The Weekly Volcanic Activity Report: June 18-24, 2026

New activity/unrest: Asosan, Japan | Bagana, Papua New Guinea | Krakatau, Indonesia | Titan Ridge, Papua New Guinea | Tokachidake, Japan.

New activity/unrest

Asosan, Japan

32.8849°N, 131.085°E; Elev. 1,592 m

The Japan Meteorological Agency (JMA) reported that the amplitude of volcanic tremors at Asosan began to increase at around 0900 on 21 June and reached a high level, signaling increasing unrest; the amplitude decreased around three hours later. During a field survey that same day scientists measured a high sulfur dioxide emission rate of 1,700 tons per day (t/d), increased from 900 t/d on 16 June. White plumes rose as high as 800 m above the Nakadake Crater rim. At 1600 the Alert Level was raised to 2 (on a scale of 1-5) and the public was warned that eruptive products may impact areas within 1 km of the crater. The amplitude of volcanic tremors increased at around 0150 on 22 June and was followed by an ejection of material visible in webcam images that fell back into the crater and a white plume rising 600 m above the crater rim.

Geological summary: The 24-km-wide Asosan caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 km3 of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Nakadake, is one of Japan’s most active volcanoes. It was the location of Japan’s first documented historical eruption in 553 CE. The Nakadake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 CE. Historical eruptions have largely consisted of basaltic to basaltic andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Nakadake is accessible by toll road and cable car, and is one of Kyushu’s most popular tourist destinations.

Bagana, Papua New Guinea

6.137°S, 155.196°E; Elev. 1,855 m

The Autonomous Bougainville Government reported that ash-and-gas plumes rose from Bagana at 2358 on 19 June and as a result the Rabaul Volcanological Observatory (RVO) increased the Alert Level to 1. The ash plume drifted NW, causing widespread ashfall in villages located in the Rotokas Constituency in the Wakunai District and in Sirivai and Atsinima (28 km W) in the Torokina District. A thin layer of ash was deposited on rooftops, on food crops, in vegetated areas, and in rivers, creeks, and water catchment systems.

Geological summary: Bagana volcano, in a remote portion of central Bougainville Island, is frequently active. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although occasional explosive activity produces pyroclastic flows. Lava flows with tongue-shaped lobes up to 50 m thick and prominent levees descend the flanks on all sides.

Krakatau, Indonesia

6.1009°S, 105.4233°E; Elev. 285 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increasing unrest at Krakatau. Sulfur dioxide emissions began to be detected in satellite data on 1 June and thermal anomalies were identified starting on 10 June. Emissions at the active crater intensified. The seismic network recorded an increase in shallow earthquake activity, specifically signals indicating gas-and-steam emissions, hybrid/multiphase events, and low-frequency events; the number of these signals notably increased during 18-19 June, averaging more than 50 events per day. Crater incandescence was visible in a webcam image at 2313 on 19 June. Though there was an increase in shallow activity, there were no deep volcanic earthquakes nor ground deformation detected. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 2 km away from the active crater.

Geological summary: The renowned Krakatau (frequently misnamed as Krakatoa) volcano lies in the Sunda Strait between Java and Sumatra. Collapse of an older edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of that volcano are preserved in Verlaten and Lang Islands; subsequently the Rakata, Danan, and Perbuwatan cones were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption caused more than 36,000 fatalities, most as a result of tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former Danan and Perbuwatan cones. Anak Krakatau has been the site of frequent eruptions since 1927.

Titan Ridge, Papua New Guinea

3.03°S, 147.78°E; Elev. -1,300 m

Satellite images at Titan Ridge were mostly cloudy over the vent and surrounding areas on 19 and 24 June, though plumes of light-green discolored water were visible drifting around 75 km W and around 100 km SW, respectively.

Geological summary: SOFAR signals resembling those produced at known submarine eruptions were recorded in January 1972 in the central Bismarck Sea (Johnson et al., 1981). The source of the signals was at the junction of two segments of the N margin of the South Bismarck plate. The more easterly of these segments is a transform fault, whereas the more westerly is an area of oblique active seafloor spreading. The signals were detected by a seismic station on nearby Manus Island, as well as at hydrophone stations on Wake and Midway Islands in the central Pacific. During the eruption in 2026 the “Titan Ridge” name was proposed by local residents. The general story of the Titan (pronounced Tee-Tahn) people is that their island home got devastated and reduced to the Circular Reef (~40 km SSW) due to an uncertain natural phenomenon; they drifted for awhile before they settled, and most of the Titan villages are now mainly along the south coast of Manus Island.

