The Weekly Volcanic Activity Report: October 22-28, 2026

New eruptive activity or unrest: Chikurachki, Russia | Kikai, Japan | Nevados de Chillan, Chile | Piton de la Fournaise, France | Whakaari/White Island, New Zealand.

Continuing rruptive sctivity, unrest, or other observations: Ahyi, United States | Aira, Japan | Ambae, Vanuatu | Ambrym, Vanuatu | Etna, Italy | Great Sitkin, United States | Ibu, Indonesia | Karangetang, Indonesia | Kilauea, United States | Krasheninnikov, Russia | Langila, Papua New Guinea | Lewotolok, Indonesia | Manam, Papua New Guinea | Marapi, Indonesia | Mayon, Philippines | Merapi, Indonesia | Purace, Colombia | Sabancaya, Peru | Semeru, Indonesia | Sheveluch, Russia | Suwanosejima, Japan | Taal, Philippines | Yasur, Vanuatu.

New activity/unrest

Chikurachki, Russia

50.324°N, 155.461°E; Elev. 1,781 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that an explosive eruption at Chikurachki likely began at 0520 on 26 October based on satellite data and advisories issued by the Tokyo Volcanic Ash Advisory Center (VAAC). Ash plumes rose as high as 5.6 km (18,400 ft) a.s.l. and drifted 240 km E. At 1735 the Aviation Color Code was raised to Orange (the second highest level on a four-color scale). No additional explosions were recorded over the next few days. At 2226 on 28 October the Aviation Color Code was lowered to Yellow. Dates are based on UTC; specific events are in local time where noted.

Geological summary: Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is a relatively small cone constructed on a high Pleistocene edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the cone give it a distinctive red color. Frequent basaltic Plinian eruptions have occurred during the Holocene. Lava flows have reached the sea and formed capes on the NW coast; several young lava flows are also present on the E flank beneath a scoria deposit. The Tatarinov group of six volcanic centers is located immediately to the south, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. The Tatarinov centers are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of an eruption around 1690 CE from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.

Kikai, Japan

30.793°N, 130.305°E; Elev. 704 m

The Japan Meteorological Agency (JMA) reported that an eruption at Iodake Crater (at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim) was recorded at 0207 on 17 May, the first since 29 December 2025. An ash-and-gas plume rose 400 m above the crater rim and drifted S. The report noted that volcanic earthquakes remained infrequent, and no notable changes were detected before or after the eruption. No volcanic tremors were recorded. The Alert Level remained at 2 (on a 5-level scale), and residents were warned to be cautious within 500 m away from Iodake Crater.

Geological summary: Multiple eruption centers have exhibited recent activity at Kikai, a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. It was the source of one of the world’s largest Holocene eruptions about 6,300 years ago when rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake (or Iwo-dake) lava dome and Inamuradake scoria cone, as well as submarine lava domes. Recorded eruptions have occurred at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km E of Satsuma-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Satsuma-Iojima.

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 during 22-28 October. The lava flow continued to advance down the SW flank. Multiple ash plumes were recorded on 25 October. Gray-and-white ash-and-gas plumes associated with long-period earthquakes recorded at 0741, at 0827, at 0834, and at 1015 rose 900-1,500 m above the summit and drifted SE; the plume at 1015 had high ash content. At least seven gray-and-white ash-and-gas plumes rose as high as 1.8 km above the summit and drifted SE during 1144-1348. An additional six or more ash plumes were recorded during 1323-1623 and rose as high as 2.3 km above the summit and drifted mainly SE. During the early morning hours of 27 October crater incandescence was visible along with explosions that ejected incandescent material above the vent and onto the NW flank. An explosion at 0626 generated a dark gray ash plume that rose 2 km above the crater rim and drifted NW. A dark gray ash plume from an explosion an hour later, at 0726, rose 960 m above the carter rim and drifted NNE. During 0804-1200 at least eight grayish ash-and-gas plumes rose 800-1600 m above the crater rim and drifted N. At 1234 on 28 October gas-and-ash plumes rose 1.3 km above the crater rim and drifted NE. Later that afternoon ash plumes rose 2.4 km above the crater rim and drifted NW at 1732 and 2 km above the crater rim and drifted NW at 1849.

