The Weekly Volcanic Activity Report: October 8-14, 2026

New eruptive activity or unrest: Krakatau, Indonesia | Manam, Papua New Guinea | Marapi, Indonesia | Nevados de Chillan, Chile.

Continuing eruptive activity, unrest, or other observations: Aira, Japan | Bezymianny, Russia | Dukono, Indonesia | Etna, Italy | Fuego, Guatemala | Great Sitkin, United States | Ibu, Indonesia | Kanlaon, Philippines | Karangetang, Indonesia | Kilauea, United States | Lewotolok, Indonesia | Masaya, Nicaragua | Mayon, Philippines | Merapi, Indonesia | Popocatepetl, Mexico | Purace, Colombia | Sabancaya, Peru | Santa Maria, Guatemala | Semeru, Indonesia | Sheveluch, Russia | Stromboli, Italy | Suwanosejima, Japan | Taal, Philippines.

New activity/unrest

Krakatau, Indonesia

6.1009°S, 105.4233°E; Elev. 285 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported an increase in low-level eruptive activity at Krakatau starting in early October. During 21 September-9 October seismicity indicating both shallow and deep magmatic processes did not significantly increase. Minor white-to-black ash plumes were occasionally visible in webcam images rising as high as 50 m above the crater, though weather conditions sometimes prevented views. Satellite data indicated low sulfur dioxide emissions as high as 238 tons per day and low-level thermal anomalies. Five eruptive events were recorded during 6-8 October, followed by nine eruptive events just on 9 October, indicating increasing low-level activity. The Alert Level was raised to 3 (on a scale of 1-4) at 2100 on 9 October and the public was advised to stay 5 km away from 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.

Manam, Papua New Guinea

4.08°S, 145.037°E; Elev. 1,807 m

The Darwin Volcanic Ash Advisory Centre (VAAC) reported that ash plumes from Manam rose to 2.1 km (7,000 ft) a.s.l. and drifted E, NE, N, and NW during 8-9 and 11-13 October.

Geological summary: The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country’s most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island’s shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Marapi, Indonesia

0.38°S, 100.474°E; Elev. 2,885 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity at Marapi (on Sumatra) continued during 8-14 October. An eruptive event was recorded at 0002 on 13 October by the seismic network but not visually observed due to weather conditions. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the active crater.

Geological summary: Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra’s most active volcano. This massive complex stratovolcano rises 2 km above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping craters constructed within the 1.4 km Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been observed.

Nevados de Chillan, Chile

36.868°S, 71.378°W; Elev. 3,180 m

The Servicio Nacional de Geología y Minería (SERNAGEOMIN) and the Servicio Geológico Minero Argentino (SEGEMAR) reported that eruptive activity at Nevados de Chillán was ongoing in mid-October. A new lava flow was first visible at the summit of Nuevo volcano on 29 September and traveled SW. During a field visit on 1 October scientists observed the ejection of meter-sized blocks as high as 500 m above the summit and outward as far as 250 m. The blocks landed on the flanks and rolled up to 400 m from the crater rim.

During 8-14 October activity was characterized by periodic long-period earthquakes indicating fluid movement at depth, and occasional ash plumes and explosions. Weather conditions sometimes prevented views. At 1655 on 8 October an ash plume rose 860 m above the summit and drifted SE. A long-period earthquake was detected at 0330 on 12 October and was associated with the ejection of incandescent material onto the upper flanks. At 1224 on 12 October an ash plume rose 500 m and drifted SSE. A series of consecutive explosions around midday on 13 October produced ash plumes that rose as high as 600 m above the summit, with the tallest plume recorded at 1354. A long-period earthquake was detected at 1548 on 13 October along with an acoustic signal indicating explosive activity; weather conditions prevented visual confirmation. An ash plume rose 400 m at 1558 on 14 October. A few hours later, at 1957, another seismic signal indicated explosive activity. The Alert Level remained at Yellow (the second lowest level on a four-color scale) and the public was warned that an eruption may impact areas within 2 km of the active crater. The Sistema y Servicio Nacional de Prevención y Repuesta Ante Desastres (SENAPRED) maintained an “Preventive Early Alert” for Pinto and Coihueco and warned the public to stay 2 km away from Emission Center 3 (EC3).

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 5-12 October. Crater incandescence was visible in nighttime webcam images during 5-9 October. A total of 15 eruptive events during 5-8 October produced ash plumes that rose 1-1.6 km above the crater and drifted in various directions. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 1 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.

Bezymianny, Russia

55.972°N, 160.595°E; Elev. 2,882 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that effusive activity at Bezymianny continued during 8-14 October. A thermal anomaly was identified in satellite images on most days; the volcano was occasionally obscured by weather clouds. Dates and times are provided in Coordinated Universal Time (UTC); events are in local time only where specified.

