The Weekly Volcanic Activity Report: May 7–13, 2025

New activity/unrest: Bezymianny, Russia | Bulusan, Philippines | Kanlaon, Philippines | Klyuchevskoy, Russia | Raung, Indonesia.

New activity/unrest

Bezymianny, Russia

55.972°N, 160.595°E | Summit elev. 2882 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a thermal anomaly over Bezymianny was identified in satellite images from May 1 to 8. According to the Institute of Volcanology and Seismology (IVS) of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), crater incandescence was visible during dark hours on most days, though weather clouds mostly obscured views during May 5 and 6. Hot avalanches of material descended the flanks from May 1 to 3. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates are reported in UTC; specific events are in local time where noted.

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 between 11 000 and 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 1955–56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open crater that was formed by the 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.

Bulusan, Philippines

12.769°N, 124.056°E | Summit elev. 1535 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing unrest at Bulusan from May 6 to 12, 2025. The seismic network recorded 18 to 124 daily volcanic earthquakes. Voluminous gas-and-steam emissions rose as high as 400 m (1 312 feet) above the summit and drifted northwest, west-northwest, west, and west-southwest. Daily averages of sulfur dioxide emissions ranged from 466 to 1 117 tonnes per day; emissions were not reported on May 11. A special advisory was issued on May 12 due to increasing seismicity. From 00:00 on May 8 until 13:30 on May 12, the seismic network recorded 309 volcanic earthquakes; of those, 287 were volcano-tectonic earthquakes, indicating rock fracturing at shallow depths (less than 4 km (2.5 miles)) beneath the southeastern flank, and 22 were low-frequency earthquakes associated with fluid movement. The Alert Level remained at 1 (the second lowest level on a scale of 0–5). The public was reminded not to enter the 4 km (2.5 miles) radius Permanent Danger Zone (PDZ) and to be vigilant within the 2 km (1.2 miles) Extended Danger Zone (EDZ) on the southeastern flank.

Geological summary: Luzon’s southernmost volcano, Bulusan, was constructed along the rim of the 11 km (6.8 miles)-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36 000 years ago. It lies at the southeastern end of the Bicol volcanic arc, occupying the peninsula of the same name that forms the elongated southeastern tip of Luzon. A broad, flat moat is located below the topographically prominent southwestern rim of Irosin caldera; the northeastern rim is buried by the andesitic complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the southwestern flank and Sharp Peak to the northeast. The summit is unvegetated and contains a 300 m (984 feet) wide, 50 m (164 feet) deep crater. Three small craters are located on the southeastern flank. Many moderate explosive eruptions have been recorded since the mid-19^th century.

Kanlaon, Philippines

10.4096°N, 123.13°E | Summit elev. 2422 m

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon from May 6 to 13, 2025. Daily sulfur dioxide emissions ranged from 554 to 3 055 tonnes per day. Gas-and-steam plumes with occasional ash content rose as high as 1 km (3 280 feet) above the crater rim and drifted northwest, west, southwest, and southeast. Periods of ash emissions were noted on May 8 (5 minutes) and May 11 (27 minutes). The seismic network recorded 5 to 10 daily volcanic earthquakes from May 6 to 10 and 63 volcanic earthquakes on May 11. A total of 135 volcanic earthquakes were detected by the seismic network from 00:00 on May 11 to 12:00 on May 12, including relatively strong volcano-tectonic earthquakes, indicating rock fracturing due to rising magma or gases. A total of 72 volcanic earthquakes (M0.3–3.1) recorded from 00:00 to 12:00 on May 12 were located 0 to 8 km (0 to 5 miles) beneath the northern and northwestern flanks. PHIVOLCS issued an advisory at 13:30 on May 12, noting increased seismicity.