Tokachidake, Japan

43.418°N, 142.686°E; Elev. 2,077 m

The Japan Meteorological Agency (JMA) reported intensifying unrest at Tokachidake. Deformation data recorded persistent inflation at shallow depths starting in March. Seismicity near Crater 62-2 began increasing in April with spikes in the number of events occasionally occurring in May and June. Field surveys conducted on 28 April and 10 June revealed sulfur dioxide emission rates of 1,200 and 1,400 tons per day, respectively; these levels were higher than those in March. Beginning in April monitoring webcams recorded faint incandescence from Crater 62-2, possibly from high-temperature gas emissions and the combustion of sulfur. During 16-17 June field visits scientists observed high-temperature volcanic gas rising from the 62-2 Crater and the Furiko-sawa fumarole area; the fumarolic area had expanded and was releasing a larger volume of gases. They also observed repeated ejections of hot, muddy water from a part of the crater floor. At 1100 on 18 June the Alert Level was raised to 2 (on a scale of 1-5) and the public was warned that eruptive products may impact areas within 1.5 km of the crater.

Geological summary: Tokachidake volcano consists of a group of dominantly andesitic stratovolcanoes and lava domes arranged on a NE-SW line above a plateau of welded Pleistocene tuffs in central Hokkaido. Numerous explosion craters and cinder cones are located on the upper flanks of the small stratovolcanoes, with the youngest Holocene centers located at the NW end of the chain. Frequent historical eruptions, consisting mostly of mild-to-moderate phreatic explosions, have been recorded since the mid-19th century. Two larger eruptions occurred in 1926 and 1962. Partial cone collapse of the western flank during the 1926 eruption produced a disastrous debris avalanche and mudflow.

Ongoing activity

Aira, Japan

31.5772°N, 130.6589°E; Elev. 1,117 m

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 15-22 June. Very small eruptive events were detected during 15-19 June, and crater incandescence was visible in nighttime webcam images. An explosion at 1855 on 21 June produced an ash plume that rose as high as 1.5 km above the crater rim and drifted SE and ejected large blocks 300-500 m from the vent. 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 Minamidake and Showa craters.

Geological summary: The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan’s most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim and built an island that was joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4,850 years ago, after which eruptions took place at Minamidake. Frequent eruptions since the 8th century have deposited ash on the city of Kagoshima, located across Kagoshima Bay only 8 km from the summit. The largest recorded eruption took place during 1471-76.

Ambae, Vanuatu

15.389°S, 167.835°E; Elev. 1,496 m

The Wellington Volcanic Ash Advisory Center (VAAC) reported that ash-and-gas plumes from Ambae were identified in satellite images on 20 June rising as high as 3.7 km (12,000 ft) a.s.l. and drifting W. Steam emissions were visible the next day. 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.

Geological summary: The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone with numerous scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Dukono, Indonesia

1.6992°N, 127.8783°E; Elev. 1,273 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 18-24 June. White-to-gray ash plumes rose 300-1,000 m above the summit and drifted in multiple directions on most days; no emissions were observed on 22 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.

Geological summary: The Dukono complex in northern Halmahera is on an edifice with a broad, low profile containing multiple peaks and overlapping craters. Almost continuous explosive eruptions, sometimes accompanied by lava flows, have occurred since 1933. During a major eruption in 1550 CE, a lava flow filled in the strait between Halmahera and the Gunung Mamuya cone, 10 km NE. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also had reported eruptions.

Fuego, Guatemala

14.4748°N, 90.8806°W; Elev. 3,799 m

The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported that eruptive activity at Fuego continued during 17-24 June. Daily Strombolian explosions recorded by the seismic network, at rates of 2-18 per hour when reported, generated gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted as far as 40 km NW and W. Rumbling sounds, shock waves, and/or sounds associated with explosions were reported daily. Explosions ejected incandescent material as high as 300 m above the summit and onto the flanks, causing incandescent block avalanches to descend the flanks; notably they went down the Seca (W), Taniluyá (SSW), Ceniza (SSW), Las Lajas (SE), and Honda drainages, sometimes reaching vegetated areas. Ashfall was reported in communities on the W flank on a few of the days. Rainfall triggered lahars that descended the Seca drainage on 18 and 22 June, and the Ceniza drainage on 19 June. The lahars were composed of a mixture of water, fine volcanic material, tree branches and trunks, and blocks measuring from 30 cm to 3 m in diameter.

