Report for Stromboli
The Sezione di Catania - Osservatorio Etneo (INGV) reported that eruptive activity continued at Stromboli during 26 May-1 June. Webcam images showed Strombolian activity at four vents in Area N within the upper part of the Sciara del Fuoco and from at least two vents in Area C-S (South-Central Crater) on the crater terrace. The vents in Area N continued to produce low- to medium-intensity explosions at a rate of 4-8 events per hour, ejecting lapilli and bombs less than 150 m above the vents. Low- to medium-intensity explosions at the vents in Area C-S ejected ash, bombs, and lapilli above the vent at a rate of 3-5 events per hour. The Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile.

Report for Etna
The Sezione di Catania - Osservatorio Etneo (INGV) reported that tremor amplitude at Etna began to increase starting at around 0000 on 2 June and reached high levels by 0250. Infrasound activity slightly increased at around 0230 and around 0350 Strombolian activity at the SE Crater was visible in webcam images. The Aviation Color Code was raised to Yellow (the second highest color on a four-color scale) at 0323, to Orange at 0402, and to Red at 0839. Ash emissions at this time were confined to the summit area, though Strombolian activity intensified through the morning and became almost continuous. Lava overflowed the E rim of the crater and produced a small lava flow towards the Valle del Bove. A larger flow traveled S. Infrasound activity was both frequent and intense. Lava fountaining began at SE Crater at around 1000 and both lava flows advanced; the flows branched and were 2 km long. Ash plumes rose above the summit and drifted W. Minor ashfall was reported in the Piano Vetore area (6 km SSW) prior to 1100.

A fissure opened on the upper NE flank of SE Crater at around 1100 and produced a lava flow that advanced N, according to the Associazione Italiana di Vulcanologia ETS (AIV ETS). Emissions of gas, ash, and white-to-reddish-brown steam rose from that same area. The emissions progressively intensified for 20 minutes. INGV noted that at 1124 a pyroclastic flow was likely generated from a collapse of material at the N side of the SE Crater cone and traveled NE, reaching the N wall of the Valle del Leone (the upper part of the Valle del Bove). AIV ETS stated that the pyroclastic flow interacted explosively with buried snow and traveled 2 km in one minute. Ash rose along the pyroclastic flow to about 3 km above the summit and was visible across eastern Sicily. According to INGV fine reddish ash drifted WNW and fell in Cesarò (27 km WNW) and Bronte (15 km WNW). A lava flow from the base of the N flank of SE Crater advanced N. News article noted that many tourists were on the flanks and were seen running away from the pyroclastic flow; tourist visits to the volcano were halted. About 20 percent of flights into Catania were delayed. Strombolian activity decreased during the afternoon and at 1600 the Aviation Color Code was lowered to Orange. Minor ash emissions continued but dispersed near the summit area; the Aviation Color Code was lowered Yellow at 1656. Activity ceased and at 2011 the Aviation Color Code was lowered to Green.

Report for Gaua
On 28 May the Vanuatu Meteorology and Geohazards (VMGD) reported that unrest continued at Gaua. Steam and/or gas emissions from the vent were visible in satellite images during the month; sulfur dioxide emissions were identified in images on 19 and 24 May. A moderate-level thermal anomaly was identified in a satellite image on 17 May, indicative of increased surface temperatures. The Alert Level remained at 2 (on a scale of 0-5) and the public was warned to stay away from the main cone.

Report for Ambae
On 28 May the Vanuatu Meteorology and Geohazards Department (VMGD) reported ongoing unrest at Ambae during the month of May. Steam and/or gas emissions from the active vents were visible in webcam images on 1 May. That same day a thermal anomaly was identified in a satellite image. Sulfur dioxide emissions were detected in satellite data during 1-4, 8-21, and 24-26 May. Seismic data also confirmed ongoing unrest. The Alert Level remained at 2 (on a scale of 0-5), and the public was warned to stay outside of the Danger Zone, defined as a 2-km radius around the active vents in Lake Voui, and away from drainages during heavy rains.