A moderately explosive eruption began at 02:55 on May 13 and lasted for five minutes based on seismic and infrasound data. Audible rumbling sounds were heard in barangays in Negros Oriental, including Pula and Canlaon City (10 km (6.2 miles) east-southeast), and in La Castellana (16 km (9.9 miles) southwest) in Negros Occidental. A voluminous grayish ash plume rose about 4.5 km (14 764 feet) above the summit and drifted southwest. Incandescent pyroclastic density currents descended the southern flanks as far as 2 km (1.2 miles) based on visual and thermal camera monitoring. Large fragments were ejected from the crater a few hundred meters and set vegetation near the summit on fire. Minor ashfall was reported in the barangays of Yubo and Ara-al (La Carlota City, 14 km (8.7 miles) west), in Ilijan and Binubuhan (Bago City, 30 km (18.6 miles) northwest), and in Biak-na-Bato, Sag-ang, and Mansalanao (La Castellana). According to news articles, additional reports of ashfall came from San Carlos City (31 km (19.3 miles) east-northeast) and Bacolod (35 km (21.7 miles) northwest), as well as from the municipalities of Murcia (24 km (14.9 miles) northwest), San Enrique (29 km (18 miles) west), Valladolid (34 km (21.1 miles) west), Pontevedra (29 km (18 miles) west-southwest), Hinigaran (35 km (21.7 miles) southwest), and Binalbagan (38 km (23.6 miles) southwest). A sulfur odor was also reported in several localities. According to the Tokyo VAAC, the ash plume rose to 7.9 km (26 000 feet) above sea level, or 5.5 km (18 045 feet) above the summit. Dozens of flights in and out of the affected areas were cancelled, and others were delayed or rerouted on May 13 and 14. The Alert Level remained at 3 (on a scale of 0–5); the public was warned to stay 6 km (3.7 miles) away from the summit and pilots were warned not to fly close to the volcano.

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 (20.5 miles) southwest from Kanlaon. The summit contains a 2 km (1.2 miles)-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.

Klyuchevskoy, Russia

56.056°N, 160.642°E | Summit elev. 4754 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a thermal anomaly at Klyuchevskoy was identified in satellite images on May 1, 4, and from May 6 to 8. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates are based on UTC; specific events are in local time where noted.

Geological summary: Klyuchevskoy is the highest and most active volcano on the Kamchatka Peninsula. Since its origin about 6 000 years ago, this symmetrical basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle northeast of Kamen volcano and lies southeast of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during approximately the past 3 000 years, with most lateral craters and cones occurring along radial fissures between the unconfined northeast-to-southeast flanks of the conical volcano between 500 and 3 600 m (1 640 and 11 811 feet) elevation. Eruptions recorded since the late 17th century have resulted in frequent changes to the morphology of the 700 m (2 297 feet)-wide summit crater. These eruptions over the past 400 years have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Raung, Indonesia

8.119°S, 114.056°E | Summit elev. 3260 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that at 05:09 on May 9, an ash plume rose around 1 km (3 280 feet) above Raung’s summit crater rim and drifted north and northwest. The Alert Level remained at 2 (on a scale of 1–4), and the public was warned to stay 3 km (1.9 miles) away from the summit crater.

Geological summary: Raung, one of Java’s most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed southwest of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2 km (1.2 miles) wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the western flank produced a large debris avalanche that traveled 79 km (49 miles), reaching nearly to the Indian Ocean. Raung contains several centers constructed along a northeast–southwest line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the northeast and west, respectively.

Ongoing activity

Dukono, Indonesia

1.6992°N, 127.8783°E | Summit elev. 1273 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued from May 7 to 13. Daily gas-and-ash plumes rose 100 to 1 500 m (328 to 4 921 feet) above the summit and drifted east, southeast, and south. The Alert Level remained at Level 2 (on a scale of 1–4), and the public was warned to stay 4 km (2.5 miles) 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 (6.2 miles) northeast. Malupang Wariang, 1 km (0.6 miles) southwest of the summit crater complex, contains a 700 x 570 m (2 297 x 1 870 feet) crater that has also had reported eruptions.