On 28 October SERNAGEOMIN announced a new Alert Level system for Chilean volcanoes consisting of a numerical scale for the Estados de Actividad Volcánica (EAV), or Volcanic Activity States, from 0-5 EAV, instead of a color-coded scheme. Nevados de Chillán was at Alert Level EAV 3. The Sistema y Servicio Nacional de Prevención y Repuesta Ante Desastres (SENAPRED) did not change their three-level color system, maintaining an “Preventive Early Alert” for Pinto and Coihueco and warning 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.

Piton de la Fournaise, France

21.244°S, 55.708°E; Elev. 2,632 m

The Observatoire Volcanologique du Piton de la Fournaise (OVPF) reported that a magmatic intrusion was detected beneath the S rim of Dolomieu Crater at Piton de la Fournaise during 1609-1703 on 24 October based on seismic data. The seismic network recorded 146 shallow volcano-tectonic earthquakes with magnitudes less than 1. The Alert Level was raised to 1 (or an Orange Alert) and public access to the caldera was restricted. During 24-26 October seismicity decreased to levels slightly lower than those observed before the intrusion. The Alert Level was lowered back to “Vigilance” (or a Yellow Alert) on 26 October and access to the upper part of the caldera was permitted.

Geological summary: Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three scarps formed at about 250,000, 65,000, and less than 5,000 years ago by progressive eastward slumping, leaving large embayments open to the E and SE. Numerous pyroclastic cones are present on the floor of the scarps and their outer flanks. Most recorded eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest scarp, which is about 9 km wide and about 13 km from the western wall to the ocean on the E. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Eruptions in 1708, 1774, 1776, 1800, 1977, and 1986 originated from fissures outside the scarps.

Whakaari/White Island, New Zealand

37.52°S, 177.18°E; Elev. 294 m

The GeoNet reported that minor eruptive activity continued at Whakaari/White Island during 21-27 October. Gas plumes with diffuse ash continued to rise from the vent and drifted downwind toward the Bay of Plenty coast to the S. Short-lived energetic plumes were occasionally visible rising 1-1.5 km a.s.l. The Volcanic Alert Level remained at 3 (on a scale of 0-5) and the Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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

Ongoing activity

Ahyi, United States

20.437°N, 145.03°E; Elev. -55 m

The US Geological Survey reported that small submarine plumes of discolored greenish water were visible in 16 and 21 October satellite images drifting several hundred meters from Ahyi Seamount. The plumes were likely associated with degassing and hydrothermal activity. No signals were detected in data from underwater pressure sensors near Wake Island (about 2,270 km E of Ahyi). The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale) and the Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale).

Geological summary: Ahyi seamount is a large conical submarine volcano ~18 km SE of the island of Farallon de Pajaros in the northern Marianas. Water discoloration has been observed there, and in 1979 the crew of a fishing boat felt shocks over the summit area, followed by upwelling of sulfur-bearing water. On 24-25 April 2001 an explosive eruption was detected seismically by a station on Rangiroa Atoll, Tuamotu Archipelago. The event was well constrained (+/- 15 km) at a location near the southern base of Ahyi. An eruption in April-May 2014 was detected by NOAA divers, hydroacoustic sensors, and seismic stations.

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 19-26 October. A total of 25 eruptive events and eight explosions produced ash plumes that rose as high as 1.8 km above the crater. Large blocks were also ejected as far as 500 m from the vent during 19-23 October. Crater incandescence was visible in nighttime webcam images throughout the week. 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.

Ambae, Vanuatu

15.389°S, 167.835°E; Elev. 1,496 m

The Vanuatu Meteorology and Geohazards Department (VMGD) reported that minor eruptive activity continued at Ambae during October. Persistent volcanic tremor and continuous volcano-seismic events were detected. Satellite imagery during September-October 2026 showed ongoing emissions from the active vents, with the plumes containing variable levels of volcanic gases, steam, and/or ash. Satellite data indicated continuous low-to-moderate thermal anomalies, and high- to very-high sulfur dioxide emissions confirmed ongoing degassing. The Alert Level remained at 3 (on a scale of 0-5), and the public was advised to stay outside Danger Zone B, defined as a 3-km radius around the active vents in Lake Voui, and to avoid streams during heavy rains due to lahar hazards from the remobilization of residual ash.

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.