Geological summary: Volcán Fuego, one of Central America’s most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

Great Sitkin, United States

52.076°N, 176.13°W; Elev. 1,740 m

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin’s summit crater during 17-24 June. Seismicity was low and small rockfalls were occasionally detected. Slightly elevated surface temperatures were visible in satellite images during most of the week. Webcam images were often obscured by weather clouds, though steaming at the summit area was visible during 19-20 June. 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).

Geological summary: The Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger volcano capped by a small, 0.8 x 1.2 km ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an older edifice and produced a submarine debris avalanche. Deposits from this and an even older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano. The summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 m. The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Eruptions have been recorded since the late-19th century.

Ibu, Indonesia

1.4941°N, 127.6324°E; Elev. 1,357 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity at Ibu continued during 18-24 June, with daily eruptive events recorded by the seismic network. Daily gray or white-to-gray ash plumes rose 200-800 m above the summit and drifted in multiple directions. Incandescence at the summit was visible in 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.

Geological summary: The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, has contained several small crater lakes. The 1.2-km-wide outer crater is breached on the N, creating a steep-walled valley. A large cone grew ENE of the summit, and a smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. The first observed and recorded eruption was a small explosion from the summit crater in 1911. Eruptive activity began again in December 1998, producing a lava dome that eventually covered much of the floor of the inner summit crater along with ongoing explosive ash emissions.

Kanlaon, Philippines

10.4096°N, 123.13°E; Elev. 2,422 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon during 17-24 June. The seismic network recorded 1-9 daily volcanic earthquakes; on 17 June the counts included four periods of volcanic tremor lasting 18-43 minutes. Sulfur dioxide emissions ranged from 1,152 to 3,418 tonnes per day. Volcanic emissions generally rose as high as 900 m above the summit and drifted WSW and SW; weather clouds obscured views on 23 June. There were 2-3 daily periods of ash emissions during 17 and 19-20 June, each lasting as short as five minutes to as long as one hour and 22 minutes. Specifically, the webcam recorded grayish ash emissions at 0332 and 0535 on 19 June rising 300 m above the crater rim and drifting SW. The Alert Level remained at 2 (on a scale of 0-5); the public was warned to stay out of the 4-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.

Geological summary: Kanlaon volcano (also spelled Canlaon) forms the highest point on the Philippine island of Negros. The massive andesitic stratovolcano is covered with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km SW from Kanlaon. The summit contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller but higher active vent, Lugud crater, to the south. Eruptions recorded since 1866 have typically consisted of phreatic explosions of small-to-moderate size that produce minor local ashfall.

Kavachi, Solomon Islands

8.991°S, 157.979°E; Elev. -20 m

Yellow-green discolored water in the vicinity of the submarine Kavachi volcano was periodically visible in satellite images during May-June. Discolored water was visible in images on 6, 9, 24, 26, and 29 May, and on 18 June, but not visible in images on 19 May, 13 June, or 15 June.

Geological summary: Named for a sea-god of the Gatokae and Vangunu peoples, Kavachi is located in the Solomon Islands south of Vangunu Island. Sometimes referred to as Rejo te Kvachi (“Kavachi’s Oven”), this shallow submarine basaltic-to-andesitic volcano has produced ephemeral islands up to 1 km long many times since its first recorded eruption during 1939. Residents of the nearby islands of Vanguna and Nggatokae (Gatokae) reported “fire on the water” prior to 1939, a possible reference to earlier eruptions. The roughly conical edifice rises from water depths of 1.1-1.2 km on the north and greater depths to the SE. Frequent shallow submarine and occasional subaerial eruptions produce phreatomagmatic explosions that eject steam, ash, and incandescent bombs. On a number of occasions lava flows were observed on the ephemeral islands.