Etna, Italy

37.748°N, 14.999°E | Summit elev. 3357 m

The Sezione di Catania – Osservatorio Etneo (INGV) reported continuing eruptive activity at Etna’s southeast crater and gas emissions at Bocca Nuova Crater, northeast crater, and Voragine during May 5 to 11. Strombolian activity at the southeast crater began in the late morning of May 5, though weather clouds obscured visual observations. An eruption cloud drifted downwind and caused minor ashfall along the east-northeast flank, reaching the town of Fiumefreddo di Sicilia, 19 km (11.8 miles) east-northeast. Two small lava flows descended the flank of the southeast crater, with the shorter flow to the south.

Geological summary: Mount Etna, towering above Catania on the island of Sicily, has one of the world’s longest documented records of volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km (3.1 x 6.2 miles) caldera open to the east. Two styles of eruptive activity typically occur, sometimes simultaneously. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more summit craters. Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by Strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the southeast flank.

Fuego, Guatemala

14.4748°N, 90.8806°W | Summit elev. 3799 m

The Instituto Nacional de Sismología, Vulcanología, Meteorología e Hidrología (INSIVUMEH) reported continued eruptive activity at Fuego from May 6 to 13. Daily explosions were recorded by the seismic network at rates of 1 to 8 per hour. Incandescent material was observed at night being ejected 100 to 300 m (328 to 984 feet) above the summit. The explosions generated gas-and-ash plumes that rose as high as 1.1 km (3 609 feet) above the summit and drifted as far as 30 km (18.6 miles) west and southwest. Rumbling sounds and shock waves were occasionally reported. Explosions sometimes generated block avalanches around the crater that descended the Santa Teresa (west) and Ceniza (south-southwest) drainages. Ashfall was reported in Panimache I and II (8 km (5 miles) southwest), Morelia (10 km (6.2 miles) southwest), Santa Sofía (12 km (7.5 miles) southwest), El Porvenir (11 km (6.8 miles) southwest), Finca la Asunción (12 km (7.5 miles) southwest), and surrounding areas on a few of the days. During the afternoon of May 10, a lahar descended the Ceniza drainage, carrying tree branches, trunks, and blocks as large as 3 m (9.8 feet) in diameter.

Geological summary: Volcán Fuego, one of Central America’s most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230 000 years ago 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 (31 miles) 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 | Summit elev. 1740 m

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin’s summit crater from May 7 to 13. Small daily earthquakes were detected by the seismic network. No unusual activity was observed in satellite and webcam views, though weather clouds often obscured views of the volcano. 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 (0.5 x 0.75 miles) 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 of up to 6 m (19.7 feet). 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 north-northwest-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 19^th century.

Home Reef, Tonga

18.992°S, 174.775°W | Summit elev. -10 m

The Tonga Geological Services reported continuing activity at Home Reef from May 3 to 11. Moderate thermal anomalies were detected by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system only on May 4, though persistent weather clouds hindered observations. Infrasound instruments did not detect any signals. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale). The Maritime Alert Level remained at Orange (the third level on a four-level scale), with advice to stay at least 2 nautical miles (3.7 km / 2.3 miles) from the island. The Alert Level for residents of Vava’u and Ha’apai remained at Green (the first level on a four-level scale).

Geological summary: Home Reef, a submarine volcano midway between Metis Shoal and Late Island in the central Tonga Islands, was first reported active in the mid-19th century, when an ephemeral island formed. An eruption in 1984 produced a 12 km (7.5 miles)-high eruption plume, large amounts of floating pumice, and an ephemeral 500 x 1 500 m (1 640 x 4 921 feet) island, with cliffs 30 to 50 m (98 to 164 feet) high that enclosed a water-filled crater. In 2006, an island-forming eruption produced widespread dacitic pumice rafts that drifted as far as Australia. Another island was built during a September–October 2022 eruption.

Ibu, Indonesia

1.488°N, 127.63°E | Summit elev. 1325 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued from May 7 to 13. Daily gray, white-to-gray, or white-to-brown ash plumes rose 300 to 800 m (984 to 2 625 feet) above the summit and drifted in various directions. Nighttime crater incandescence was visible in some webcam images. The Alert Level remained at 3 (the second highest level on a four-level scale), and the public was advised to stay 4 km (2.5 miles) away from the active crater and 5 km (3.1 miles) away from the northern crater wall opening.

