The Weekly Volcanic Activity Report: July 23-29, 2026

New activity/unrest: Etna, Italy | Krakatau, Indonesia | Rincon de la Vieja, Costa Rica | Telica, Nicaragua | Tokachidake, Japan | Ulawun, Papua New Guinea.

Ongoing activity: Aira, Japan | Ambae, Vanuatu | Bulusan, Philippines | Fuego, Guatemala | Great Sitkin, United States | Ibu, Indonesia | Katmai, United States | Kilauea, United States | Kuchinoerabujima, Japan | Langila, Papua New Guinea | Lewotobi, Indonesia | Lewotolok, Indonesia | Mayon, Philippines | Merapi, Indonesia | Purace, Colombia | Sabancaya, Peru | Santa Maria, Guatemala | Semeru, Indonesia | Sheveluch, Russia | Stromboli, Italy.

New activity/unrest

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 20-26 July characterized by sporadic explosive activity and ash emissions at Northeast Crater (NEC) and Bocca Nuova Crater (BN) and gas emissions at Southeast Crater and Voragine Crater (VOR). An explosion at the W pit crater at BN produced a diffuse brown-to-gray ash plume that rapidly dissipated on 21 July. The Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile.

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.

Krakatau, Indonesia

6.1009°S, 105.4233°E; Elev. 285 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported ongoing eruptive activity at Krakatau during 23-29 July. A white, gray, and black ash plume rose as high as 300 m above the summit on 25 July and a white-and-gray ash plume rose 100 m above the summit on 26 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 summit.

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.

Rincon de la Vieja, Costa Rica

10.8314°N, 85.3364°W; Elev. 1,729 m

The Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported increased activity at Rincón de la Vieja. Starting on 1 June the seismic network detected a slight increase in background tremor, followed by volcano-tectonic earthquakes in areas both proximal and distal to the crater. A small swarm of long-period earthquakes on 28 June was coincident with a general decrease in tremor amplitude. Sulfur dioxide emissions began to gradually increase in mid-June, with averages above baseline levels; emissions averaged 460 tonnes per day (t/d) during 11-17 July and 306 t/d during 18-24 July. The geodetic network detected extension between the summit and N flank, and to a lesser extent at the base of the volcano, though there was no significant uplift. A phreatic eruption on 2 July was the first to be recorded in about six weeks. Notably, there were 38 phreatic eruptions during 2-24 July, three of which generated lahars on the N flank; the largest lahar in 2026 was recorded at 0302 on 20 July. At 0438 on 24 July a phreatic eruption that lasted around two minutes ejected ballistics 200 m above the lake’s surface and generated a gas-and-steam plume that rose 400 m and drifted W. At 0600 the Alert Level was raised to 3, Caution, (the second highest level on a four-level scale) and the Aviation Color Code was raised to Orange (the second highest level on a four-color scale).

Geological summary: Rincón de la Vieja is a volcanic complex in the Guanacaste Range of NW Costa Rica. Sometimes referred to as the Rincon de la Vieja-Santa María Volcanic Complex, it consists of a slightly arcuate 20-km-long ridge of 12 craters and pyroclastic cones constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the “Colossus of Guanacaste,” it has an estimated volume of 130 km3 and contains at least nine major eruptive centers. The Santa María cone, the highest peak of the complex, is located on the E side of the ridge and has a lake within the 400-m-diameter crater. A Plinian eruption producing the 0.25 km3 Río Blanca tephra about 3,500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous reported eruptions possibly dating back to the 16th century, have been from the active crater, near the center of the complex, with an acidic 300-m-diameter lake.

Telica, Nicaragua

12.606°N, 86.84°W; Elev. 1,036 m

According to news sources an explosion at Telica at 1230 on 24 July produced an ash plume that rose 150 m above the summit and drifted SW. The Washington Volcanic Ash Advisory Center (VAAC) reported that ash plumes visible in satellite and webcam images rose as high as 2 km (6,500 ft) a.s.l. and drifted less than 30 km W and SW during 27-28 July.

Geological summary: Telica, one of Nicaragua’s most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby.

