The Weekly Volcanic Activity Report: June 25-July 1, 2026

New activity/unrest: Atka Volcanic Complex, United States | Etna, Italy | Heard, Australia | Krakatau, Indonesia | Nevados de Chillan, Chile.

New activity/unrest

Atka Volcanic Complex, United States

52.331°N, 174.139°W; Elev. 1,518 m

The Alaska Volcano Observatory (AVO) reported that a small explosion originating at Korovin’s summit crater lake within the Atka volcanic complex was detected in seismic and infrasound data at 0559 on 24 June. AVO noted that brief explosive events at Korovin were not uncommon and may occur without precursory unrest. 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).

Geological summary: The Atka Volcanic Complex consists of a central shield and Pleistocene caldera and four notable volcanic cones. A major explosive dacitic eruption accompanied formation of the caldera about 500,000 to 300,000 years ago; approximately half of the caldera rim remains, open towards the NW. The Sarichef cone, ~5 km ESE of the caldera rim, retains a symmetrical profile, unlike most other heavily eroded features outside the caldera to the S and W. The Kliuchef stratovolcano grew within the caldera and exhibits five eruptive vents striking NE, including two at the summit, that have been active in the Holocene. A 700-m-diameter crater 1 km NE of the summit may have been the source vent for a large 1812 CE eruption. Hot springs and fumaroles are located on the flanks of Kliuchef and in a glacial valley to the SW. The most frequently active volcano of the complex is Korovin, at the NE tip of Atka Island about 5 km N of Kliuchef. An 800-m-diameter crater on the SE side of the summit contains a deep circular pit that sometimes contains a crater lake thought to be the source of phreatic ash explosions. The smaller Konia cone, slightly offset to the E, lies between Kliuchef and Korovin. Most of the lava flows in the complex are basaltic, though some dacitic flows are also present.

Etna, Italy

37.748°N, 14.999°E; Elev. 3,357 m

The Sezione di Catania – Osservatorio Etneo (INGV) reported eruptive activity at Etna’s summit craters during May-June. Intra-crater explosive activity at the Northeast Crater (NEC) began in late May and continued through June. The activity was characterized by intense, continuous degassing, nighttime incandescence from the crater, and the occasional ejection of incandescent material that fell back into the crater. Bocca Nuova Crater produced episodic, diffuse ash emissions that rapidly dispersed during 14-15 June.

Activity at Voragine Crater (VOR) was notable in June. A minor collapse of a pit crater on the upper E flank of VOR occurred on 9 June. Sporadic brownish-gray ash emissions began rising from the pit crater during the morning of 10 June. INGV staff conducted a field survey on 21 June and used a drone to inspect the crater. They observed that a fracture system that had formed on the E flank between August 2025 and January 2026 had propagated to the NE and SE. Based on the survey they determined that an area on the E flank, about ~82,250 square meters in size, had moved about 3 m downslope to the SE. They also noted new fracture zones and pit craters. By the morning of 26 June the NE part of the fracture system had further extended downslope in an area near cones that had formed in 2014. At around noon that same day INGV staff observed a lava flow effusing from the terminal part of the fracture, located at about 3,030 m elevation, in the upper sector of Valle del Leone (upper Valle del Bove), and descending around 30 m. The Dipartimento della Protezione Civile raised the Alert Level to Yellow (the second lowest level on a four-level scale) at 1930. Overnight during 26-27 June weak, irregular Strombolian activity occurred at the pit crater on the upper E flank of VOR. A field survey was conducted on 27 June and drone video showed that effusion at the vent was continuing; the lava flow was around 650 m long with the distal end having advanced to around 2,780 m elevation. Intense gas emissions rose from VOR. During a field inspection two days later, on 29 June, INGV staff reported that the terminus of the lava flow had reached an area between 2,750 and 2,700 m elevation. Webcams began recording intermittent Strombolian activity of varying intensity at the pit crater later that day at around 2150.