Geological summary: The truncated summit of Gunung Ibu stratovolcano along the northwest coast of Halmahera Island has large nested summit craters. The inner crater, 1 km (0.6 miles) wide and 400 m (1 312 feet) deep, has contained several small crater lakes. The 1.2 km (0.75 miles) wide outer crater is breached on the north, creating a steep-walled valley. A large cone grew east-northeast of the summit, and a smaller one to the west-southwest has fed a lava flow down the western flank. A group of maars is located below the northern and western 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.

Karymsky, Russia

54.049°N, 159.443°E | Summit elev. 1513 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that thermal anomalies over Karymsky were identified in satellite images from May 1 to 3 and on May 7. Ash clouds drifted 25 km (15.5 miles) east on May 1. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC; specific events are in local time where noted.

Geological summary: Karymsky, the most active volcano of Kamchatka’s eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5 km (3.1 miles) wide caldera that formed during the early Holocene. The caldera cuts the southern side of the Pleistocene Dvor volcano and is located outside the northern margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7 600 to 7 700 radiocarbon years ago; construction of the stratovolcano began about 2 000 years later. The latest eruptive period began about 500 years ago, following a 2 300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian, with moderate explosive activity and occasional lava flows from the summit crater.

Kilauea, United States

19.421°N, 155.287°W | Summit elev. 1222 m

The Hawaiian Volcano Observatory (HVO) reported that the eruption within Kilauea’s Kaluapele summit caldera, from two vents along the southwest margin of Halemaʻumaʻu Crater, continued at variable levels from May 7 to 13. Visible incandescence from the May 6 lava flows on the crater floor decreased from May 7 to 9. Incandescence at both the northern and southern vents was visible from May 7 to 11. Occasional spattering at the northern vent occurred between 04:00 and 05:30 on May 9.

Intermittent spatter, hydrogen flames, and low-level lava fountains were observed at the northern vent overnight from May 10 to 11. Lava fountaining was observed specifically at 04:20, 05:30, 08:00, 08:30, and 09:10 on May 11, followed by additional numerous small fountains. The last three specified events were characterized by cycles of dome fountaining, lava ponding, and lava drainbacks. Sustained lava fountains that began at 12:45 quickly grew in vigor and height, rising over 150 m (492 feet) within an hour. Intense sulfur dioxide emissions—estimated to be around 50 000 tonnes per day—accompanied the ejection of tephra and the formation of Pele’s Hair. Lava flows advanced more than 1 km (0.62 miles) along the northern edge of the crater floor. The fountain heights cycled from 60 m to more than 150 m (197 to 492 feet) at about 10-minute intervals between 14:00 and 16:00, recorded as oscillations in tremor data. After 16:00, the height was more consistent, averaging 120 m (394 feet) until the activity ceased at 20:34. Overall, fountaining was sustained for seven hours and 51 minutes. Minor fountaining to 15 m (49 feet) began at the southern vent just before the activity at the northern vent ceased, and then stopped at 20:36. Lava covered about 50 percent of the crater floor. Incandescence at both the northern and southern vents was visible overnight from May 11 to 12. 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: Kilauea overlaps the eastern flank of the massive Mauna Loa shield volcano on the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaʻumaʻu Crater in the summit caldera until 1924. The 3 x 5 km (1.9 x 3.1 miles) caldera was formed in several stages about 1 500 years ago and during the 18^th century. Eruptions have also originated from the lengthy East and Southwest Rift Zones, which extend to the ocean in both directions. About 90 percent of the surface of the basaltic shield volcano is formed of lava flows less than about 1 100 years old; 70 percent 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 (38.6 mi²), destroyed hundreds of houses, and added new coastline.

