The Weekly Volcanic Activity Report: March 6 - 12, 2024

New activity/unrest was reported for 3 volcanoes from March 6 to 12, 2024. During the same period, ongoing activity was reported for 19 volcanoes.

New activity/unrest: Ahyi, Mariana Islands (USA) | Fernandina, Isla Fernandina (Galapagos) | Masaya, Nicaragua.

New activity/unrest

Ahyi, Mariana Islands (USA)

20.42°N, 145.03°E | Summit elev. -75 m

Signs of unrest at Ahyi Seamount continued. A small plume of discolored seawater in the vicinity of the seamount was observed in a 5 March satellite image. 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 that rises to within 75 m of the ocean surface ~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.

Fernandina, Isla Fernandina (Galapagos)

0.37°S, 91.55°W | Summit elev. 1476 m

IG-EPN reported that the eruption at Fernandina continued during 6-12 March from a circumferential fissure located on the upper SE flank, though gradually decreased during the week. Hundreds of thermal anomalies over the lava flows were identified daily in satellite images during 5-8 March, and the longest lava flow advanced 100 m to a total length of 8 km. Gas emissions associated with the emplacement of lava flows drifted WSW. A fire W of the flow field was observed on 7 March. During 8-11 March dozens of thermal anomalies were identified daily in satellite images. Sulfur dioxide emissions measured from satellite were variable, with measurements between about 1,870 and 4,160 tons per day during 7-10 March.

Geological summary: Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic “overturned soup bowl” profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 km3 section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake.

Masaya, Nicaragua

11.9844°N, 86.1688°W | Summit elev. 594 m

According to news articles, INETER reported that gas emissions increased at Masaya’s Santiago Crater in February, small landslides occurred from the inner NW crater wall, and the level of the lava lake had slightly increased. The report noted that SINAPRED recommended limits on the number of people and the time spent at the viewing area at the crater rim. A larger landslide occurred on 2 March and covered the active lava lake. A satellite image from 3 March showed a much smaller thermal anomaly on the crater floor compared to a 22 February image. According to an 8 March news article, INETER reported that small landslides continued to occur, originating from the inner SW and NW crater walls; a more notable landslide was recorded at 0900. The lava lakes remained covered with the deposits. Constant gas emissions rose from vents possibly on the crater floor and from fractures on the inner walls, though the gas flux was at lower rate, estimated to be 25-30 percent of the normal values. Seismicity was low with RSAM values around 23. The report noted that the Parque Nacional Volcán Masaya may partially open, though the public was warned to stay 800 m away from Santiago Crater.

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

Ongoing activity

Aira, Kyushu (Japan)

31.5772°N, 130.6589°E | Summit elev. 1117 m

JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera’s Sakurajima volcano) during 4-11 March with nighttime crater incandescence. Very small eruptive events occasionally occurred during 4-8 March. An explosion at 0359 on 9 March produced an ash plume that rose 800 m above the crater rim and drifted SE, and ejected large blocks 1.3-1.7 km from the vent. Eruptive events at 1540 on 10 March and at 0532 on 11 March generated ash plumes that rose 1.2-1.3 km above the crater rim and drifted E. An ash plume from an explosion at 2132 on 11 March rose 1.4 km above the crater rim and drifted NE; large blocks were ejected 500-700 m from the vent. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both 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 | Summit elev. 1496 m

On 8 March the Vanuatu Meteorology and Geohazards Department (VMGD) reported that emissions from the active vents at Ambae were ongoing based on recent field observations and photographs. The emissions contained gas, or steam, or ash, or some combination of all three. The Alert Level remained at 2 (on a scale of 0-5), and the public was warned to stay outside of the Danger Zone, defined as a 2-km radius around the active vents in Lake Voui, and away from drainages during heavy rains.