Report for Ambrym
On 28 May the Vanuatu Meteorology and Geohazards Department (VMGD) reported ongoing unrest at Ambrym during the month of May. Webcam images recorded volcanic emissions rising from Benbow Crater on 9 May. Seismic data confirmed ongoing unrest. The Alert Level remained at 2 (on a scale of 0-5). VMGD warned the public to stay outside of Permanent Danger Zone A, defined as a 1-km radius around Benbow Crater and a 2-km radius around Marum Crater, and to stay 500 m away from the ground cracks created by the December 2018 eruption.

Report for Lopevi
On 28 May the Vanuatu Meteorology and Geohazards Department (VMGD) reported that during the month seismic data confirmed continuing unrest at Lopevi. Small fumarolic steam plumes were continuously emitted from the summit crater based on a webcam image from 1 May. Low-level thermal anomalies were identified in satellite images on 1 and 20 May, indicative of increased surface temperatures. The Alert Level remained at 2 (on a scale of 0-4).

Report for Yasur
On 28 May the Vanuatu Meteorology and Geohazards Department (VMGD) reported that activity at Yasur continued at a level of “major unrest,” as defined by the Alert Level 2 status (on a scale of 0-5). Satellite and webcam images indicated that explosions continued, producing emissions of gas, steam, and/or ash. Sulfur dioxide gas emissions were identified in satellite images during 3, 5-7, 10, 13-16, 18-24, and 26 May, and low-level thermal anomalies were identified during 3, 5, 7, 13-14, and 26 May. Seismic data confirmed continuing volcanic activity with explosions that were occasionally strong. The report warned that ejected material from explosions could fall in and around the crater. The public was reminded to not enter the restricted area within 600 m around the boundaries of the Permanent Exclusion Zone, defined by Danger Zone A on the hazard map.

Report for Marapi
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Marapi (on Sumatra) continued during 28 May-3 June. White plumes rose 100-400 m above the summit and drifted in multiple directions on most days. An eruptive event at 2236 on 30 May was recorded by the seismic network, though a plume was not visible. White-and-gray plumes rose 150-300 m above the summit and drifted E and SE on 31 May. 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 Merapi
The Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG) reported that the eruption at Merapi (on Java) continued during 23-29 May. Seismicity remained at high levels. The SW lava dome produced 30 lava avalanches that traveled as far as 1.8 km SW down the Bebeng drainage, 12 that traveled as far as 1.8 km SW down the Krasak drainage, and 33 that traveled as far as 2 km W down the Sat/Putih drainage. Small morphological changes to the SW lava dome resulted from continuing effusion and minor collapses. 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
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru during 21-27 May, with often multiple daily eruptive events recorded by the seismic network. White-and-gray ash plumes rose 400-1,200 m above the summit and drifted in multiple directions; no plumes were visible on 31 May. The Alert Level remained at 2 (the second lowest level on a scale of 1-4). The public was warned to stay at least 3 km away from the summit in all directions, 8 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 13 km from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Report for Lewotobi
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that daily white steam-and-gas plumes rose as high as 1 km above the summit of Lewotobi Laki-laki during 28 May-3 June. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 6 km away from the center of Laki-laki.

Report for Lewotolok
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruption at Lewotolok was ongoing during 28 May-3 June. Daily gray or white-to-gray ash plumes rose as high as 1 km above the summit of the cone and drifted NW and W. Clear nighttime webcam images showed incandescent material at the summit cone, being ejected above the summit cone, and on the upper S flank. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the vent and 2.5 km away on the S, SE, and W flanks.

Report for Dukono
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 14-20 May. Daily white-and-gray or white, gray, and black gas-and-ash plumes rose 900-1,900 m above the summit and drifted NW, W, and S. The emissions were described as ongoing through the week. Residents 10-11 km away felt vibrations from the activity on 29 May and occasional banging sounds were heard at the same distances during 29-30 May. Faint rumbling was heard at the observation post, 11 km N, during 31 May-1 June. 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.

Report for Ibu
The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 14-20 May. Daily gray or white-to-brown ash plumes rose as high as 1 km above the summit and drifted S, SW, NW, and NE. Nighttime crater incandescence was visible in some webcam images. 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.