Geological summary: The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

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 8-14 October, though hazy conditions prevented visual observations. Eruptive events were recorded by the seismic network during 8 and 10-12 October. Faint rumbling was heard at the Dukono observation post (11 km N) on 10 October. 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.

Etna, Italy

37.748°N, 14.999°E; Elev. 3,357 m

The Sezione di Catania – Osservatorio Etneo (INGV) reported that eruptive activity at Etna’s summit craters during 5-11 October was characterized by gas emissions at the summit craters and periodic minor ash emissions at Northeast Crater (NEC). Adverse weather conditions often prevented visual observations. The volcano 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, on the island of Sicily, has one of the world’s longest documented records of volcanism, dating back to 1500 BCE. Basaltic lava flows 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 down the flanks in all directions and have reached the sea over a broad area on the SE side.

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 6-14 October. Daily explosions recorded by the seismic network, at rates of 2-8 per hour, generated gas-and-ash plumes that rose as high as 1.1 km above the summit and mainly drifted as far as 40 km in various directions. Shock waves and rumbling sounds from explosions were reported almost daily. Explosions also often ejected incandescent material, sometimes as high as 300 m above the summit, and onto the flanks causing incandescent block avalanches; notable avalanches descended the Seca (W), Taniluyá (SSW), Ceniza (SSW), Honda, and Las Lajas (SE) drainages, sometimes reaching vegetated areas. On 7 October lahars descended the Mineral and Seca drainages, carrying tree branches, trunks, and blocks as large as 3 m in diameter. Ashfall was reported in El Porvenir (11 km SW), El Rodeo (10 km SSE), La Reina, La Reunión (7 km SE), and surrounding areas during 6-7 October, in Yepocapa (8 km NW) and nearby areas during 10-11 October, and in Panimaché II (8 km SW), Yepocapa, and surrounding areas during 13-14 October.

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 that advanced SE during 7-14 October based on webcam and satellite images. Minor earthquakes consistent with the growth of the lava dome and occasional rockfalls were detected by the seismic network. Weather clouds obscured webcam and satellite views during most of the week, though elevated surface temperatures were identified in satellite images during 7-8 October. 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 1-7 October, 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. 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 7-14 October. The seismic network recorded 0-19 daily volcanic earthquakes and during 11-13 October 5-6 daily periods of volcanic tremor lasting 2-64 minutes. In general, sulfur dioxide emissions ranged from 932 to 3,219 tonnes per day (t/d), though a peak of 4,656 t/d was recorded on 10 October, the same day as a larger eruptive event. Moderate-to-voluminous volcanic emissions generally rose as high as 1.2 km above the summit and drifted in various directions.

A moderately explosive eruption at 1246 on 10 October produced an ash plume that rose 5-6 km above the summit and drifted NNE. The event lasted for two minutes, though ash emissions were recorded for two hours and 41 minutes. The Office of Civil Defense – Negros Island Region (OCD-NIR) reported that residents of Bago City observed the ash plume, heard booming sounds, and felt the ground shake. A sulfur odor was reported in parts of barangay Codcod in San Carlos City. Ashfall and a sulfur odor were reported in barangay Ara-al, Gintubdan, and in the barangays Igmayaan, Bunga, Bacong, Kumaliskis, Bago, and Pandanon, in Don Salvador Benedicto, based also on a news report. Residents of La Carlota City heard rumbling. On 11 October a total of 10 ash emissions lasting 11 minutes to three hours and 33 minutes generated ash plumes that rose as high as 600 m above the summit and drifted NNW, NW, and W. Several of the events were visible in webcam images; at 0318 minor Strombolian activity produced an ash plume that rose 500 m above the summit and drifted WNW. At 0000 and during 0545-0724 on 12 October ash plumes rose 300 m above the crater rim and drifted NW. 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.

Karangetang, Indonesia

2.781°N, 125.407°E; Elev. 1,797 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Karangetang’s North Crater (Kawah Dua) continued during 8-14 October. White plumes rose as high as 20 m above the summit and drifted in various directions on most days. At 1402 on 11 October a white-and-gray ash plume rose 700 m above the summit and drifted W and NW. Nearly an hour later, at 1459, a white, gray, and brown ash plume rose 700 m above the summit and drifted W and NW. Faint rumbling was heard on 12 October, though no emissions were recorded. Incandescent avalanches on the flanks were visible in a 13 October webcam image. Dense white plumes rose as high as 1 km above the summit an drifted N and NW on 14 October.

A 5 October new article noted that lava flows or incandescent avalanches of material descended the flanks 700 m S, as far as 1 km SW and W, and 100-700 m NW. The Alert Level remained at 2 (on a scale of 1-4) and the public was advised to stay 1.5 km away from both craters, with an extension to 2.5 km on the NW and SW flanks of North Crater.