Kilauea, United States

19.421°N, 155.287°W; Elev. 1,222 m

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 18-24 June. Gas plumes rose from both the N and S vents through the week. Moderate-to-strong incandescence persisted at the S vent and large flames, likely caused by the ignition of volcanic gases escaping the vent were observed. Incandescence at the N vent was variable in intensity and intermittent. The Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale) and the Aviation Color Code remained at Yellow (the second lowest color on a four-color scale).

Geological summary: Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Kupreanof, United States

56.011°N, 159.797°W; Elev. 1,895 m

The Alaska Volcano Observatory (AVO) reported that unrest at Kupreanof continued through 24 June characterized by gas emissions, seismic activity, and deformation. Shallow seismicity remained at elevated levels with more than 30 earthquakes of magnitudes of 1 or greater detected since 12 May, when the Alert Level was first raised. The largest events during the current phase of unrest, which began in February, occurred on 15 and 16 June and had magnitudes of 3.2 and 3.6, respectively. Sulfur dioxide emissions were detected in satellite data on 13 days during 12 May-22 June with calculated emission rates of 100-800 tons per day, similar to the rate of emissions detected since April. These elevated emission rates were consistent with degassing of new, relatively shallow, magma beneath the volcano. Satellite interferometric radar (InSAR) ground deformation data was collected in mid-June following sufficient snow melt. A comparison with data from 30 September 2025, before snow covered the area, indicated that ground uplift around the volcano occurred sometime in the past eight months. The source depth of the inflation signal was estimated at 6 km below sea level, consistent with a magmatic intrusion and in agreement with the seismic and gas data. The Volcano Alert Level remained at Advisory (the second level on a four-level scale) and the Aviation Color Code remained at Yellow (the second color on a four-color scale).

Geological summary: Kupreanof is the largest and NE-most of a group of five relatively closely spaced Quaternary volcanic centers opposite Stepovak Bay. A debris flow or block-and-ash flow with possible juvenile fragments descended a late-Pleistocene valley south of the volcano. This stratovolcano displays vigorous fumarolic activity, and although a “grayish-brown ash horizon” extending 15 km was reported by a pilot in 1987 after emissions from a SSW-flank solfatara field, the cause of this event is uncertain.

Langila, Papua New Guinea

5.525°S, 148.42°E; Elev. 1,330 m

The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume from Langila rose to 2.1 km (7,000 ft) a.s.l. and drifted NW on 18 June based on satellite images.

Geological summary: Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower E flank of the extinct Talawe volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the N and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.

Lewotobi, Indonesia

8.542°S, 122.775°E; Elev. 1,703 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity continued at Lewotobi Laki-Laki during 18-24 June. Multiple daily gray ash plumes rose 300-1,000 m above the summit and drifted in multiple directions. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the center of Laki-Laki.

Geological summary: The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the “husband and wife”). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan.

Lewotolok, Indonesia

8.274°S, 123.508°E; Elev. 1,431 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported ongoing eruptive activity at Lewotolok during 18-24 June. Daily white plumes rose as high as 300 m above the summit. White-and-gray or gray ash plumes rose 300-800 m above the summit and drifted W during 18-19 and 22 June. Webcam images from 1925 on 21 June and 1954 on 23 June showed incandescent material being ejected above the summit and onto the flanks. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit.

Geological summary: The Lewotolok (or Lewotolo) stratovolcano occupies the eastern end of an elongated peninsula extending north into the Flores Sea, connected to Lembata (formerly Lomblen) Island by a narrow isthmus. It is symmetrical when viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano’s high point. Many lava flows have reached the coastline. Eruptions recorded since 1660 have consisted of explosive activity from the summit crater.

Mayon, Philippines

13.257°N, 123.685°E; Elev. 2,462 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported that the eruption at Mayon continued during 18-24 June, characterized by lava effusion, periodic pyroclastic density currents (PDCs), incandescent rockfalls, and occasional ash-and-gas plumes. Emissions were visible daily rising 200-500 m above the summit and drifting in multiple directions. Each day the seismic network recorded 213-323 rockfalls and 6-32 volcanic earthquakes. The earthquake counts included 1-6 periods of volcanic tremor, each lasting between 1-36 minutes on most days; no periods of tremor were detected on 22 June. Daily measurements of sulfur dioxide emissions averaged 1,082-3,157 tonnes per day. One PDC per day was detected on 19 and 21 June. The lava flows did not advance in the Mi-isi (S), Basud (E), and Bonga (SE) drainages, remaining 1.8, 3.8, and 3.2 km long, respectively.