Geological summary: Mount Etna, towering above Catania on the island of Sicily, has one of the world’s longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Heard, Australia

53.106°S, 73.513°E | Summit elev. 2745 m

According to the Toulouse Volcanic Ash Advisory Center (VAAC) an eruption at Heard was detected in satellite data at 0000 on 24 June and had ended by 0805 on 25 June. The Darwin VAAC reported that at 0600 on 24 June an ash plume was identified in a satellite image rising to 11 km (36,000 ft) a.s.l. and drifting NE. The plume was continuously emitted for a few hours, decreasing in altitude to 9.8 km (32,000 ft) a.s.l. by 0620 and to 9.1 km (30,000 ft) a.s.l. by 0920. The ash plume had detached from the volcano by 1020. At 1120 a new ash plume was identified in a satellite image rising to 9.1 km a.s.l. and drifting NE. The first plume continued to drift NE. The second plume was continuously emitted for most of the day. By 2100 the first plume has dissipated and was no longer identifiable in satellite data and the second plume had risen to 11 km a.s.l. and was drifting E. Satellite images at 0000 and 0600 on 25 June showed possible ash plumes rising to 11 km and drifting E, but by 0730 all ash had dissipated.

Geological summary: Heard Island on the Kerguelen Plateau in the southern Indian Ocean consists primarily of the emergent portion of two volcanic structures. The large glacier-covered composite basaltic-to-trachytic cone of Big Ben comprises most of the island, and the smaller Mt. Dixon lies at the NW tip of the island across a narrow isthmus. Little is known about the structure of Big Ben because of its extensive ice cover. The active Mawson Peak forms the island’s high point and lies within a 5-6 km wide caldera breached to the SW side of Big Ben. Small satellitic scoria cones are mostly located on the northern coast. Several subglacial eruptions have been reported at this isolated volcano, but observations are infrequent and additional activity may have occurred.

Krakatau, Indonesia

6.1009°S, 105.4233°E; Elev. 285 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that seismicity indicating emissions at Krakatau intensified on 26 June. A gray plume with minor ash content drifted WNW. According to the Darwin Volcanic Ash Advisory Centre (VAAC) analysis of satellite images the ash plume was continuous during 1200-1520 on 26 June, rose as high as 1.5 km (5,000 ft) a.s.l., and drifted WSW. A diffuse ash plume was visible in a satellite image at 1300 on 27 June rising to 1.5 km a.s.l. and drifting W. According to PVMBG white, gray, and black or brown-and-black plumes rose 200 m and drifted in various directions during 27 June-1 July. 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.

Nevados de Chillan, Chile

36.868°S, 71.378°W; Elev. 3,180 m

The Servicio Nacional de Geología y Minería (SERNAGEOMIN) reported that at 1100 on 26 June an ash plume at Nevados de Chillán rose around 380 m above the crater rim and drifted SE. The Alert Level remained at Yellow (the second lowest level on a four-color scale) and the Sistema y Servicio Nacional de Prevención y Repuesta Ante Desastres (SENAPRED) maintained an “Early Preventive Alert” for Pinto and Coihueco. The Servicio Geológico Minero Argentino (SEGEMAR) also maintained an Alert Level to Yellow (the second lowest level on a four-color scale).

Geological summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The dominantly andesitic Cerro Blanco (Volcán Nevado) stratovolcano is located at the NW end of the massif. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The Volcán Nuevo lava-dome complex formed during 1906-1945 on the NW flank of Viejo. The Volcán Arrau dome complex was then constructed on the SE side of Volcán Nuevo between 1973 and 1986, and eventually exceeded its height. Smaller domes or cones are present in the 5-km valley between the two major edifices.

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 22-29 June. Very small eruptive events were detected on 22 and 29 June. No crater incandescence was visible during the week. 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 an ash-and-gas plume from Ambae was identified in satellite images on 28 June rising to 2.7 km (9,000 ft) a.s.l. and drifting 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.

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.

Bulusan, Philippines

12.769°N, 124.056°E; Elev. 1,535 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported increased seismicity at Bulusan in a special advisory noting that a total of 290 volcano-tectonic (VT) earthquakes were recorded by the seismic network during 0000-2130 on 27 June. The VT earthquakes were associated with rock fracturing, with 127 of the events located at shallow depths of 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 138 tonnes per day based on the most recent measurement on 26 June. The seismicity was interpreted as being due to shallow hydrothermal or tectonic processes.

Total numbers of volcanic earthquakes per day were 321 on 27 June, 163 on 28 June, and 145 on 29 June. 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.