Geological summary: The island of Ambae, also known as Aoba, is a massive 2,500 km3 basaltic shield that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone with numerous scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes (Manaro Ngoru, Voui, and Manaro Lakua) is located at the summit within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. That large central edifice is also called Manaro Voui or Lombenben volcano. Post-caldera explosive eruptions formed the summit craters about 360 years ago. A tuff cone was constructed within Lake Voui (or Vui) about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Ebeko , Paramushir Island (Russia)

50.686°N, 156.014°E | Summit elev. 1103 m

KVERT reported that moderate explosive activity was ongoing at Ebeko during 29 February-6 March. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions on 29 February and 1 and 6 March generated ash plumes that rose as high as 3 km (10,000 ft) a.s.l. and drifted NW, E, and SE. Ashfall was reported in Severo-Kurilsk on 6 March. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.

Geological summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Fuego, South-Central Guatemala

14.473°N, 90.88°W | Summit elev. 3763 m

INSIVUMEH reported that eruptive activity continued at Fuego during 6-12 March. Explosions were recorded daily, averaging 3-10 per hour on most days, when counts were reported. The explosions generated gas-and-ash plumes that rose as high as 1.1 km above the crater rim and drifted as far as 30 km in multiple directions. Explosions caused frequent block avalanches that descended various drainages including the Ceniza (SSW), Seca (W), Taniluyá (SW), and Las Lajas (SE), and sometimes reached vegetated areas. The explosions also ejected incandescent material 100-300 m above the summit on most days and occasionally ejected ballistics as far as 2 km. Weak rumbling sounds and shock waves were frequently reported. Ashfall was reported in areas downwind including Fincas La Candelaria, La Reunión (7 km SE), El Porvenir (11 km SW), El Rodeo, Finca Palo Verde, Sangre de Cristo (8 km WSW), Yepocapa (8 km NW), La Soledad (11 km N), Acatenango (8 km E), Parramos (18 km NNE), and other nearby communities during 5-6 and 10-11 March; ashfall was forecasted for downwind areas on most of the other days.

Geological summary: Volcán Fuego, one of Central America’s most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala’s former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical 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, Andreanof Islands (USA)

52.076°N, 176.13°W | Summit elev. 1740 m

AVO reported that continuing slow lava effusion in Great Sitkin’s summit crater was last confirmed in a 9 March radar satellite image with continuing inflation over the vent and advancement of the NW lava flow; effusion likely continued during 10-12 March. Seismicity was low. Slightly elevated surface temperatures were identified in satellite images during 5-8 March. 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.

Huaynaputina, Peru

16.6144°S, 70.8542°W | Summit elev. 4679 m

Instituto Geofísico del Perú (IGP) reported that at 1553 on 6 March a lahar descended the El Volcán drainage, on the S flank of Huaynaputina, and traveled towards the Tambo River. The public was warned to stay away from the drainage and to be cautious when traveling along the Quinistaquillas-Sijuaya highway.

Geological summary: Huaynaputina (whose name means “new volcano”) was the source of the largest historical eruption of South America in 1600 CE. It has no prominent topographic expression and lies within a 2.5-km-wide collapse depression and further excavated by glaciers within a Tertiary to Pleistocene edifice. Three overlapping ash cones with craters up to 100 m deep were constructed during the 1600 CE eruption on the floor of the older crater, whose outer flanks are heavily mantled by ash deposits from the 1600 eruption. This powerful fissure-fed eruption may have produced nearly 30 km3 of dacitic tephra, including pyroclastic flows and surges that traveled 13 km to the E and SE. Lahars reached the Pacific Ocean, 120 km away. The eruption caused substantial damage to the major cities of Arequipa and Moquengua.

Lewotolok, Lembata Island

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

PVMBG reported that the eruption at Lewotolok continued during 6-10 March. White-and-gray ash plumes rose 100-600 m above the summit and drifted W, E, and SE on 6 March. The next day white, gray, and black ash plumes rose 100-800 m above the summit and drifted E and SE. White emissions rose 100-300 m and drifted E and SE on 8 March; no emissions were visible during 9-10 March. According to a news report the lava flows on the S and SE flanks were 600 m and 1.8 km long, respectively, as of 7 March and had not advanced. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 2 km away from the vent and 3 km away from the vent on the S and SE flank.

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.

Marapi, Central Sumatra

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

PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 6-12 March. White-and-gray ash plumes rose 250-700 m above the summit and drifted in multiple directions during 6-8 March. White steam-and-gas plumes rose 150-250 m above the summit and drifted NE, E, and SE during 9-12 March. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 4.5 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 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide 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 reported in historical time.