Lewotobi, Indonesia

8.542°S, 122.775°E | Summit elev. 1703 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Lewotobi Laki-laki continued from May 7 to 13. Daily white plumes rose as high as 1 km (3 280 feet) above the crater rim and drifted in various directions. At 20:17 on May 11, a dense gray ash plume rose 300 m (984 feet) above the crater rim and drifted north and northeast. The eruptive event lasted 55 seconds based on seismic data. The Alert Level remained at 3 (on a scale of 1–4), and the public was warned to stay 6 km (3.7 miles) away from the center of Laki-laki.

Geological summary: The Lewotobi edifice on eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (“the husband and wife”). Their summits are less than 2 km (1.2 miles) apart along a northwest–southeast line. The conical Laki-laki to the northwest has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the eastern flank of Perempuan.

Lewotolok, Indonesia

8.274°S, 123.508°E | Summit elev. 1431 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruption at Lewotolok was ongoing from May 6 to 13. Daily white steam-and-gas plumes rose as high as 500 m (1 640 feet) above the summit of the cone and drifted in multiple directions. A few nighttime webcam images showed incandescent material being ejected above the summit. At 12:35 on May 11, a white-and-gray ash plume rose around 500 m (1 640 feet) above the summit and drifted east. The Alert Level remained at 2 (on a scale of 1–4), and the public was warned to stay 2 km (1.2 miles) away from the vent and 2.5 km (1.6 miles) away on the southern, southeastern, and western 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 (427 feet)-wide crater constructed at the southeastern 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.

Marapi, Indonesia

0.38°S, 100.474°E | Summit elev. 2885 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity from Verbeek Crater at Marapi (on Sumatra) continued from May 7 to 13. On May 7, dense gray-and-white ash plumes rose as high as 500 m (1 640 feet) above the crater rim and drifted north and northeast. On May 8, white-and-brown ash plumes rose 250 to 400 m (820 to 1 312 feet) above the crater rim and drifted northeast, east, and southeast. White plumes were visible rising as high as 150 m (492 feet) above the crater rim from May 9 to 11 and drifted east, southeast, and south. At 03:10 on May 12, a dense gray ash plume rose 600 m (1 969 feet) above the crater rim and drifted southeast. The Alert Level remained at 2 (on a scale of 1–4), and the public was warned to stay 3 km (1.9 miles) 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 2 000 m (6 562 feet) above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4 km (0.87 miles)-wide Bancah caldera. The summit craters are located along an east-northeast to west-southwest 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 reported in historical time.

Merapi, Indonesia

7.54°S, 110.446°E | Summit elev. 2910 m

The Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG) reported that the eruption at Merapi (on Java) continued from May 2 to 8. Seismicity remained at high levels. The southwest lava dome produced 41 lava avalanches that traveled as far as 2 km (1.2 miles) southwest down the Bebeng drainage, 10 that traveled as far as 1.8 km (1.1 miles) southwest down the Krasak drainage, and 73 that traveled as far as 2 km (1.2 miles) west down the Sat/Putih drainage. Small morphological changes to the southwest lava dome resulted from continuing effusion and minor collapses of material. The Alert Level remained at 3 (on a scale of 1–4), and the public was warned to stay 3 to 7 km (1.9 to 4.3 miles) 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 north-northwest 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 southwest 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.

Poas, Costa Rica

10.2°N, 84.233°W | Summit elev. 2697 m

The Observatorio Vulcanológico y Sismológico de Costa Rica – Universidad Nacional (OVSICORI-UNA) reported continuing gas-and-steam emissions that occasionally contained ash at Poás from May 6 to 13. Inflation continued to be detected. Sulfur dioxide emissions were as high as 1 703 tonnes per day on May 6. Some water had pooled at Boca C and was bubbling, based on a drone observation that same day. Ash was very low or not detected in the steam-and-gas plumes from May 5 to 7. Overnight during May 7 to 8, incandescence reflected in the emissions from sulfur combustion suggested temperatures below 300°C (572°F). A significant eruptive event was detected in seismic and acoustic data at 14:04 on May 8 and lasted for two minutes. Weather conditions prevented direct visual observations of the event, though the seismic and acoustic data suggested an ash-and-gas plume rising into the 1 to 4 km (3 280 to 13 120 feet) high range; wind direction was to the southwest. Bubbling at Boca C was again observed. Overnight during May 8 to 9, intense incandescence emanated from Boca A and a dense steam plume with minor ash content was observed. Continuous gas-and-steam plumes drifted southwest from May 12 to 13; the plumes were more intense from Boca A, where overnight incandescence was also observed. The Alert Level remained at 3 (the second highest level on a four-level scale) and the Aviation Color Code remained at Orange (the second highest color on a four-color scale).