The number of evacuees was similar to the previous week; by 1800 on 19 June a total of 3,977 people (1,088 families) were staying in 12 evacuation shelters, and an additional 137 people (40 families) were staying with friends or relatives, according to the Disaster Response Operations Monitoring and Information Center (DROMIC). The Alert Level remained at 3 (on a 0-5 scale) and residents were reminded to stay away from the 6-km-radius Permanent Danger Zone (PDZ). PHIVOLCS recommended that civil aviation authorities advise pilots to avoid flying close to the summit.

Geological summary: Symmetrical Mayon, which rises above the Albay Gulf NW of Legazpi City, is the most active volcano of the Philippines. The steep upper slopes are capped by a small summit crater. Recorded eruptions since 1616 CE range from Strombolian to basaltic Plinian, with cyclical activity beginning with basaltic eruptions, followed by longer periods of andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic density currents and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often damaged populated lowland areas. A violent eruption in 1814 killed more than 1,200 people and devastated several towns.

Merapi, Indonesia

7.54°S, 110.446°E; Elev. 2,910 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Merapi (on Java) continued during 18-24 June with occasional lava avalanches produced by the active lava dome on the upper SW flank. White plumes rose as high as 425 m above the summit on most days. There were 4-9 daily lava avalanches that traveled as far as 2 km down the Sat/Putih or Krasak drainages on the W flank during 18-22 and 24 June. On 23 June one pyroclastic flow was seismically detected and 29 lava avalanches descended the Sat/Putih, Krasak, and Bebeng (SW flank) drainages as far as 2 km. 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.

Geological summary: Merapi, one of Indonesia’s most active volcanoes, lies in one of the world’s most densely populated areas and dominates the landscape immediately north of the major city of Yogyakarta. It is the youngest and southernmost of a volcanic chain extending NNW to Ungaran volcano. Growth of Old Merapi during the Pleistocene ended with major edifice collapse perhaps about 2,000 years ago, leaving a large arcuate scarp cutting the eroded older Batulawang volcano. Subsequent growth of the steep-sided Young Merapi edifice, its upper part unvegetated due to frequent activity, began SW of the earlier collapse scarp. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated lands on the western-to-southern flanks and caused many fatalities.

Nyamulagira, DR Congo

1.408°S, 29.2°E; Elev. 3,058 m

The eruption at Nyamulagira continued in June based on satellite data. Incandescence on the floor of the summit caldera was visible in partly cloudy satellite images from 20 and 22 June. Lava flows on the flanks did not appear to be active, though weather clouds obscured parts of the flanks and part of the summit crater in both images.

Geological summary: Africa’s most active volcano, Nyamulagira (also known as Nyamuragira), is a massive high-potassium basaltic shield about 25 km N of Lake Kivu and 13 km NNW of the steep-sided Nyiragongo volcano. The summit is truncated by a small 2 x 2.3 km caldera that has walls up to about 100 m high. Documented eruptions have occurred within the summit caldera, as well as from the numerous flank fissures and cinder cones. A lava lake in the summit crater, active since at least 1921, drained in 1938, at the time of a major flank eruption. Recent lava flows extend down the flanks more than 30 km from the summit as far as Lake Kivu; extensive lava flows from this volcano have covered 1,500 km2 of the western branch of the East African Rift.

Poas, Costa Rica

10.2°N, 84.233°W; Elev. 2,697 m

The Observatorio Vulcanológico y Sismológico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported that a short eruption at Poás was recorded in seismic and infrasound data on 20 June. The crater area was not visible due to weather conditions. The event was followed by several pulses of seismic and acoustic tremor, possibly associated with very small eruptions. The Volcanic Alert Level remained at 2 (the second lowest level on a four-level scale).

Geological summary: The broad vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the complex stratovolcano extends to the lower N flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, last erupted about 7,500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world’s most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since an eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water.