Ambrym, Vanuatu

16.25°S, 168.12°E; Elev. 1,334 m

The Vanuatu Meteorology and Geohazards Department (VMGD) reported that the eruption at Ambrym’s Marum Crater that began on 19 September continued through October. Elevated seismic activity and moderate-to-high levels of sulfur dioxide emissions were ongoing. Thermal anomalies identified in satellite images were sometimes very intense and indicated active lava flows in the crater. Satellite data from 19 and 24 October suggested that both of the main vents in the lava lake remained active. Field observations on 27 October confirmed that both vents were active; one vent produced Strombolian activity while the other was characterized by high fumarolic activity. The Alert Level remained at 3 (on a scale of 0-5) and the public was warned to stay outside of Permanent Danger Zone B, defined as a 2-km radius around Benbow Crater, a 2.5-km radius around Marum Crater (including Maben-Mbwelesu, Niri-Mbwelesu, and Mbwelesu craters), and a 1.5-km radius around the 2018 fissures.

Geological summary: Ambrym is a large basaltic volcano with a 12-km-wide caldera formed during a major Plinian eruption with dacitic pyroclastic flows about 1,900 years ago. A thick, almost exclusively pyroclastic sequence, initially dacitic then basaltic, overlies lava flows of a pre-caldera shield volcano. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have been frequently reported since 1774, though mostly limited to extra-caldera eruptions that would have affected local populations. Since 1950 observations of eruptive activity from cones within the caldera or from flank vents have occurred almost yearly.

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 19-25 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.

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 21-28 October based on webcam and satellite images. Lava continued to flow into the SE lobe, but the lobe did not advance at its margin. The S flank of the dome slowly advanced and generated occasional small rockfalls. Minor earthquakes consistent with the growth of the lava dome 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 21-22 October. Diffuse steaming from the active part of the flow was visible in webcam images during 27-28 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 22-28 October, with daily eruptive events recorded by the seismic network. Daily gray ash plumes rose 300-600 m above the summit and drifted NE, N, NW, and W. Incandescence at the summit was occasionally visible in 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.

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 22-28 October. White plumes rose as high as 1 km above the summit and drifted in various directions on most days. Incandescence at the North Crater and from lava flows and/or incandescent avalanches on the flanks were visible in webcam images throughout the week. At 1241 on 26 October an ash plume rose around 700 m above the summit and drifted W. An ash plume rose around 800 m above the summit and drifted NW at 0543 on 27 October and later that day, at 1726, an ash plume rose around 1 km above the summit and drifted SW. According to the Darwin Volcanic Ash Advisory Centre (VAAC), ash plumes were identified in satellite images rising 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted W and NW during 24-27 October. A news article from 26 October noted that lava flows or incandescent avalanches of material descended the flanks 200-700 m S, as far as 1 km SW and W, and 500-700 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, lava fountaining, and lava flows from vents along the SW and W margins of Halemaʻumʻu Crater, continued at variable levels during 21-28 October. Incandescence at the N and W vents was variable throughout the week; the S vent was covered with tephra and was not incandescent. During an overflight on 24 October scientists observed that the N vent was crusted over and the W vent had a slowly convecting lava pond within it. The Volcano Alert Level remained at Advisory (the second lowest level on a four-level scale) and the Aviation Color Code remained at Yellow (the second lowest color on a four-color scale).

Geological summary: Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the Island of 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.

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 22-28 October. A daily thermal anomaly was identified in satellite images. Small temperature anomalies along the active lava flow on the ENE flank were visible in a clear satellite image from 20 October. 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).

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 at Langila rose 1.5-2.4 km (5,000-8,000 ft) a.s.l. and drifted NW, N, NE, and SW during 26-28 October based, on satellite images. On 28 October the VAAC noted that smoke from extensive fires in the area was also identified in satellite data.

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.

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 22-28 October. White steam-and-gas plumes rose as high as 100 m above the summit and drifted NW, W, and SW during 22-23 and 28 October. White-and-gray ash plumes rose 200-300 m above the summit and drifted W and NW on 24 October. That same day, at 2340, a webcam image showed incandescent material being ejected above the summit and onto the flanks. 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.

Manam, Papua New Guinea

4.08°S, 145.037°E; Elev. 1,807 m

The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume from Manam rose to 2.7 km (9,000 ft) a.s.l. and drifted NE on 23 October. The plume had dissipated within about four hours.

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 22-28 October. An eruptive event was recorded at 2226 on 26 October by the seismic network but was not visually observed due to weather conditions and/or darkness. 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.