Report for Kanlaon
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon during 27 May-3 June. The seismic network recorded 5-38 daily volcanic earthquakes. Daily sulfur dioxide emissions ranged from 300 to 1,844 tonnes per day. Gas-and-steam emissions of variable densities generally rose 75-750 m above the crater rim, though they reached 1.2 km on 2 June, and drifted SE, NE, NW, and SW. During 1338-1407 on 2 June a grayish ash plume rose 1.2 km above the summit and drifted W. The Alert Level remained at 3 (on a scale of 0-5); the public was warned to stay 6 km away from the summit and pilots were warned not to fly close to the volcano.

Report for Taal
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing unrest at Taal during 27 May-3 June. There were 0-20 daily volcanic earthquakes and a few periods of tremor that lasted 1-10 minutes long during 27-30 May and on 2 June; no volcanic earthquakes were recorded during 31 May-1 June. Daily gas-and-steam emissions that were sometimes voluminous rose 900-1,500 m above the crater rim and drifted NW and NE. Hot fluids upwelling in the lake were periodically observed. Sulfur dioxide emissions averages were 1,351-6,289 tonnes per day on most days. A minor phreatic eruption lasting four minutes occurred on 29 May. The Alert Level remained at 1 (on a scale of 0-5); PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ) and recommended that the Main Crater and areas along the Daang Kastila fissure should remain prohibited.

Report for Suwanosejima
The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima's Ontake Crater continued during 26 May-2 June. Incandescence was observed nightly in webcam images. No explosions were detected, though plumes from eruptive events rose 600 m above the crater rim. Ashfall was reported by the Suwanosejima Branch of the Toshima Village Office (3.5 km SSW). 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 28 May-2 June. Very small eruptive events were recorded during 26-28 May. Sulfur dioxide emissions measured during a field survey on 28 May were extremely high, averaging 3,500 tons per day. An explosion at 1537 on 29 May produced an ash plume that rose 1.5 km above the crater rim, going into weather clouds, and ejected large blocks 700 m from the rim. Nighttime crater incandescence was visible during 30 May-2 June. Explosions at 1727 and 2058 on 30 May and at 1610 on 1 June generated ash plumes that rose 3-3.5 km above the crater rim and drifted S and SE and ejected large blocks as far as 1.1 km from the crater rim. An explosion at 2341 on 2 June ejected large blocks as far as 1 km from the crater rim; details about any emissions were unknown. 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
Unrest at Ahyi Seamount continued during 24-30 May. A small plume of discolored water in the vicinity of the seamount was identified in a satellite image on 28 May, indicating possible submarine activity. Possible infrasound signals coming from the direction of Ahyi were identified in data from underwater pressure sensors near Wake Island (about 2,270 km E) on 29 May. 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 Karymsky
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that moderate activity continued at Karymsky during 23-29 May. A thermal anomaly over the volcano was identified in satellite images during 22, 25, and 27-28 May; weather clouds obscured views on other days. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC; specific events are in local time where noted.

Report for Klyuchevskoy
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a daily bright thermal anomaly at Klyuchevskoy was identified in satellite images during 23-29 May. Explosions at 1945 on 28 May produced ash plumes that rose 6.5 km (21,300 ft) a.s.l., or about 1.7 km above the summit, and drifted 5 km SW. The ash plumes were identified in webcam images. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale) at 2000. Dates are based on UTC times; specific events are in local time where noted.