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

Sabancaya, Peru

15.787°S, 71.857°W | Summit elev. 5960 m

The Instituto Geofísico del Perú (IGP) reported low levels of unrest at Sabancaya from May 5 to 11, with no explosions, thermal anomalies, or significant deformation. Gas-and-steam plumes rose as high as 1 km (3 280 feet) above the summit and drifted less than 10 km (6.2 miles) southwest and southeast. Sulfur dioxide emissions were at low levels, averaging 211 tonnes per day. The Alert Level was lowered to Yellow (the second level on a four-color scale) on May 12, and the public was warned to stay outside of a 6 km (3.7 miles) radius from the summit.

Geological summary: Sabancaya, located in the saddle northeast of Ampato and southeast 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 except the south. Records of observed eruptions date back to 1750 CE.

Santa Maria, Guatemala

14.757°N, 91.552°W | Summit elev. 3745 m

The Instituto Nacional de Sismología, Vulcanología, Meteorología e Hidrología (INSIVUMEH) reported ongoing eruptive activity at Santa María’s Santiaguito dome complex from May 6 to 13, with continuing lava extrusion at the Caliente dome. Daily explosions—up to five per hour when reported—sometimes generated gas-and-ash plumes that rose as high as 1 km (3 280 feet) above the dome and possibly drifted as far as 15 km (9.3 miles) east, south, southwest, and west. Effusion of blocky lava and collapses of material produced block avalanches that descended multiple flanks; the collapsed material sometimes generated short pyroclastic flows. Incandescence was visible at Caliente dome and the upper part of the southwest flank lava flow. During the evening of May 10, heavy rainfall generated lahars in the Tambor drainage (south-southwest) that carried blocks up to 1 m (3.3 feet) in diameter mixed with fine sediment, tree trunks, and branches. Ashfall was reported in San Marcos (10 km (6.2 miles) southwest), Loma Linda (7 km (4.3 miles) west), and Palajunoj (17 km (10.6 miles) south-southwest) during May 12 and 13.

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 southwest flank by a 1.5 km (0.93 miles)-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 southwestern 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 east 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 | Summit elev. 3657 m

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that activity continued at Semeru from May 7 to 13, with multiple daily eruptive events recorded by the seismic network. Daily white-and-gray ash plumes rose 400 to 1 000 m (1 312 to 3 280 feet) above the summit and drifted in multiple directions. Weather clouds mostly obscured views on May 7. The Alert Level remained at 2 (the second lowest level on a scale of 1–4). The public was warned to stay at least 5 km (3.1 miles) away from the summit in all directions, 13 km (8.1 miles) from the summit to the southeast, 500 m (1 640 feet) from the banks of the Kobokan drainage as far as 17 km (10.6 miles) from the summit, and to avoid other drainages including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

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 north–south trend cutting through the summit, and cinder cones and lava domes occupy the eastern and northeastern flanks. Summit topography is complicated by the shifting of craters from northwest to southeast. 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 | Summit elev. 3283 m

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that lava extrusion may have continued at Sheveluch’s “300 years of RAS” dome on the southwest flank of Old Sheveluch and at the Young Sheveluch dome from May 1 to 8. Thermal anomalies over the domes were identified in satellite images almost daily. 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 north-northeast of the Kliuchevskaya volcano group. The 1 300 km³ (312 mi³) 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 the roughly 65 000-year-old Stary Shiveluch is truncated by a broad 9 km (5.6 miles)-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 | Summit elev. 924 m