Popocatepetl, Mexico

19.023°N, 98.622°W; Elev. 5,393 m

The Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity was low at Popocatépetl during 17-24 June. The seismic network recorded 17-342 long-period events per day, accompanied by steam-and-gas emissions that drifted NW, WNW, and WSW. According to the Washington Volcanic Ash Advisory Center (VAAC) ash plumes visible in webcam and/or satellite images on 19, 21, and 23 June rose 5.8-6.4 km (19,000-21,000 ft) a.s.l. (just over 1 km above the summit) and drifted NW and W. CENAPRED noted that during 23-24 June the seismic network recorded 53 minutes of low-amplitude, high-frequency tremor, as well as 202 minutes of sequences indicating emissions. During some of the episodes, incandescent material was ejected short distances from the crater. 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.

Geological summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, rises 70 km SE of Mexico City to form North America’s 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major Plinian eruptions, the most recent of which took place about 800 CE, have occurred since the mid-Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since Pre-Columbian time.

Purace, Colombia

2.3095°N, 76.3948°W; Elev. 4,650 m

The Servicio Geologico Colombiano (SGC) reported ongoing low-level eruptive activity at Puracé during 16-22 June. Seismic activity associated with rock fracturing processes were mainly located between Piocollo and Puracé volcanoes at depths of 1-3 km with magnitudes below 1. A thermal anomaly continued to be detected in satellite images within the crater of Puracé and in the fumarolic field along its outer rim. Sulfur dioxide emissions persisted. Slow deformation continued between Puracé, Piocollo, and Curiquinga volcanoes. Signals associated with fluid movement and emissions continued to increase. The signals were located beneath Puracé at depths less than 3 km. Gas-and-ash emissions were less frequent than the previous week. The plumes rose as high as 2 km above the summit and drifted NW. The Alert Level remained at Yellow (the second lowest level on a four-color scale).

Geological summary: Puracé is an active andesitic volcano with a 600-m-diameter summit crater at the NW end of the Los Coconucos Volcanic Chain. This volcanic complex includes nine composite and five monogenetic volcanoes, extending from the Puracé crater more than 6 km SE to the summit of Pan de Azúcar stratovolcano. The dacitic massif which the complex is built on extends about 13 km NW-SE and 10 km NE-SW. Frequent small to moderate explosive eruptions reported since 1816 CE have modified the morphology of the summit crater, with the largest eruptions in 1849, 1869, and 1885.

Reventador, Ecuador

0.077°S, 77.656°W; Elev. 3,562 m

The Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that eruptive activity at Reventador continued at a high level during 17-24 June. Seismicity included 17-88 daily explosions, long-period earthquakes, harmonic tremor, and tremor associated with emissions. Daily ash-and-gas plumes, sometimes multiple per day, were visible in webcam and satellite images and reported by the Washington Volcanic Ash Advisory Center (VAAC). The ash plumes rose 300-1,200 m above the crater rim and drifted mainly NW, W, and SW. Incandescent blocks were also visible during dark hours rolling as far as 1.1 km down the flanks on most days. Thermal anomalies were often identified in satellite images. Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at Orange (the second highest level on a four-color scale).

Geological summary: Volcán El Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic stratovolcano has 4-km-wide avalanche scarp open to the E formed by edifice collapse. A young, unvegetated, cone rises from the amphitheater floor to a height comparable to the rim. It has been the source of numerous lava flows as well as explosive eruptions visible from Quito, about 90 km ESE. Frequent lahars in this region of heavy rainfall have left extensive deposits on the scarp slope. The largest recorded eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

Sabancaya, Peru

15.787°S, 71.857°W; Elev. 5,960 m

The Instituto Geofísico del Perú’s (IGP) Centro Vulcanológico Nacional (CENVUL) reported continuing eruptive activity at Sabancaya during 15-21 June. The seismic network detected 72 seismic events related to the movement of magmatic fluids and additional earthquakes indicating rock fracturing. Gas, steam, and ash plumes periodically rose as high as 2.1 km above the crater rim and drifted less than 10 km in multiple directions. Thermal anomalies on the crater floor were identified in satellite images and moderate sulfur dioxide emissions averaged 619 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 from the summit.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning “tongue of fire” in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of observed eruptions date back to 1750 CE.