Geological summary: Luzon’s southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. It lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded since the mid-19th century.

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 25 June-1 July. White-to-gray ash plumes rose 500-800 m above the summit and drifted SW, NW, and E. 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.

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 25 June-1 July. Seismicity was low and small rockfalls were occasionally detected. Webcam images were often obscured by weather clouds, though steaming at the summit area was visible during 24-25 June. Slightly elevated surface temperatures were visible in satellite images during 27-28 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 25 June-1 July, 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 some 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 24 June-1 July. The seismic network recorded 4-35 daily volcanic earthquakes. Sulfur dioxide emissions ranged from 944 to 3,762 tonnes per day. Volcanic emissions generally rose as high as 400 m above the summit and drifted NE, E, SE, and S; plumes rose as high as 2 km and drifted NE, E, ESE, and S on 26 June. Four periods of ash emissions were recorded on 1 July, each lasting 17-57 minutes long. Two of the events were recorded by webcams; at 1014 a grayish ash plume rose 700 m above the crater rim and drifted SW and during 1341-1438 grayish ash plumes rose as high as 750 m above the crater rim and drifted NNW. 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.

Kelimutu, Indonesia

8.77°S, 121.82°E | Summit elev. 1639 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported a significant increase in the lake water temperature at Kelimutu’s Crater II (Tiwu Ko’ofai Nuwamuri). The water temperature rose from 28.4 degrees Celsius (C) on 9 June, to 31.3 degrees C on 16 June, and then to 35 degrees C on 30 June. The color of the lake water changed from a bluish-green to light green. An increase in the temperature of Kolorongo Spring water was also noted. There was no significant change in seismicity nor in the height of plumes rising from the lake’s surface. The Alert Level remained at 1 (on a scale of 1-4) and the public was advised not to approach Crater I (Tiwu Ata Polo), Crater II, or Crater III (Tiwu Ata Bupu).

Geological summary: Kelimutu is a small, but well-known, Indonesian compound volcano in central Flores Island with three summit crater lakes of varying colors. The western lake, Tiwi Ata Mbupu (Lake of Old People) is commonly blue. Tiwu Nua Muri Kooh Tai (Lake of Young Men and Maidens) and Tiwu Ata Polo (Bewitched, or Enchanted Lake), which share a common crater wall, are commonly colored green and red, respectively, although lake colors periodically vary. Active upwelling, probably fed by subaqueous fumaroles, occurs at the two eastern lakes. The scenic lakes are a popular tourist destination and have been the source of minor phreatic eruptions in historical time. The summit is elongated 2 km in a WNW-ESE direction; the older cones of Kelido (3 km N) and Kelibara (2 km S).

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 24 June-1 July. During a helicopter overflight on 24 June HVO geologists observed magma roiling and spattering within the N vent; S vent views were blocked by gasses. Moderate-to-strong incandescence persisted at the S vent during 24-25 June. Large flames were observed, likely caused by the ignition of volcanic gases escaping the vent, along with intermittent sprays of fine spatter caused by gas jetting. During the morning of 25 June spatter bursts occurred at the N vent and cycles of strong gas pistoning events with jetting, intermittent spatter, and flames associated with spikes in tremor started around 0400 at the S vent. Overnight during 25-26 June both vents produced continuous strong glow and intermittent spattering. Spattering at the N vent significantly increased at 0300 on 26 June along with the intensity of cyclic gas jetting and spattering at the S vent. Spattering and gas jetting at the N vent intensified at 0850 and lava overflowed the vent for about 13 minutes. Another overflow occurred during 0925-0940. HVO raised the Volcano Alert Level to Watch (the second highest level on a four-level scale) and the Aviation Color Code to Orange (the second highest color on a four-color scale) at 1727.

