14 periods of tremor, each lasting 1-28 minutes, during 17-18 May. Daily diffuse gas-and-steam emissions rose as high as 2,400 m above the crater rim and drifted primarily SW with some W, NW, and NE drift. A minor phreatic eruption began at 0016 on 17 May, lasted for three minutes, and produced plumes that rose 300 m. 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.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

The Rabaul Volcano Observatory (RVO) reported that the eruption in the Central Bismarck Sea that began at around 0115 on 8 May (based on regional infrasound data) continued during 13-20 May. During 13-14 May, plumes of steam and gas of variable densities and vigor rose from the eruption site and drifted to the W and NW; plumes of discolored water drifted from the site as well. By 15 May steam-and-gas plumes were identified in satellite imagery originating from two separate vent areas approximately 2.5 km apart; the eastern area was about 1.5 km in diameter, and the western area was about 500 m in diameter. A M 5.4 earthquake was recorded at around 1113 on 15 May. During 15-16 May, pumice rafts identified in satellite images were producing thermal anomalies at up to 2 km from the source, suggesting that the rafts were initially thick. A 5-km-long area of thermal anomalies seen on 16 May, trending roughly WSW-ENE, was visible along the base of plumes; part of the thermal signature may have been from initially hot floating pumice. Small signatures indicating possible ash were detected on 16 May, though they were likely due to pumice pieces rapidly decompressing and disintegrating at the surface. Weather clouds obscured satellite views during parts of 15-17 May, making interpretations of the activity challenging, though data confirmed that the eruption remained submarine over this interval. During 18-20 May the steam plumes were more diffuse during previous days and drifted W and NW. Weak winds contributed to the plume rising to 5.5 km above the ocean?s surface. Plumes of discolored water drifted W, SW, and NW. According to a news article local fisherman observed and photographed the steam plumes, noting that there were dead fish nearby, and observing that ?[the eruption] sounds like thunder and the sea smells like metal burning."

Sources: Rabaul Volcano Observatory (RVO),Radio New Zealand

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that unrest activity increased at Awu. During 1-18 May, seismicity increased, with 24 deep volcanic earthquakes and 519 shallow volcanic earthquakes recorded over the period. White plumes rose 100-200 m above the lava dome. Shallow seismic swarms, each with 74 events, occurred on 4 May and 19 May (0000-1200). CVGHM/PVMBG raised the Alert Level to 3 (on a 4-level scale) at 1300 on 19 May 2026. The public was advised to stay at least 4 km from the crater center.

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

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported increasing activity at Bezymianny and an explosive eruption during 13-20 May. On 13 May the Aviation Color Code was raised to Orange (the second highest level on a four-level scale) due to hot avalanches descending the flanks and an intensifying thermal anomaly identified in satellite images. A gas-and-steam plume containing ash drifted 80 km SW at an altitude of 4 km (13,100 ft) a.s.l. Satellite images on 16 May indicated that hot avalanches continued to be generated from lava dome collapses. Ash plumes from the collapses drifted 40 km SE at an altitude of 4.5 km (14,800 ft) a.s.l. Activity escalated later that day at 1630, and by 2050 a large eruption cloud was visible in satellite images rising to 6.5 km (21,300 ft) a.s.l. and slowly drifting SE. Explosions on 17 May generated ash plumes that rose as high as 5 km (16,400 ft) a.s.l. and drifted SE. An explosive eruption that began at 1820 on 18 May produced ash plumes that rose 10 km (32,800 ft) a.s.l. and drifted ESE. A pyroclastic flow descended the E flank. The Aviation Color Code was raised to Red a few hours later at 2102. Hot avalanches continued to descend the flanks on 19 May, but no ash explosions were recorded; at 0424 the Aviation Color Code was lowered to Orange. The ash plume from the day before had drifted 500 km WNW. Lava effusion continued through 20 May, accompanied by gas-and-steam emissions and small hot avalanches. Dates are reported in UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported that eruptive activity at Fuego continued during 14-21 May. Daily Strombolian explosions recorded by the seismic network, at rates of 5-12 per hour when reported, generated gas-and-ash plumes that rose as high as 1 km above the summit and drifted as far as 40 km W and SW. Rumbling sounds, shock waves, and/or sounds associated with gas emissions were reported daily. Explosions occasionally ejected incandescent material as high as 300 m above the summit. Incandescent block avalanches descended the Seca (W), Taniluyá (SSW), Ceniza (SSW), Las Lajas (SE), and Honda (E) drainages, sometimes reaching vegetated areas. Ashfall was reported in areas downwind, including Panimaché I and II (8 km SW), Yepocapa (8 km WNW), Morelia (10 km SW), El Porvenir (11 km SW), and La Rochela (7.5 km SSW). A weak to moderate lahar descended the Ceniza drainage on 17 May at 1840 that carried branches, tree trunks, and boulders ranging from 30 cm to 3 m in diameter. INSIVUMEH made recommendations to avoid being in or near ravines during rainfall on the volcano and noted that it is prohibited to approach the ?La Meseta? and ?El Camelión? areas near the summit.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin?s summit crater during 14-20 May. Small earthquakes and rockfalls associated with the activity were periodically detected in seismic data. Lava-dome growth and resulting rockfalls were concentrated at the E part of the flow based on radar data. Weather clouds often prevented webcam and satellite observations. 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)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity at Ibu continued during 14-20 May, with daily eruptive events recorded by the seismic network and by visual observation. Daily gray ash plumes rose 200-1,000 m above the summit and drifted in multiple directions. Incandescence at the summit was visible in several 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.

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