Sangay, Ecuador

2.005°S, 78.341°W; Elev. 5,286 m

The Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that the eruption continued at Sangay during 17-24 June. The seismic network recorded 104 explosions during 17-18 June; seismic data was not available during the rest of the week due to transmission problems. Ash-and-gas plumes were visible in satellite images and reported by the Washington Volcanic Ash Advisory Center to be rising 700-1,500 m above the crater rim and drifting NW on 18 June. Weather conditions often obscured views, though no emissions were visible during some clear conditions especially at the end of the week. The Secretaría de Gestión de Riesgos (SGR) maintained the Alert Level at Yellow (the second lowest level on a four-color scale).

Geological summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador’s volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within the open calderas of two previous edifices which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been eroded by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an eruption was in 1628. Almost continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Santa Maria, Guatemala

14.757°N, 91.552°W; Elev. 3,745 m

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 17-24 June, with continuing lava extrusion at Caliente dome. Incandescence at the summit was observed during dark hours, accompanying the collapse of incandescent material that descended the flanks. Effusion of blocky lava and collapses of material produced daily incandescent block avalanches that descended the flanks, mainly to the W, SW, and S; on a few of the days these collapses reportedly occurred at a rate of 1-3 per hour. Daily explosions, 1-3 per hour when reported, generated gas-and-ash plumes that rose 700-900 m above the dome and drifted SW and W. Heavy rain caused lahars to descend the Nimá I drainage on the S flank and the El Tambor drainage on the SSW flank on 17 June. The lahars were composed of water, fine sediments, tree trunks and branches, and blocks up to 1 m in diameter.

Geological summary: Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing E towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Semeru, Indonesia

8.108°S, 112.922°E; Elev. 3,657 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru during 18-24 June, with daily eruptive events recorded by the seismic network. Daily white-to-gray or gray ash plumes rose 500-1,200 m above the summit and drifted in multiple directions. At 0721 on 19 June a pyroclastic flow descended the SE flank as far as 4.5 km. The Alert Level remained at 3 (the second highest level on a scale of 1-4) and the public was warned to stay at least 5 km away from the Jonggring Saloko Crater 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.

Geological summary: Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano.

Sheveluch, Russia

56.653°N, 161.36°E; Elev. 3,283 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported continuing eruptive activity at the lava domes along the N crater floor of Young Sheveluch (on the SW flank of Old Sheveluch) during 18-24 June. A thermal anomaly was identified in satellite images on most or all days. Ash plumes from explosions on 17 June were identified in 18 June satellite images drifting 1,400 km NE. An explosive event that began at 1940 on 23 June generated ash plumes that rose 4 km (13,100 ft) a.s.l. and drifted 50 km SW. 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.

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka’s largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Suwanosejima, Japan

29.638°N, 129.714°E; Elev. 796 m

The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima’s Ontake Crater continued during 12-19 June. Incandescence was observed nightly in webcam images. White plumes rose as high as 800 m above the crater rim. No explosions were recorded. 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.

Geological summary: The 8-km-long island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two active summit craters. The summit is truncated by a large breached crater extending to the sea on the E flank that was formed by edifice collapse. One of Japan’s most frequently active volcanoes, it was in a state of intermittent Strombolian activity from Otake, the NE summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813-14, when thick scoria deposits covered residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Whakaari/White Island, New Zealand

37.52°S, 177.18°E; Elev. 294 m

On 23 June the GeoNet reported that no eruptive activity at Whakaari/White Island had been observed since their last bulletin which was posted on 7 April. Low-to-moderate steam-and-gas emissions persisted based on webcam and satellite images as well as an overflight the previous week. Measurements taken during the overflight showed decreased levels of both sulfur dioxide and carbon dioxide compared to the previous overflight on 23 April. Overall, activity was characterized as low. The Volcanic Alert Level remained at 2 (on a scale of 0-5) and the Aviation Color Code remained at Yellow (the second lowest level on a four-color scale).

Geological summary: The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari (“The Dramatic Volcano”) and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.

References:

¹ Smithsonian Institution / US Geological Survey Weekly Volcanic Activity Report – GVP – June 18-24, 2026 – Managing Editor: Sally Sennert

Teo Blašković

I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.

Earth

Space

Space weather

Monitoring tools

watchers.LIVE

SWX

SAM

StormWall

Support, updates, and contact

Subscribe

Newsletter

Report an event

Feeds and contact