Lava overflowed the N vent during 0657-0715 on 27 June. Another overflow began at 0838 and lasted over an hour, producing a lava flow that extended far onto the crater floor; lava drained back into the vent at 0941. An overflow with dome fountains began at 0946. The dome fountains increased in height and by 1010 they were 15-30 m tall. Just after 1130 there was one large fountain, peaking at 300 m tall, and producing significant heat and an ash-and-gas plume that rose 5.5 km (18,000 ft) a.s.l. Tephra fallout was mainly confined within Hawai’i Volcanoes National Park. The distal part of the plume drifted along the Southwest Rift Zone; USGS field crews found minor amounts of Peleʻs hair in the town of Pāhala (40 km SW) around 1330, and Pele’s hair was also reported by Kaʻū residents. At around the same time the fountain height had decreased to 210 m and the eruption plume was rising to 5 km (17,000 ft) a.s.l. The fountain gradually decreased 100 m by 1650 and the eruption plume rose 3 km (10,000 ft) a.s.l. Fountaining stopped abruptly at 1710, after 7 hours of continuous fountaining. The last 2-3 minutes was marked by gas jetting from the N vent. The average effusion rate was 210 cubic meters per second; the highest peak was 330 cubic meters per second, occurring during 1030-1100. An estimated 4.9 million cubic meters of lava erupted and covered about 50 percent of the Halema’uma’u Crater floor. The S vent did not produce a fountain. At 1727 the Volcano Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow. Flaming at both vents was visible during 27-29 June and variable intensities of incandescence were visible at both vents during 27 June-1 July.

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.

Krasheninnikov, Russia

54.596°N, 160.27°E; Elev. 1,816 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that lava flows at Krasheninnikov continued to effuse onto the ENE and E flanks of the Northern Cone during 24 June-1 July. A bright daily thermal anomaly was identified in satellite images. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates and times are provided in Coordinated Universal Time (UTC); events are in local time only where specified.

Geological summary: The late Pleistocene to Holocene Krasheninnikov volcano is comprised of two overlapping stratovolcanoes within a 9 x 10 km Pleistocene caldera. Young lava flows from summit and flank vents descend both into the caldera and down its outer flanks, and older flows that covered much of the SE caldera rim extended downslope at least 7 km. Tephra deposits from the caldera-forming eruption directly overlie a 39,000 years before present (BP) tephra thought to be associated with the formation of Uzon caldera (Florenskii, 1988). The intra-caldera stratovolcanoes are situated along a NE-SW-trending fissure that has also produced zones of Holocene cinder cones extending 15-20 km beyond the caldera. Construction of the southern edifice began about 11,000 years BP and lasted for about 4,500 years; it has a summit crater about 800-900 m wide. The northern edifice was constructed during a cycle of similar length that began about 6,500 years ago; it has a summit crater about 1.5 km wide, within which is low cone with an 800-m-wide crater containing another small cone. An eruptive cycle during about 600-400 years BP (1350-1550 CE) produced the Pauk lava cone in the crater of the northern cone and the Yuzhny lava flow on SW flank outside the caldera, followed by the Molodoy flow from the upper SW flank (Ponomareva, 1987; Ponomareva and Tsyurupa, 1985; Ponomareva and Braitseva, 1990).

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 25 June-1 July. Multiple daily gray ash plumes rose 300-1,500 m above the summit and drifted in multiple directions. Incandescence at the summit was occasionally visible in webcam images. 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 Perempuan.

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 25 June-1 July. Daily white plumes rose as high as 200 m above the summit. There were also daily white-and-gray or gray ash plumes that rose 300-700 m above the summit and drifted NW, W, and SE. Nighttime webcam images often 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 24 June-1 July, characterized by lava effusion, periodic pyroclastic density currents (PDCs), incandescent rockfalls, occasional ash-and-gas plumes, and occasional minor Strombolian activity. Emissions were visible daily rising 200-1,250 m above the summit and drifting W, NE, and E. Each day the seismic network recorded 173-327 rockfalls and 4-34 volcanic earthquakes. The earthquake counts included 2-16 periods of volcanic tremor, each lasting from one minute to just over one hour. Sulfur dioxide emissions averaged 1,446-3,337 tonnes per day. 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. One PDC per day was detected on 28 and 29 June, and nine occurred on 1 July.

The number of evacuees was unchanged compared to the previous week; by 1800 on 29 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 25 June-1 July with occasional lava avalanches produced by the active lava dome on the upper SW flank. White plumes rose as high as 400 m above the summit on most days. There were 5-18 daily lava avalanches that traveled as far as 2 km down the Sat/Putih or Krasak drainages on the W flank or the Boyong drainage on the S flank. On 28 June one pyroclastic flow descended the Sat/Putih drainage 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.