Tokachidake, Japan

43.418°N, 142.686°E; Elev. 2,077 m

The Japan Meteorological Agency (JMA) reported that at around 1107 on 22 July a small eruption at Tokachidake’s Crater 62-2 generated a black plume that rose 200 m above the crater rim. An infrasound signal associated with the eruption had a maximum amplitude of 0.76 pascals and volcanic tremor was recorded for about 45 seconds. The Alert Level remained at 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.

Ulawun, Papua New Guinea

5.05°S, 151.33°E; Elev. 2,334 m

The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume at Ulawun had risen 3.7 km (12,000 ft) a.s.l. and drifted E by 1420 on 23 July based on satellite images and information from the Rabaul Volcano Observatory (RVO). The plume had dissipated by 2000.

Geological summary: The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea’s most frequently active. The volcano, also known as the Father, rises above the N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1,000 m is unvegetated. A prominent E-W escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and E flanks. A steep-walled valley cuts the NW side, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.

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 20-27 July. The monitoring networks recorded a total of 21 eruptive events, with no ejected ballistics nor incandescence observed. The tallest plume rose 3 km above the crater rim at 1414 on 21 July and drifted SE. The other ash plumes rose 1-1.9 km above the crater. Ash emissions were continuous for about two hours, during 1834-2045, on 25 July. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of both the Minimadake and Showa craters.

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 plumes at Ambae were identified in satellite images on 25, 27, and 29 July rising 2.4-4.6 km (8,000-15,000 ft) a.s.l. and drifting N, E, SE, and S. 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 28 July advisory, noting that a total of 109 volcanic earthquakes were recorded by the seismic network during 0000-1500. The seismicity mostly consisted of volcano-tectonic earthquakes associated with rock fracturing located at shallow depths beneath the edifice. Weak-to-moderate gas emissions rose from the summit crater and active vents; sulfur dioxide emissions were low levels, averaging 50 tonnes per day on 21 July. 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.

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 22-29 July. Daily Strombolian explosions recorded by the seismic network, at rates of 5-11 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 SW, W, and NW. Rumbling sounds, shock waves, and/or sounds associated with explosions were reported daily. Explosions occasionally ejected incandescent material as high as 300 m above the summit and onto the flanks, causing incandescent block avalanches to descend the flanks; notably avalanches descended the Seca (W), Taniluyá (SSW), Ceniza (SSW), Trinidad (SSW), Las Lajas (SE), and Honda drainages, sometimes reaching vegetated areas.

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 22-29 July. Minor earthquakes were detected daily. Weather clouds obscured views during most of the week. Elevated surface temperatures were identified in satellite images during 25-29 July. No activity was visible in clear satellite and webcam views during 26-27 July. 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 23-29 July, with daily eruptive events recorded by the seismic network. Daily gray or white-to-gray ash plumes rose 200-700 m above the summit and drifted NE, N, and NW. 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.

Katmai, United States

58.279°N, 154.9533°W; Elev. 2,047 m

The Alaska Volcano Observatory (AVO) reported that on 24 July strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the SE. The ash was originally deposited during the Novarupta-Katmai eruption in 1912. 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 level on a four-color scale).

Geological summary: Katmai was initially considered to be the source of the Valley of Ten Thousand Smokes ash flow in 1912. However, the 3 x 4 km caldera of 1912 is now known to have formed as a result of the voluminous eruption at nearby Novarupta volcano. The edifice had four NE-SW-trending summits, most of which were truncated by the 1912 collapse. Two or more large explosive eruptions took place during the late Pleistocene. Most of the two overlapping pre-1912 Katmai volcanoes are Pleistocene, but Holocene lava flows from a flank vent descend the SE flank of the SW edifice into the Katmai River canyon. The steep walled young caldera has a jagged rim that rises 500-1,000 m above the caldera floor and contains a deep lake. Lake waters have covered a small post-collapse lava dome (Horseshoe Island) that was seen on the caldera floor at the time of the initial ascent to the caldera rim in 1916.

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 22-29 July. Flaming at the S vent was visible during 22-23 July, and variable intensities of incandescence persisted at both the S and N vents during 22-27 July.

