Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)
URL: http://www.volcano.si.
New Activity/Unrest: Aira, Kyushu (Japan) | Bezymianny, Central Kamchatka (Russia) | Cerro Azul, Isla Isabela (Ecuador) | Chirinkotan, Kuril Islands (Russia) | Kambalny, Southern Kamchatka (Russia) | Manam, Papua New Guinea | Nevados de Chillan, Chile
Ongoing Activity: Bagana, Bougainville (Papua New Guinea) | Bogoslof, Fox Islands (USA) | Cleveland, Chuginadak Island (USA) | Colima, Mexico | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Nevado del Ruiz, Colombia | Pacaya, Guatemala | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Suwanosejima, Ryukyu Islands (Japan) | Turrialba, Costa Rica
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.
New Activity/Unrest
Aira | Kyushu (Japan) | 31.593°N, 130.657°E | Summit elev. 1117 m
JMA reported that an explosion at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) detected at 1803 on 25 March generated a pyroclastic flow that traveled 1.1 km down the S flank. An explosion at 2228 produced an ash plume that rose 1.4 km above the crater rim. Ash fell in the vicinity of the volcano and as far as 4.5 km E. Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that ash plumes drifted SE and E that same day.
Geologic 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 Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.
Sources: Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.
Japan Meteorological Agency (JMA) http://www.jma.go.jp/
Bezymianny | Central Kamchatka (Russia) | 55.972°N, 160.595°E | Summit elev. 2882 m
KVERT reported that during 17-24 March lava continued to advance down the NW flank of Bezymianny's lava dome. A thermal anomaly was visible in satellite images on 17, 19, and 22 March. The Aviation Color Code remained at Orange.
Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Cerro Azul | Isla Isabela (Ecuador) | 0.92°S, 91.408°W | Summit elev. 1640 m
IG reported that increased seismicity at Cerro Azul began on 15 February and was characterized by the presence of volcano-tectonic events. A 1-hour-long swarm occurred the next day, and then afterwards only sporadic events were detected, some of which were located in the Sierra Negra volcano region. Sporadic events located at Sierra Negra continued to be detected during 8-13 March. A 30-minute-long swarm was recorded on 18 March. Earthquakes became more frequent and intense on 19 March, and another swarm occurred during 0700-1800 on 20 March; earthquake locations migrated SW, to the SE part of Cerro Azul during 19-20 March. Another swarm was detected during 1915-2200 on 21 March, with most magnitudes between 2.4 and 3, though the highest was 3.6.
Deformation during 8-20 March was detected in satellite data, characterized by 14 cm of inflation at the SE flank and 11.2 cm of deflation at the summit. Deformation and seismic data suggested the emplacement of a sill 3.5-6.3 km below the SE flank.
Geologic Summary. Located at the SW tip of the J-shaped Isabela Island, Cerro Azul contains a steep-walled 4 x 5 km nested summit caldera complex that is one of the smallest diameter, but at 650 m one of the deepest in the Galápagos Islands. The 1640-m-high shield volcano is the second highest of the archipelago. A conspicuous bench occupies the SW and west sides of the caldera, which formed during several episodes of collapse. Youthful lava flows cover much of the caldera floor, which has also contained ephemeral lakes. A prominent tuff cone located at the ENE side of the caldera is evidence of episodic hydrovolcanism. Numerous spatter cones dot the western flanks. Fresh-looking lava flows, many erupted from circumferential fissures, descend the NE and NW flanks. Historical eruptions date back only to 1932, but Cerro Azul has been one of the most active Galápagos volcanoes since that time. Solfataric activity continues within the caldera.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
Chirinkotan | Kuril Islands (Russia) | 48.98°N, 153.48°E | Summit elev. 724 m
SVERT noted that no further activity at Chirinkotan was visible after the ash emission on 21 March. The Aviation Color Code was lowered to Green (on a four-color scale).
Geologic Summary. The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.
Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/?
Kambalny | Southern Kamchatka (Russia) | 51.306°N, 156.875°E | Summit elev. 2116 m
KVERT reported that the onset of an eruption at Kambalny, witnessed by staff at the Kronotsky State Nature Reserve, began at 0950 on 25 March. Satellite data showed an ash plume drifting 35 km SW at altitudes of 5-6 km (16,400-19,700 ft) a.s.l. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale). The eruption intensified later that day, with ash plumes rising as high as 7 km (23,000 ft) a.s.l. and drifting as far as 255 km SSW. Ash plumes continued to be generated at least through 28 March, varying in altitude from 3.5-6 km (11,500-19,700 ft) a.s.l. and drifting as far as 1,350 km SSW, S, SSE, and SE during 26-27 March, and 51 km W on 28 March.