Geological summary: Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia’s most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented (Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.

Kilauea, United States

19.421°N, 155.287°W; Elev. 1,222 m

The Hawaiian Volcano Observatory (HVO) reported that the eruption within Kīlauea’s Kaluapele summit caldera, characterized by incandescence, intermittent spatter, and lava flows from vents along the SW and W margins of Halemaʻumʻu Crater, continued at variable levels during 7-14 October. Incandescence and flaming continued to be visible at the N and S vents during 6-11 October, with periodic spattering at the N vent. Robust volcanic gas plumes rose from both vents in daytime webcam views. Several small lava overflows from a small vent at the base of N vent were observed during 9-10 October. The small vent also intermittently spattered until 2315 on 10 October when it began continuously effusing a small, tube-fed pāhoehoe flow. Overnight during 11-12 October moderate-to-strong incandescence was visible at the N vent, at the vent near its base, and at the S vent, while incandescence from the W vent fluctuated, with visibility potentially affected by fog. Intermittent flames and minor spattering associated with gas jetting occurred at all vents, including a short period of sustained spattering at the S vent that began at around 0318 on 12 October. Spattering from the vent at the base of the N vent occurred intermittently. Visible spattering ended at around 0635. Vigorous dome fountaining began at the N vent just before 1130 on 13 October, lasted nearly an hour, and produced a lava flow that traveled about 1 km. This was the longest and most vigorous dome fountain since 30 September. Two other substantial fountain and overflow episodes occurred at 1600-1640 and at 1700-1720. Interspersed between and following these longer events were about 15 smaller events that lasted only a few minutes and produced flows less than 100 m long. Sustained fountaining was followed by gas jetting, often with sprays of spatter produced during drainbacks of lava within the vents. The Volcano Alert Level remained at Watch (the second highest level on a four-level scale) and the Aviation Color Code at Orange (the second highest color on a four-color scale).

Geological summary: Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the Island of Hawai`i. 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 Halema`uma`u 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.

Lewotolok, Indonesia

8.274°S, 123.508°E; Elev. 1,431 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported continuing eruptive activity at Lewotolok during 8-14 October. On 8 and 11 October dense gray ash plumes rose around 500 m above the summit and drifted W and NW, and white steam-and-gas plumes rose 100 m above the summit and also drifted W and NW on 9, 12, and 14 October; no emissions were recorded on 10 and 13 October. Active lava flows on the S and SE flanks were 400-600 m long. The Alert Level remained at 2 (on a scale of 1-4). The public was warned to stay 2 km away from the summit with an extension to 3 km on the S and SE flanks.

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.

Masaya, Nicaragua

11.9844°N, 86.1688°W; Elev. 594 m

The Washington Volcanic Ash Advisory Center (VAAC) reported that on 9 October ash plumes from Masaya were visible in webcam images rising to 1.2-1.5 km (4,000-5,000 ft) a.s.l. and drifting SW and W. Weather clouds blocked satellite views.

Geological summary: Masaya volcano in Nicaragua has erupted frequently since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano’s molten “gold” until it was found to be basalt rock upon cooling. It lies within the massive Pleistocene Las Sierras caldera and is itself a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The Nindirí and Masaya cones, the source of observed eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6,500 years ago. Recent lava flows cover much of the caldera floor and there is a lake at the far eastern end. A lava flow from the 1670 eruption overtopped the north caldera rim. Periods of long-term vigorous gas emission at roughly quarter-century intervals have caused health hazards and crop damage.

Mayon, Philippines

13.257°N, 123.685°E; Elev. 2,462 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported ongoing eruptive activity at Mayon during 7-14 October. The seismic network recorded 6-14 daily volcanic earthquakes. Sulfur dioxide emissions generally averaged 905-1,474 tonnes per day. Daily emissions rose 100-900 m above the crater and drifted WNW, WSW, and SW. Minor Strombolian activity at 0318 on 11 October generated an ash plume that rose 500 m above the summit and drifted WNW. The Alert Level remained at 2 (on a 0-5 scale) and the public was 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 8-14 October with avalanches produced by the active lava dome on the upper SW flank. The seismic network recorded multiple lava avalanches per day on most days that traveled as far as 2 km down the Sat/Putih, Bebeng, and Krasak drainages on the SW flank and the Boyong drainage on the S flank. 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.