The Sezione di Catania – Osservatorio Etneo (INGV) reported that eruptive activity continued at Stromboli from May 5 to 11. Webcam images showed Strombolian activity at four vents in Area N within the upper part of the Sciara del Fuoco and from at least two vents in Area C-S (South-Central Crater) on the crater terrace. The vents in Area N continued to produce low- to medium-intensity explosions at a rate of 6 to 9 events per hour, ejecting lapilli and bombs less than 150 m (492 feet) above the vents. Low- to medium-intensity explosions at the vents in Area C-S ejected ash, bombs, and lapilli above the vent at a rate of 2 to 5 events per hour. 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 northeastern 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 and extends below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the northwest. 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 | Summit elev. 796 m

The Japan Meteorological Agency (JMA) reported that eruptive activity at Suwanosejima’s Ontake Crater continued from May 5 to 12. Incandescence was observed nightly in webcam images. No explosions were detected, though plumes from eruptive events rose 900 m (2 953 feet) above the crater rim. 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 (0.9 miles) of the crater.

Geological summary: The 8 km (5 miles) 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 eastern 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 northeastern summit crater, between 1949 and 1996, after which periods of inactivity lengthened. The largest recorded eruption took place in 1813–1814, when thick scoria deposits covered residential areas, and the southwestern crater produced two lava flows that reached the western coast. At the end of the eruption, the summit of Otake collapsed, forming a large debris avalanche and creating an open collapse scarp extending to the eastern coast. The island remained uninhabited for about 70 years after the 1813–1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Whakaari/White Island, New Zealand

37.52°S, 177.18°E | Summit elev. 294 m

On May 13, GeoNet reported near-continuous emissions of gas, steam, and minor amounts of ash at Whakaari/White Island based on visual observations during overflights, observations from the Bay of Plenty coast, and webcams located at Whakatāne and Te Kaha. Additionally, minor amounts of ash were identified in satellite data as reported by the Wellington Volcanic Ash Advisory Center (VAAC). As seen from the coast, the plume occasionally rose 300 to 600 m (984 to 1 968 feet) above the summit during calm weather conditions. Under windier conditions, the plume was lower and visible downwind for tens of kilometers. Flights were occasionally canceled due to ash in the air.

During overflights, scientists observed that the vent had not notably changed in size or shape. Although the vent temperature had increased to 460°C (752°F), it remained below the peak of 650°C (1 202°F) recorded in 2020 and 2021. Elevated temperatures were visible at night in the Te Kaha camera’s near-infrared images. Fewer new impact craters were seen around the vent, suggesting reduced explosive activity. Temperature measurements, sulfur dioxide emissions identified in satellite data, and ash content in the emissions have remained steady over the past few months. 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). GeoNet noted that the Alert Levels reflect current activity, though uncertainty remains due to the lack of consistent, usable real-time monitoring data; monitoring currently relies on remote cameras, satellite imagery, and periodic overflights.

Geological summary: The uninhabited Whakaari/White Island is the 2 x 2.4 km (1.2 x 1.5 miles) emergent summit of a 16 x 18 km (9.9 x 11.2 miles) submarine volcano in the Bay of Plenty, about 50 km (31 miles) offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The southeastern side of the crater is open at sea level, with recent activity centered about 1 km (0.6 miles) from the shore near the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km (3.1 miles) northwest. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity at the volcano also features prominently in Māori oral tradition. The formation of many new vents during the 19^th and 20^th centuries caused rapid changes in crater floor topography. The collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining operation. Explosive activity in December 2019 occurred while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Māori name Te Puia o Whakaari (“The Dramatic Volcano”) and White Island, named by Captain James Cook in 1769 in reference to the constant steam plume.

References:

¹ Smithsonian Institution / US Geological Survey – GVP – Weekly Volcanic Activity Report May 7–13, 2025 – Managing Editor: Sally Sennert

Teo Blašković

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