Geologic Summary. The southernmost major stratovolcano on the Kamchatka peninsula, Kambalny has a summit crater that is breached to the SE. Five Holocene cinder cones on the W and SE flanks have produced fresh-looking lava flows. Beginning about 6,300 radiocarbon years ago, a series of major collapses of the edifice produced at least three debris-avalanche deposits. The last major eruption took place about 600 years ago, although younger tephra layers have been found, and an eruption was reported in 1767. Active fumarolic areas are found on the flanks of the volcano, which is located south of the massive Pauzhetka volcano-tectonic depression.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Kronotsky State Nature Reserve http://www.kronoki.ru/
Manam | Papua New Guinea | 4.08°S, 145.037°E | Summit elev. 1807 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 24 March a steam plume from Manam, possibly with a minor ash content, drifted 75 km SE.
Geologic 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 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche 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 historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical 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.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Nevados de Chillan | Chile | 36.863°S, 71.377°W | Summit elev. 3212 m
On 24 March OVDAS-SERNAGEOMIN reported that during an overflight of Nevados de Chillán scientists observed a single 100-m-diameter crater, the result of two active craters merging together sometime between 7 and 15 March. In addition there were five explosions in the period of about an hour, ejecting tephra 900 m high which dispersed SE. The pattern of activity changed on 17 March with increased frequency and magnitude of the explosions. The Alert Level remained at Yellow, the middle level on a three-color scale, and the public was reminded not to approach the craters within a 3-km radius.
Geologic 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 largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.
Ongoing Activity
Bagana | Bougainville (Papua New Guinea) | 6.137°S, 155.196°E | Summit elev. 1855 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 27-28 March a minor ash plume from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 110 km SW and W.
Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Bogoslof | Fox Islands (USA) | 53.93°N, 168.03°W | Summit elev. 150 m
AVO reported that no significant volcanic activity at Bogoslof was detected in seismic or infrasound data during 22-28 March, and satellite views were often obscured by clouds or showed nothing noteworthy. Weakly elevated surface temperatures were identified in satellite images during 21-23 March. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Warning.
Geologic Summary. Bogoslof is the emergent summit of a submarine volcano that lies 40 km north of the main Aleutian arc. It rises 1500 m above the Bering Sea floor. Repeated construction and destruction of lava domes at different locations during historical time has greatly modified the appearance of this "Jack-in-the-Box" volcano and has introduced a confusing nomenclature applied during frequent visits of exploring expeditions. The present triangular-shaped, 0.75 x 2 km island consists of remnants of lava domes emplaced from 1796 to 1992. Castle Rock (Old Bogoslof) is a steep-sided pinnacle that is a remnant of a spine from the 1796 eruption. Fire Island (New Bogoslof), a small island located about 600 m NW of Bogoslof Island, is a remnant of a lava dome that was formed in 1883.
Source: US Geological Survey Alaska Volcano Observatory (AVO) http://www.avo.alaska.
Cleveland | Chuginadak Island (USA) | 52.825°N, 169.944°W | Summit elev. 1730 m
A small explosion at Cleveland was detected in both seismic and infrasound data at 0815 on 24 March, prompting AVO to raise the Aviation Color Code to Orange and the Volcano Alert Level to Watch. Cloud cover at 9.1 km (30,000 ft) a.s.l. obscured satellite observations of the volcano, and no ash cloud was observed from this event. Cloud cover prevented views during 25-27 March, and slightly elevated surface temperatures were identified in satellite data during 27-28 March; nothing significant was detected in seismic or infrasound data.
Geologic Summary. Beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited, dumbbell-shaped Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Cleveland is joined to the rest of Chuginadak Island by a low isthmus. The 1730-m-high Mount Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name for Mount Cleveland, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
Source: US Geological Survey Alaska Volcano Observatory (AVO) http://www.avo.alaska.
Colima | Mexico | 19.514°N, 103.62°W | Summit elev. 3850 m
On 24 March the Centro Universitario de Estudios e Investigaciones de Vulcanologia - Universidad de Colima reported that during the previous week the seismic data revealed 70 high-frequency events, 25 long-period events, over one hour of tremor, four landslides, and four low-intensity explosions. The sulfur dioxide flux was 11-74 tons/day, reflecting low volcanic activity.
Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.
Source: Centro Universitario de Estudios e Investigaciones de Vulcanologia - Universidad de Colima http://portal.ucol.mx/
Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m
Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 22-28 March ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted in multiple directions.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Ebeko | Paramushir Island (Russia) | 50.686°N, 156.014°E | Summit elev. 1103 m
KVERT reported that during 20-22 March several explosions at Ebeko, observed by residents of Severo-Kurilsk (Paramushir Island) about 7 km E, generated plumes that rose to altitudes of 1.7-1.8 km (5,600-5,900 ft) a.s.l. Minor amounts of ash fell in Severo-Kurilsk on 21 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Geologic 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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Fuego | Guatemala | 14.473°N, 90.88°W | Summit elev. 3763 m
INSIVUMEH reported that during 25-28 March explosions at Fuego generated ash plumes that rose as high as 1.1 km above the crater rim and drifted 10-12 km SW and S. Ashfall was reported in areas downwind including Panimaché I and II (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), Los Yucales, and El Porvenir. Shock waves and rumbling from the explosions were sometimes heard; structures in local areas were rattled from explosions during 26-27 March. Incandescent material was ejected as high as 300 m above the crater rim, and sometimes landed 250 m away. Avalanches of material were confined to the crater. INSIVUMEH noted that activity had become more intense on 27 March.
Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. 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 Acatenango. In contrast to 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.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
During 22-28 March HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. A small collapse of the S part of the crater wall at 0035 on 23 March was followed by a short time of increased spatter.
Webcams recorded incandescence from long-active sources within Pu'u 'O'o Crater, from a vent high on the NE flank of the cone, and from a small lava pond in a pit on the W side of the crater. The 61G lava flow, originating from a vent on Pu'u 'O'o Crater's E flank, continued to enter the ocean at Kamokuna from the end of the lava tube, about 20 m above the water; the ocean entry was not consistently visible during the week. Surface lava flows were active above the pali, with most of the activity located 1.9-2.9 km from the 61G vent. During 24-25 March HVO noted that a delta had begun to form at the ocean entry, for the first time since the previous one had collapsed on 31 December 2016.
Geologic Summary. Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m
On 24 March KVERT reported that gas-and-steam emissions continued to rise from Klyuchevskoy's crater, and a weak thermal anomaly was occasionally identified in satellite images. The Aviation Color Code was lowered to Green (the lowest level on a four-color scale). On 28 March a gas, steam, and ash plume identified in satellite data rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. and drifted 108 km ENE. The Aviation Color Code was raised to Yellow. The next day an ash plume rose as high as 7.5 km (24,600 ft) a.s.l. and drifted 75 km SW. The Aviation Color Code was raised to Orange.
Geologic Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Nevado del Ruiz | Colombia | 4.892°N, 75.324°W | Summit elev. 5279 m
Based on info from Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales, the Washington VAAC reported that on 26 March ash plumes from Nevado del Ruiz rose to an altitude of 7 km (23,000 ft) a.s.l. On 27 March the observatory reported that at 1029 a gas-and-ash plume rose 1.6 km above the crater rim and drifted E. The emission was associated with a seismic event and was also recorded by a webcam.
Geologic Summary. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. 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.
Sources: Servicio Geológico Colombiano (SGC) http://www.ingeominas.
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.
Pacaya | Guatemala | 14.381°N, 90.601°W | Summit elev. 2552 m
In a special report from 24 March INSIVUMEH noted that lava fountains 25-50 m high rose from a new cone forming in the crater of Pacaya’s Mackenney’s cone. The accumulated material had been filling up the cone, causing lava to flow through the crater breach formed in 2010. During 25-28 March small Strombolian explosions ejected material as high as 30 m above the cone.
Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.
Sabancaya | Peru | 15.787°S, 71.857°W | Summit elev. 5960 m
Based on webcam images, satellite views, and seismic data the Buenos Aires VAAC reported sporadic gas-and-ash puffs from Sabancaya during 24-27 March, sometimes rising as high as 9.1 km (30,000 ft) a.s.l. Weather clouds often hindered observations of the volcano, especially during 22-3 and 25 March.
Geologic 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 historical eruptions date back to 1750.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.smn.gov.ar/
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that during 17-24 March lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a daily thermal anomaly over the dome, and ash plumes that drifted 126 km WNW on 19 and 21 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km volcano is one of Kamchatka's largest and most active volcanic structures. 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 dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. 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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Sinabung | Indonesia | 3.17°N, 98.392°E | Summit elev. 2460 m
Based on PVMBG observations, satellite data, and wind data, the Darwin VAAC reported that during 22, 24-25, and 27 March ash plumes from Sinabung rose to altitudes of 3.3-4.3 km (11,000-14,000 ft) a.s.l. and drifted S, SE, and E.
Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Suwanosejima | Ryukyu Islands (Japan) | 29.638°N, 129.714°E | Summit elev. 796 m
Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that on 28 March an explosion at Suwanosejima generated a plume that rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted SE.
Geologic Summary. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed 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 the horseshoe-shaped Sakuchi caldera, which extends 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.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.
Turrialba | Costa Rica | 10.025°N, 83.767°W | Summit elev. 3340 m
OVSICORI-UNA reported that a weak ash emission from Turrialba was visible during 1800-1940 on 25 March. Periods of more intense crater incandescence, from possible Strombolian activity, corresponded to higher tremor amplitude during 0330-0530 on 26 March. Later that day a small plume with a minor amount of ash rose 500 m above the crater and drifted S and SE. An event at 0752 on 28 March generated an ash plume that rose 300 m and drifted S.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.
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