Occasional spattering at both vents occurred overnight during 27-28 July. Lava overflowed the N vent at 1022 on 28 July and was followed by five more overflows by 1353, with the longest overflow lasting 30 minutes. 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 1048. The last overflow was followed by dome fountains at the N vent rising 3-10 m and a vigorous overflow at 1356. The dome fountain grew taller and became more voluminous, transitioning to a 30-m-high lava fountain at 1910; maximum height was 150 m at 2100. The lava fountain produced significant heat and ash, feeding an eruption plume that rose as high as 5.6 km (19,000 ft) a.s.l. and drifted S based on radar data. Fine ash was observed within public areas of Hawai’i Volcanoes National Park. The plume was shorter by 2136, rising as high as 4.9 km (16,000 ft) a.s.l. Later in the evening lower winds subsided and the plume became more vertical but did not spread over populated areas. The plume gradually decreased in height to 120 m and the eruption plume decreased to 3 km (10,000 ft) a.s.l. by 2300. The episode ended at 0236 on 29 July, after around 7.4 hours of continuous fountaining from the N vent. The last four minutes were marked by gas jetting at the same vent. The average effusion rate was 190 cubic meters per second; the highest peak was 270 cubic meters per second, occurring at around 2115. An estimated 4.7 million cubic meters of lava erupted and covered 40-50 percent of the Halema’uma’u Crater floor. The S vent did not produce a fountain, but instead emitted flames. At 0301 the Volcano Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow.

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.

Kuchinoerabujima, Japan

30.443°N, 130.217°E; Elev. 657 m

The Japan Meteorological Agency (JMA) reported that the number of shallow volcanic earthquakes increased beneath an area near Kuchinoerabujima’s Furudake Crater with 100 earthquakes recorded during 18-27 July. Some of the events were located near Shindake Crater (just N of Furudake). No significant changes to emissions at either Shindake or Furudake craters were observed during a field survey on 23 July. However, the geothermal area around Shindake persisted and some areas on the Furudake Crater floor had expanded. The Alert Level was raised to 2 (on a scale of 1-5) at 2000 on 27 July; the public was warned that ejected blocks may land within 1 km of both craters, and pyroclastic flows may affect areas within 2 km of the W flank of Shindake Crater.

Geological summary: A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km W of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. All historical eruptions have occurred from Shindake, although a lava flow from the S flank of Furudake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shindake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Langila, Papua New Guinea

5.525°S, 148.42°E; Elev. 1,330 m

The Darwin Volcanic Ash Advisory Centre (VAAC) reported that ash plumes from Langila rose to 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE and N during 21 and 24-25 July based on satellite images. A thermal anomaly at the summit was identified in a 26 July image.

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 23-29 July. Multiple daily gray ash plumes rose 200-1,600 m above the summit and drifted in various directions. Minor incandescence at the summit was visible in a webcam image at 1855 on 26 July and at 0302 on 27 July. 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 23-29 July. Daily white plumes rose as high as 100 m above the summit. A dense gray ash plume from an eruptive event at 0721 on 23 July rose around 200 m above the summit and drifted E. An eruptive event at 1307 on 29 July produced a dense gray ash plume that rose around 600 m above the summit and drifted SE. Incandescent material was ejected above the summit and onto the flanks during 23-24 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 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 22-29 July, characterized by lava effusion, periodic pyroclastic density currents (PDCs), incandescent rockfalls, and occasional Strombolian activity. Emissions were visible daily, rising as high as 750 m above the summit and drifting in multiple directions. Each day the seismic network recorded 10-19 rockfalls and 1-7 volcanic earthquakes. There were also 2-3 daily PDCs during 25 and 27-28 July. Sulfur dioxide emissions averaged 1,195-2,903 tonnes per day. The lava flows did not advance in the Bonga (SE) and Basud (E) drainages, remaining 3.2, and 3.8 km long, respectively, but did advance to 2.7 km long in the Mi-isi (S) drainage by 23 July. Strombolian activity was visible on 26 July. 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 23-29 July with daily lava avalanches produced by the active lava dome on the upper SW flank. There were 4-10 daily lava avalanches that traveled as far as 2 km down the Sat/Putih or Krasak drainages on the W flank during 24-26 and 28-29 July. One pyroclastic flow traveled 2 km down the Boyong drainage (S flank) on 28 July. 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 intensifying eruptive activity at Puracé during 21-27 July. Seismic activity associated with rock fracturing processes continued at similar levels compared to the previous week, with a slight increase in intensity. The signals, with magnitudes below 1.4, were mainly located between Piocollo and Puracé volcanoes at depths of 1-3 km. Satellite images showed a persistent thermal anomaly within Puracé. An increase in the temperature of emissions at the fumarolic field located on the outer rim of Puracé was observed in thermal camera images. A significant increase in both sulfur dioxide and carbon dioxide emissions measured by instrumental and satellite monitoring systems reached the highest levels detected since the current eruptive episode began on 20 January 2025. Signals associated with fluid movement and emissions increased in intensity; both continuous tremor and tremor pulses intensified. The signals were located mainly beneath Puracé at depths less than 3 km. There was an increase in the number of daily gas-and-ash emissions and the heights of the plumes, with the tallest plume rising 3.5 km above the crater rim. Ashfall, volcanic activity noises, and ground vibrations were reported in various areas around Puracé and Coconuco, and ash also fell in Paletará (16 km SW) and Popayán (28 km 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 20-26 July. The seismic network detected 53 seismic events related to the movement of magmatic fluids, along with 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 SE. Thermal anomalies on the crater floor were identified in satellite images and moderate sulfur dioxide emissions averaged 888 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.

