This report covers active volcanoes recorded from May 23 – May 29, 2012 based on Smithsonian/USGS criteria. New unrest has been noticed around 5 volcanoes, ongoing activity was reported for 11 volcanoes.
14.473°N, 90.880°W; summit elev. 3763 m
INSIVUMEH reported that during 22-23 May explosions from Fuego produced ash plumes that rose 700 m above the crater and drifted W and SW. Explosions produced shock waves and rumbling noises, and avalanches descended the SW flank towards the Ceniza drainage. Seismic data suggested that on 25 May lava was emitted in the crater, although lava flows were not observed the previous few days. Plumes rose 2 km above the crater and drifted SE, SW, and W. Ashfall was reported in Sangre de Cristo (8 km WSW), Yepocapa (8 km WNW), and in the department of Chimaltenango (21 km NNE). A pyroclastic flow traveled SW down the Las Lajas drainage. During 26-29 May explosions produced ash plumes that rose as high as 1 km above the crater and drifted N, NE, S, and SE. A lava flow traveled 200 m SW and avalanches from the lava-flow front traveled 300 m during 26-27 May. Pulses of incandescence 100 m high were observed during 28-29 May.
Geologic summary: Volcán Fuego, one of Central America's most active volcanoes, is one of three largestratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
GALUNGGUNG, Western Java (Indonesia)
7.25°S, 108.058°E; summit elev. 2168 m
CVGHM reported that, since the Alert Level was raised on 12 February, seismic activity at Galunggung had drastically decreased through 27 May. During 27 April-27 May plants around the crater area looked green and lush, small fish were swimming in the water, and insects around the crater were active. Based on seismic data, crater lake water temperature and pH data, and visual observations, CVGHM lowered the Alert Level from 2 to 1 (on a scale of 1-4) on 28 May.
Geologic summary: The forested slopes of 2,168-m-high Galunggung volcano in western Java are cut by a large horseshoe-shaped caldera breached to the SE that has served to channel the products of recent eruptions in that direction. The "Ten Thousand Hills of Tasikmalaya" dotting the plain below the volcano are debris-avalanche hummocks from the collapse that formed the breached caldera about 4,200 years ago. Although historicaleruptions, restricted to the central vent near the caldera headwall, have been infrequent, they have caused much devastation. The first historical eruption in 1822 produced pyroclastic flows and lahars that killed over 4,000 persons. More recently, a strong explosive eruption during 1982-1983 caused severe economic disruption to populated areas near the volcano.
NEVADO DEL RUIZ, Colombia
4.895°N, 75.322°W; summit elev. 5321 m
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that on 22 May a seismic signal possibly indicated an ash emission from Nevado del Ruiz, though it was not confirmed due to poor weather conditions. On 29 May activity significantly increased; at 0307 seismic signals indicated ash emissions that were confirmed by officials and residents near the volcano as well as with a web camera. The Alert Level was raised to II (Orange; "eruption likely within days or weeks"). A gas-and-ash plume rose 1 km above the crater and ashfall was reported in Anserma (65 km NW), Aranzazu (45 km NNW), Chinchiná (30 km WNW), Dosquebradas (40 km W), Filadelfia, La Merced (60 km NNW), Manizales (30 km NW), Marmato (70 km NNW), Neira (37 km NW), Palestina (40 km WNW), Pereira (40 km WSW), Risaralda (78 km WNW), Salamina (60 km NNW), San José (56 km NW), Santagueda (40 km NW), Santa Rosa de Cabal (33 km W), Supia (72 km NNW), Villamaria (28 km NW), and Viterbo (65 km WNW). Ash also fell in all municipalities in the department of Risaralda (76 km WNW) and El Aguila (85 km W, N of Valle del Cauca). Sulfur dioxide plumes were detected by satellite and a sulfur dioxide odor was reported in multiple towns. Later that day ash emissions rose 600 m above the crater.
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 summit caldera of an older Ruiz volcano. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. Steep headwalls of massive landslides cut the flanks of Nevado del Ruiz. 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.
SIRUNG, Pantar Island (Indonesia)
8.508°S, 124.13°E; summit elev. 862 m
CVGHM reported that during 13-18 May diffuse white plumes from Sirung rose 10-50 m above the crater. Seismicity was elevated during 12-17 May then decreased through 23 May, although levels remained above background. On 25 May the Alert Level was lowered to 2 (on a scale of 1-4).
Geologic summary: Sirung volcano is located at the NE end of a 14-km-long line of volcanic centers that form a peninsula at the southern end of Pantar Island. The low, 862-m-high volcano is truncated by a 2-km-wide calderawhose floor often contains one or more small lakes. Much of the volcano is constructed of basaltic lava flows, and the Gunung Sirung lava dome forms the high point on the caldera's western rim. A number of phreatic eruptions have occurred from vents within the caldera during the 20th century.
1.108°N, 124.73°E; summit elev. 1784 m
CVGHM reported that observers in the village of Maliku noted that during 21-27 May white plumes rose 50-150 m above the crater of Soputan. Seismicity increased significantly on 25 May. CVGHM raised the Alert Level to 3 (on a scale of 1-4) on 28 May based on visual observations and increased seismicity.