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 23-29 June. Seismic activity associated with rock fracturing processes continued with signals mainly located between Piocollo and Puracé volcanoes at depths of 1-3 km and 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 and slow deformation continued between Puracé, Piocollo, and Curiquinga volcanoes. Signals associated with fluid movement and emissions were ongoing from 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 1 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.

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 22-29 June. The seismic network detected 64 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 1.5 km above the crater rim and drifted less than 10 km NE, E, and SE. Thermal anomalies on the crater floor were identified in satellite images and moderate sulfur dioxide emissions averaged 659 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.

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 25 June-1 July, with daily eruptive events recorded by the seismic network. White-to-gray ash plumes rose 300-1,300 m above the summit and drifted in multiple directions on most days; emissions were not visually observed on 26 June. According to a news report one of the ash plumes, detected at 1639 on 29 June, was accompanied by an explosion and booming sound heard at the Mount Semeru Observation Post. The ash plume rose 1.2 km above the crater rim. 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.

Shishaldin, United States

54.756°N, 163.97°W | Summit elev. 2857 m

The Alaska Volcano Observatory (AVO) reported ongoing unrest at Shishaldin during 24 June-1 July. Minor seismic activity and infrasound signals were detected daily. Typical plumes of sulfur dioxide and steam rose from the crater based on satellite images. Weather clouds often obscured webcam views. 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: The symmetrical glacier-covered Shishaldin in the Aleutian Islands is the westernmost of three large stratovolcanoes in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning “mountain which points the way when I am lost.” Constructed atop an older glacially dissected edifice, it is largely basaltic in composition. Remnants of an older edifice are exposed on the W and NE sides at 1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is covered by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century. A steam plume often rises from the summit crater.

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 25 June-1 July. A daily thermal anomaly was identified in satellite images. Explosions at 1520 on 29 June generated ash plumes that rose as high as 9.5 km (31,200 ft) a.s.l. and drifted 140 km NW. 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 19-26 June. Incandescence was observed nightly in webcam images. Eruptive plumes rose as high as 400 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.

Taal, Philippines

14.0106°N, 120.9975°E; Elev. 311 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported eruptive activity at Taal during 24 June-1 July. The seismic network recorded 0-3 daily volcanic earthquakes, and a period of volcanic tremor that lasted for two minutes on 25 June. Daily gas-and-steam emissions rose as high as 1.5 km above the crater rim and drifted NE, ENE, and SE. A minor phreatomagmatic eruption during 0713-0717 on 30 June ejected dark material above the lake’s surface and produced an eruption plume that rose 450 m above the crater rim. A larger phreatomagmatic eruption occurred later that day at 1434 and lasted four and a half minutes based on seismic, infrasound, and visual observations. The event consisted of three pulses that each produced jets of dark gray ash and steam-rich plumes that rose 1.2 km above the crater rim and drifted SW. 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.

Geological summary: Taal is one of the most active volcanoes in the Philippines and has produced some powerful eruptions. The 15 x 20 km Talisay (Taal) caldera is largely filled by Lake Taal, whose 267 km2 surface lies only 3 m above sea level. The maximum depth of the lake is 160 m, with several submerged eruptive centers. The 5-km-wide Volcano Island in north-central Lake Taal is the location of all observed eruptions. The island is composed of coalescing small stratovolcanoes, tuff rings, and scoria cones. Powerful pyroclastic flows and surges have caused many fatalities.

Titan Ridge, Papua New Guinea

3.03°S, 147.78°E; Elev. -1,300 m

On 27 June the UN International Organization for Migration (IOM), Papua New Guinea, reported that communities on Manus and surrounding islands continued to be impacted by pumice rafts from Titan Ridge. Working with the National Disaster Centre, Manus Provincial Administration, and local authorities, IOM found that more than 10,000 residents dependent on fishing across seven local governments were affected. They also noted impacts to other coastal-based livelihoods, food security, sea-based transportation, and access to markets and essential services, along with a need for scientific assessments. A person located on Manus Island posted photographs taken on 28 June showing pumice rafts in a bay and waterway, noting that although ocean currents had begun to clear the pumice, blockages continued.

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.

References:

¹ Smithsonian Institution / US Geological Survey Weekly Volcanic Activity Report – GVP – June 25-July 1, 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.

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