Santa Maria, Guatemala

14.757°N, 91.552°W; Elev. 3,745 m

The Instituto Nacional de Sismología, Vulcanología, Meteorología e Hidrología (INSIVUMEH) reported ongoing eruptive activity at Santa Maria’s Santiaguito dome complex during 22-29 July, with continuing lava extrusion at Caliente dome. Incandescence at the summit was observed during dark hours. 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 1-4 per hour. Daily explosions, 0-3 per hour when reported, generated gas-and-ash plumes that rose 800-900 m above the dome and drifted SW and W. Minor ashfall was reported in Monte Claro (S) and surrounding areas during 24-25 July and in Monte Claro, Finca Monte Bello (6 km WSW), and surrounding areas during 27-28 July.

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 23-29 July, with daily eruptive events recorded by the seismic network. White-to-gray ash plumes rose 500-800 m above the summit and drifted multiple directions on most days; emissions were not visible on 23 and 29 July. The Alert Level remained at 3 (the second lowest level on a scale of 1-4) and the public was warned to stay at least 5 km away from the 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 lava effusion and explosive activity at the lava domes along the N crater floor of Young Sheveluch (on the SW flank of Old Sheveluch) during 21-29 July. A thermal anomaly was identified in satellite images on all or most days. Explosions on 21 July produced ash plumes that rose to 9 km (29,500 ft) a.s.l. and drifted NE by 2045. The Aviation Color Code was raised to Red (the highest level on a four-color scale) at 2230 but since explosions stopped it was moved back to Orange at 0103 on 22 July. The ash plume drifted as far as 560 km NE. At 2125 on 22 July explosions generated ash plumes that rose 4 km (13,100 ft) a.s.l. and drifted 90 km ESE. Explosions during 23-24 and 26 July produced ash plumes that rose 7-8.5 km (23,000-27,900 ft) a.s.l. and drifted as far as 370 km SW and 806 km NE. The ash cloud generated by explosions on 24 July was about 2,030 km long and as wide as 180 km by 25 July, which extended over the Sea of Okhotsk with the farthest edge of the plume about 1,630 km from Sheveluch. Explosions at 1655 on 28 July generated ash plumes that rose as high as 9.6 km (31,500 ft) a.s.l. and drifted 650 km SW. 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.

Stromboli, Italy

38.789°N, 15.213°E; Elev. 924 m

The Sezione di Catania – Osservatorio Etneo (INGV) reported that eruptive activity continued at Stromboli during 20-26 July. Webcam images showed Strombolian activity from vents in Area N within the upper part of the Sciara del Fuoco, and vents in Area C-S (South-Central Crater) on the crater terrace. The vents in Area N produced high-intensity explosions that ejected lapilli and bombs above the vents. Explosions at vents in Area C-S were low-to-moderate in intensity and frequency, which ejected both fine and coarse tephra above the vents. The Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile.

Geological summary: Spectacular incandescent nighttime explosions at Stromboli have long attracted visitors to the “Lighthouse of the Mediterranean” in the NE Aeolian Islands. This volcano has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent scarp that formed about 5,000 years ago due to a series of slope failures which extends to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium.

References:

¹ Smithsonian Institution / US Geological Survey Weekly Volcanic Activity Report – GVP – July 23-29, 2026 – Managing Editor: Sally Sennert