Popocatepetl, Mexico

19.023°N, 98.622°W; Elev. 5,393 m

The Centro Nacional de Prevención de Desastres (CENAPRED) reported that eruptive activity was low at Popocatépetl during 7-14 October. The seismic network recorded 19-42 long-period events per day, accompanied by steam-and-gas emissions that drifted in multiple directions; the emissions contained small amounts of ash on a few of the days. The seismic network also detected one volcano-tectonic earthquake per day on 9, 11, and 13 October. According to the Washington Volcanic Ash Advisory Center (VAAC) ash plumes were visible in webcam and satellite images during 12-14 October rising 6.1-7.3 km (20,000-24,000 ft) a.s.l. (as high as 1.9 km above the summit) and drifted W and WSW. The Alert Level remained at Yellow, Phase Two (the middle level on a three-color scale) and the public was warned to stay 12 km away from the crater.

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

Purace, Colombia

2.3095°N, 76.3948°W; Elev. 4,650 m

The Washington Volcanic Ash Advisory Center (VAAC) reported that during 8-14 October daily ash plumes from Puracé rose to 5.1-6.1 km (17,000-20,000 ft) a.s.l., or as high as 1.4 km above the summit, and drifted NW, WNW, and SW based on webcam images, satellite images, weather models, and Volcano Observatory Notices to Aviation issued by the Servicio Geológico Colombiano (SGC). Emissions on 13 October were considered likely, but were not detected due to weather conditions. 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 5-11 October. The seismic network detected 18 seismic events associated with the movement of magmatic fluids, along with earthquakes indicating internal rock fracturing; no volcanic explosions occurred during the period. Gas, steam, and ash emissions periodically rose as high as 800 m above the summit and drifted less than 10 km NE and E. Moderate sulfur dioxide emissions averaged 865 tons per day, and 12 thermal anomalies (each 1 MW or less) associated with the lava dome were identified. 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 7-14 October, 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, particularly the W, SW, and S flanks; during 7-8 and 11-12 October these collapses generated short pyroclastic flows that reached the base on the cone. Daily explosions, 0-3 per hour when reported, generated gas-and-ash plumes that rose as high as 1.1 km above the dome and drifted SW and W. On 7 October lahars descended the Nimá 1 drainage on the SW flank and the Tambor drainage on the SSW flank, carrying sediment, tree trunks, branches, and volcanic blocks up to 1 m in diameter. Ashfall was reported in Santa María de Jesús (5 km SE), the villages of Belén (10 km S) and Calaguache (9 km S), and other nearby communities during 7-8 October, in La Trinidad (13 km SSE), Santa Nita, Nueva Destina, Pawilonia, Rosario, and San Marcos Palajunoj (8 km SW) areas during 12-13 October, and in the mountainous area of the Monteclaro settlement and its surroundings during 13-14 October.

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 8-14 October, with daily eruptive events recorded by the seismic network. White-to-gray or gray ash plumes rose 300-1,000 m above the summit and drifted in multiple directions on most days; emissions were not visible due to weather conditions on 8 and 10 October. The Alert Level remained at 3 (the second highest level on a scale of 1-4) and the public was warned to stay at least 5 km away from the Jonggring Saloko Crater in all directions, 13 km from the summit on the SE flank along the Kobokan drainage, and 500 m from the banks of the Kobokan drainage as far as 17 km SE of the summit.

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

Sheveluch, Russia

56.653°N, 161.36°E; Elev. 3,283 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported continuing 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 7-14 October. A thermal anomaly was identified in satellite images on a few of the days; weather clouds occasionally obscured views. 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.

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 5-11 October. 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. Explosions at Area N ejected lapilli and bombs above the vents and explosions at Area C-S ejected both fine and coarse tephra above the vents. The daily frequency of explosions at both vents was at medium level and the intensity of the explosions was generally at low levels. Lava overflowed vent N1 in Area N at 1505 on 5 October and ended at 0050 on 6 October. The lava flow descended the upper part of the Sciara del Fuoco. A second overflow occurred later that morning during approximately 0925-1040. 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.

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 during 7-8 October produced ash plumes that rose as high as 400 m above the crater rim. The activity was the first recorded since 25 July. 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 6-12 October. The seismic network recorded 0-34 daily volcanic earthquakes, including 1-9 periods of volcanic tremor each day during 7-10 October, with periods lasting between 2 and 82 minutes. Daily gas-and-steam emissions generally rose 600-1,500 m above the crater rim and drifted W, SW, and SE. Sulfur dioxide emissions averaged 952-3,071 tonnes per day during 6 and 8-10 October. A minor phreatomagmatic eruption at 1806 on 8 October generated a dark ash plume that rose 4 km above the crater rim and drifted SW. Incandescent material and lightning were visible in the plume. The event lasted for five minutes based on seismic data and webcam footage. According to a news source at least 120 people, or 32 families, evacuated to centers as of 1053 on 9 October. 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.

References:

¹ Smithsonian Institution / US Geological Survey Weekly Volcanic Activity Report – GVP – October 8-14, 2026 – Managing Editor: Sally Sennert