Report for Sheveluch
The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that lava extrusion may have continued at Sheveluch’s “300 years of RAS” dome on the SW flank of Old Sheveluch and at the Young Sheveluch dome during 23-29 May. Thermal anomalies over the domes were identified almost daily in satellite images; weather clouds sometimes obscured views. The Far Eastern Branch of the Russian Academy of Sciences (FEB RAS) reported that minor ash plumes rising as high as 3 km (10,000 ft) a.s.l. drifted NW, W, SW, and SE during 23, 25-26, and 28-29 May. 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 28 May-3 June. Small daily earthquakes were detected by the seismic network. Weather clouds often obscured views of the volcano, though weakly elevated surface temperatures consistent with lava effusion were identified in satellite images on 29 May and 2 June and minor steaming was visible in satellite images on 30 May and 2 June. A 3 June radar image confirmed growth to the SE. 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 Yellowstone
The Yellowstone Volcano Observatory (YVO) reported that a small hydrothermal explosion occurred at Black Diamond Pool, in Yellowstone’s Biscuit Basin thermal area, at 2039 on 31 May. An analysis of the periodic webcam images (taken every 15 minutes) revealed changes at the pool that same evening; the nature and timing of the changes was not reported. The event was the first at Black Diamond Pool that had been captured on video since the hydrothermal explosion on 23 July 2024, though there was evidence from other monitoring data and eyewitnesses that sporadic eruptions had occurred several times since that event. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest 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 and intermittent spatter at two vents along the SW margin of Halema’uma’u Crater, continued at variable levels during 28 May-3 June. Night incandescence and occasional spattering was visible from both the N and S vents during the week, though the incandescence was stronger at the N vent. Gas emissions rose from both vents. Strands of Pele’s hair were present throughout the summit area of Hawai’i Volcanoes National Park and surrounding communities. 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 27 May-3 June. The seismic network recorded 42-70 long-period events per day, accompanied by steam-and-gas emissions with occasional ash content. In addition, the seismic network recorded daily periods of tremor, sometimes characterized by harmonic and high-frequency signals, lasting from 41 minutes to three hours and 52 minutes. According to the Washington VAAC an ash plume was visible in webcam and satellite images at 1646 on 30 May rising 5.8 km (19,000 ft) a.s.l. (about 400 m above the crater rim) and drifting N. Steam-and-gas plumes with minor ash content were visible in webcam images on 2 June rising 5.8 km a.s.l. and drifting NW and SW. 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 27 May-3 June with continuing lava extrusion at Caliente dome. Daily weak and moderate explosions, as many as three per hour when reported, generated gas-and-ash plumes that rose as high as 1 km above the dome and drifted as far as 40 km in various directions. Effusion of blocky lava and collapses of material produced block avalanches that descended multiple flanks; the collapsed material sometimes produced short pyroclastic flows that reached the base of Caliente cone. Incandescence was visible at Caliente dome and upper part of the SW flank lava flow. Ashfall was reported in areas downwind including San Marcos (10 km SW), Loma Linda (7 km W), Palajunoj (17 km SSW), Finca Monte Bello (6 km WSW), and Monte María during 27-31 May.

Report for Fuego
The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported continued eruptive activity at Fuego during 27 May-3 June. Daily explosions were recorded by the seismic network at rates of 3-7 per hour when reported. The explosions generated daily gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted as far as 30 km NW, W, and SW. Incandescent material was occasionally observed at night being ejected 100-150 m above the summit. Rumbling sounds and shock waves were occasionally reported. Explosions sometimes generated block avalanches that descended multiple flanks, sometimes reaching vegetated areas. Ashfall was reported in Panimache I and II (8 km SW), Morelia (10 km SW), Santa Sofia (12 km SW), El Porvenir (11 km SW), Finca la Asunción (12 km SW), and surrounding areas during 27-28 May and in areas downwind including Panimache I and II and Yepocapa (8 km WNW) during 1-2 June.

Report for Rincon de la Vieja
The Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported that occasional, small, phreatic eruptions at Rincón de la Vieja were recorded during 28 May-3 June. At 1546 on 31 May an explosive event recorded by the seismic network produced a white plume that rose 3 km above crater rim and drifted W. Two additional brief (around 1 minute long) phreatic events were recorded at 0642 on 1 June and at 0205 on 2 June. The first event generated a white plume with no ash that rose 1.5 km and drifted W; the plume from the second event was not visible. Sulfur dioxide emissions peaked near 1,000 tonnes per day in association with each of the three events.

Report for Poas
The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported continuing gas-and-steam emissions at Poás during 28 May-3 June. Variable sulfur dioxide gas emissions were higher during the last week of May compared to the previous week, but not as high as peak emissions at the end of April. Incandescence continued to be visible and detected in infrared webcam views at Boca A vent. Minor inflation was detected on some days and no clear trend was apparent on others. At 1022 on 1 June a gas-and-steam plume with minor ash content rose 1 km and drifted W. Gas-and-steam emissions continued during 2-3 June; the plume was tinted blue due to a high concentration of sulfur dioxide gas. The volcano’s Alert Level remained at 3 (the second highest level on a four-level scale).