Merapi, Central Java

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

BPPTKG reported that the eruption at Merapi (on Java) continued during 1-7 March. Seismicity remained at high levels. The SW lava dome produced 123 lava avalanches that descended the S and SW flanks; one traveled S as far as 1 km down the upper part of the Boyong drainage and 122 traveled SW as far as 2 km down the upper part of the Bebeng drainage. A series of eight pyroclastic flows traveled as far as 2.6 km down the SW flank on 4 March; ashfall was reported at the Pasarbubar station, 800 m N, and minor ashfall was reported in Selo (6 km NNW) and Cepogo (4 km NE). Morphological changes to the SW lava dome identified in webcam images were due to continuing effusion and collapses of material. 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.

Nevado del Ruiz, Colombia

4.892°N, 75.324°W | Summit elev. 5279 m

Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that eruptive activity at Nevado del Ruiz continued at moderate levels during 5-11 March. Seismic events indicating rock fracturing increased both in number and intensity compared to the previous week. These events were located in areas up to 13 km NW, SSW, and NE from Arenas Crater at depths of 1-10 km. The largest earthquake, a M 1.8, was recorded at 1108 on 7 March and was located 4 km SSW of the crater at a depth of 4 km. Seismicity associated with fluid movement in the conduit decreased in both number and magnitude. These events were mainly associated with ash-and-gas emissions that rose as high as 1.1 km above the summit and up to 2 km as the plume drifted downwind. Several thermal anomalies on the crater floor were identified in satellite data, though they had low-to-moderate values. The Alert Level remained at Yellow (the second level on a four-level scale), and the public was warned to stay out of the restricted areas around Arenas Crater.

Geological summary: Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America’s deadliest eruption.

Poas, Costa Rica

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

OVSICORI-UNA reported that about 900 small phreatic eruptions at Poás were recorded by the seismic network and often visually observed during 4 March to around 0800 on 8 March; no additional eruptions were recorded at least through 12 March. The small eruptive events ejected material no higher than 50 m. The water at the bottom of the crater had almost disappeared leaving a couple of muddy water puddles. Boca C remained underwater and frequently bubbled. Weak incandescence from sulfur combustion at Boca A (SW part of crater floor) was frequently observed at night. Gas-and-steam emissions rose from the vents and caused a sulfur odor in the vicinity of the volcano during the earlier part of the week.

Geological summary: The broad vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S 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 N-S-trending fissure cutting the complex stratovolcano extends to the lower N 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 of 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.

Popocatepetl, Mexico

19.023°N, 98.622°W | Summit elev. 5393 m

CENAPRED reported that eruptive activity continued at Popocatépetl during 5-12 March. The seismic network recorded daily periods of high-frequency, low-amplitude tremor that lasted from about 17 hours to almost 24 hours. The Washington VAAC reported that daily ash plumes visible in webcam and satellite images generally rose to 5.8-7.3 km (19,000-24,000 ft) a.s.l. and drifted predominantly N, NE, and E. The ash emissions were continuous for periods of time with remnant ash often visible in subsequent satellite images, drifting almost 900 km before dissipating; on 9 March plumes were identified drifting across the southern Gulf of Mexico.

Several municipalities in Puebla reported ashfall on 7 March and operations at the Aeropuerto Internacional Hermanos Serdán in Puebla were suspended at 0700 so that the runways could be cleared of ashfall. At 1351 on 8 March and at 1650 on 9 March gas-and-steam plumes with low ash content rose 1.2 and 1.6 km above the crater rim, respectively, and drifted NE. Several municipalities in Puebla again reported ashfall during 10-11 March; municipalities in Tlaxcala reported ashfall on 11 March. The airport again suspended operations at 0700 on 11 and 12 March so that the runways could be cleared of ashfall.