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 21-28 October. The seismic network recorded 3-14 daily volcanic earthquakes and one rockfall event on 26 October. Sulfur dioxide emissions averaged 700-3,317 tonnes per day. Emissions rose as high as 400 m above the crater and drifted in multiple directions on most days; weather conditions obscured views during 22-23 October. Minor Strombolian activity was visible on 24 October and an ash emission lasted for 32 seconds. On 25 October an ash emission lasted for 51 seconds. 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 22-28 October, with avalanches produced by the active lava dome on the upper SW flank. Two lava avalanches traveled as far as 1.5 km down Krasak drainage on the SW flank on 22 October. 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 Geológico Colombiano (SGC) reported that eruptive activity at Puracé continued during 20-26 October. Seismicity indicating fluid movement occurred beneath Puracé and Piocollo volcanoes at depths less than 3 km. Seismicity related to rock-fracturing, volcano-tectonic (VT) events, was at a similar level as the previous week. The VT events were located 12-18 km NE at depths of 7-14 km and beneath the Puracé and Piocollo volcanoes at depths of 1-4 km and had low magnitudes. Sulfur dioxide and carbon dioxide levels were characterized as significant. Low-energy thermal anomalies on the crater floor were identified in satellite data. Continuous gas emissions and a total of 31 ash emissions were recorded. Plumes rose as high as 2.1 km above the summit of Puracé and drifted mainly W and NW. Residents of Coconuco, Puracé, and Paletará observed some of these emissions. 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 19-25 October. The seismic network detected 33 seismic events associated with the movement of magmatic fluids, along with earthquakes indicating internal rock fracturing; no volcanic explosions occurred during the week. Gas, steam, and ash emissions periodically rose as high as 600 m above the summit and drifted less than 10 km SE and E. Moderate sulfur dioxide emissions averaged 725 tons per day, and four 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.

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 22-28 October, with daily eruptive events recorded by the seismic network. White-to-gray or gray ash plumes rose 200-1,200 m above the summit and drifted SE, S, SW, and W during 22-24 October; emissions were not visible due to weather conditions on the other days. 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 21-28 October. A thermal anomaly was identified in satellite images on most days; weather clouds sometimes 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.

Suwanosejima, Japan

29.638°N, 129.714°E; Elev. 796 m

The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima’s Otake Crater continued during 16-23 October. Crater incandescence was observed at night with a high-sensitivity camera. An eruptive event on 17 October produced an ash plume that rose 400 m above the crater rim. Rumbling was heard in areas within 5 km according to the Suwanosejima Branch Office in Toshima village (3.5 km SSW). The Alert Level remained at 2 (the second level on a five-level scale) and the public was warned to be cautious within 1.5 km of the crater.

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 21-28 October. The seismic network recorded 0-29 daily volcanic earthquakes, including periods of volcanic tremor on most days, lasting between one minute to more than a day. Daily gas-and-steam emissions generally rose as high as 3 km above the crater rim and drifted in multiple directions. Sulfur dioxide emissions averaged 485-575 tonnes per day during 21 and 22-23 October, respectively. Two minor phreatomagmatic eruptions on 21 October lasted 2-3 minutes. A minor phreatomagmatic eruption lasted for four minutes the next day. 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.

Yasur, Vanuatu

19.532°S, 169.447°E; Elev. 361 m

The Vanuatu Meteorology and Geohazards Department (VMGD) reported that activity at Yasur continued at a level of “major unrest,” as defined by the Alert Level 2 status (on a scale of 0-5) in October. Seismic data confirmed continuing volcanic activity with explosions that were occasionally strong to very strong and persistent volcanic tremor. Webcam and satellite images during September-October recorded frequent explosions, nighttime crater incandescence, and dense plumes of gas, steam, and/or ash. Sulfur dioxide gas emissions identified in satellite images were at variable levels. Low-to-moderate thermal anomalies persisted. According to the Wellington Volcanic Ash Advisory Center (VAAC) ash plumes generated by ongoing, low-level activity were visible in satellite and webcam images on 27 October rising 0.9-1.2 km (3,000-4,000 ft) a.s.l. and drifting W. The public was reminded to not enter the restricted area within 600 m around the boundaries of the Permanent Exclusion Zone, defined by Danger Zone A on the hazard map.

Geological summary: Yasur has exhibited essentially continuous Strombolian and Vulcanian activity at least since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Located at the SE tip of Tanna Island in Vanuatu, this pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide open feature associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century.

References:

¹ Smithsonian Institution / US Geological Survey Weekly Volcanic Activity Report – GVP – October 22-28, 2026 – Managing Editor: Sally Sennert