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

Santa Maria, Southwestern Guatemala

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

INSIVUMEH reported that eruptive activity continued at Santa Maria’s Santiaguito lava dome complex during 6-12 March with a lava extrusion and avalanches at the Caliente dome. Incandescence from the dome was visible during most nights and early mornings, and occasional incandescence was also present along the upper part of the lava flow on the WSW flank. Daily explosions generated gas-and-ash plumes that rose 600-900 m above the summit and drifted NW, W, SW, and S; the explosions occurred at a rate of 1-8 per hour on at least a few of the days where reported. The explosions produced block avalanches on the dome’s flanks and generated occasional, short-range pyroclastic flows that mainly descended the W, S, and E flanks. Block avalanches from the dome and the margins of the upper part of the lava flow were also sometimes visible. Rumblings were heard occasionally. Ashfall was reported in Belén (10 km S), Calaguache (9 km S), and Las Marías (10 km S) during 5-6 March and in San Marcos Palajunoj (8 km SW), Loma Linda (7 km W), and other nearby communities during 6-7 and 10-12 March; ash caused hazy conditions around the volcano during 8-9 March.

Geological summary: Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank, and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four vents, with activity progressing E towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.

Semeru, Eastern Java

8.108°S, 112.922°E | Summit elev. 3657 m

PVMBG reported that eruptive activity continued at Semeru during 6-12 March. Gray-and-white ash plumes, that were often dense, rose 500-1,000 m above the summit and drifted in multiple directions on most of the days; eruptive events were detected on 10 March but plumes were not observed. The Alert Level remained at 3 (the third highest level on a scale of 1-4). The public was warned to stay at least 5 km away from the summit in all directions, 13 km from the summit to the SE, 500 m from the banks of the Kobokan drainage as far as 17 km 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 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, Central Kamchatka (Russia)

56.653°N, 161.36°E | Summit elev. 3283 m

KVERT reported that eruptive activity at Sheveluch continued during 29 February-6 March with a daily thermal anomaly identified in satellite images. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka’s largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

Stromboli, Aeolian Islands (Italy)

38.789°N, 15.213°E | Summit elev. 924 m

INGV reported that eruptive activity continued at Stromboli during 4-10 March. Webcam images showed Strombolian activity at two vents in Area N (one at N1 and one at N2), within the upper part of the Sciara del Fuoco, and from two vents at S2 in Area C-S (South-Central Crater) in the crater terrace. At Area N, low-intensity explosive activity was observed from sectors N1 and N2 with the eruption of coarse material (bombs and lapilli) as high as 80 and 150 m above the vents, respectively. The average frequency of explosions from this area was 3-5 events per hour. At Area C-S, explosive activity was observed from sector S2 with the ejection of coarse and fine material (bombs, lapilli, and ash) as high as 150 m above the vent. The average explosions rate was 5-10 events per hour.

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

Suwanosejima, Ryukyu Islands (Japan)

29.638°N, 129.714°E | Summit elev. 796 m

JMA reported that the eruption at Suwanosejima’s Ontake Crater continued during 4-11 March. Crater incandescence was observed in webcam images nightly and large blocks were sometimes ejected up to 400 m from the vent. An eruptive event at 0905 on 4 March generated an ash plume that rose straight up as high as 1.3 km above the crater rim. Explosions recorded at 1256 on 6 March, 1002 on 7 March, 1746 on 8 March, and 2333 on 9 March generated ash plumes that rose as high as 900 m before sometimes merging into weather clouds; plumes drifted S and SE. An explosion was recorded at 0138 on 7 March, though emission details were unknown. The Alert Level remained at 2 (on a 5-level scale) and the public was warned to stay at least 1 km away from 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.

Ubinas, Peru

16.345°S, 70.8972°W | Summit elev. 5608 m

Instituto Geofísico del Perú (IGP) reported that a lahar on the SE flank of Ubinas descended through the Volcánmayo drainage towards the Ubinas River at 1445 on 6 March. The public was warned to stay away from the drainage and to avoid driving on the Querapi-Ubinas-Huarina highway.

Geological summary: The truncated appearance of Ubinas, Perú’s most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.

Yasur, Vanuatu

19.532°S, 169.447°E | Summit elev. 361 m

On 8 March 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). Recent visual observations and photos taken in the field indicated that explosions continued, though activity was confined to the crater. The report warned that some of the explosions may eject material that falls in and around the crater. 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 – March 6- 12, 2024 – Managing Editor: Sally Sennert.

Featured image credit: TW

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