Geologic summary: The small conical volcano of Soputan on the southern rim of the Quaternary Tondano calderais one of Sulawesi's most active volcanoes. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.
6.140°S, 155.195°E; summit elev. 1750 m
According to NASA's Earth Observatory, a satellite image of Bagana acquired on 16 May showed a lava flow on the E flank. Other satellite images indicated that the lava flow was emplaced sometime between March 2011 and February 2012. A plume drifted W.
Geologic summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is 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 volcano's flanks on all sides.
CLEVELAND, Chuginadak Island
52.825°N, 169.944°W; summit elev. 1730 m
AVO reported that during 23-29 May satellite observations of Cleveland's summit crater revealed nothing unusual; no ash emissions or other signs of unrest were detected or reported. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Geologic summary: Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 25 May an ash plume from Dukono rose to an altitude of 4.5 km (14,000 ft) a.s.l. and drifted 185 km E. Ash plumes again rose to an altitude of 4.5 km (14,000 ft) a.s.l. drifting 130 km E on 27 May and 93 km NE on 28 May. An ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 75 km NE during 28-29 May.
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 N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that moderate seismic activity from Karymsky continued to be detected during 18-25 May, and indicated that possible ash plumes rose to an altitude of 2.2 km (7,200 ft) a.s.l. on 17 and 19 May. Satellite imagery showed a thermal anomaly on the volcano during 17-18, 20, 22, and 24 May. The Aviation Color Code remained at Orange.
Based on information from the Yelizovo Airport (UHPP) and analyses of satellite imagery, the Tokyo VAAC reported that on 27 May an ash plume drifted NE at an altitude of 3 km (10,000 ft) a.s.l.
Geologic summary: Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetricalstratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky 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. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
KILAUEA, Hawaii (USA)
19.421°N, 155.287°W; summit elev. 1222 m
During 23-29 May HVO reported that the circulating and spattering lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Parts of the inner ledge and crater wall surrounding the lake occasionally collapsed into the lake. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash, Pele's hair, and occasionally fresh spatter from the margins of the lava lake, onto nearby areas. The level of the lava pond in a small pit on the E edge of Pu'u 'O'o crater floor dropped out of view. A small lava flow erupted from a vent on the S part of the floor on 23 May. On 28 May HVO noted that lava-flow activity on the coastal plain SE of Pu'u 'O'o appeared to have stopped.
Geologic summary: Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 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.
19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 23-29 May gas-and-ash plumes from Popocatépetl rose up to 2 km above the crater and drifted in multiple directions. Cloud cover occasionally prevented observations of the plumes. Ashfall was reported in San Pedro Benito Juarez (10-12 km SE) and Huejotzingo (27 km NE) on 23 May, and in Atlixco (23 km SE) and San Pedro Benito Juarez on 25 May. Incandescent fragments ejected from the crater landed on the flanks during 23-26 May. Incandescence from the crater was visible on 27 May. The Alert Level remained at Yellow Phase Three.
Geologic summary: Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported eight explosive eruptions from Sakura-jima's Showa Crater during 21-25 May and a small eruption from Minami-dake Crater on 23 May. Based on information from JMA, the Tokyo VAAC reported that during 23-24 and 26-28 May explosions produced plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted SW, S, SE, E, and NE.
Geologic summary: Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira calderaat the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have depositedash 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.
2.002°S, 78.341°W; summit elev. 5230 m
Based on a SIGMET report, the Washington VAAC reported a possible eruption and ash plume from Sangay on 28 May. A later notice stated that a pilot reported an ash plume at an altitude of 6.1 km (20,000 ft) a.s.l. Ash was not identified in satellite imagery.
Geologic summary: The isolated Sangay volcano, located E of the Andean crest, is the southernmost of Ecuador's volcanoes, and its most active. It has been in frequent eruption for the past several centuries. The steep-sided, 5,230-m-high glacier-covered volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the E, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. Sangay towers above the tropical jungle on the E side; on the other sides flat plains of ash from the volcano have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of an historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The more or less constant eruptive activity has caused frequent changes to the morphology of the summit crater complex.
SANTA MARIA, Guatemala
14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that during 22-23 and 28-29 May explosions from Santa María's Santiaguito lava-domecomplex produced ash plumes that rose 400-900 m above Caliente dome and drifted E, SE, and S. During 26-27 May explosions produced ash plumes that drifted W. Avalanches were generated by the W part of the lava domeand from lava flows. On 29 May lahars traveled S down the Rio Nima I and San Isidro drainages, carrying tree branches and blocks 1-1.5 m in diameter.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoesthat rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large 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 westward-younging vents, accompanied by almost continuous minor explosions and periodiclava extrusion, larger explosions, pyroclastic flows, and lahars.
SHIVELUCH, Central Kamchatka (Russia)
56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 18-25 May explosive activity at Shiveluch continued and a thermal anomaly was observed daily in satellite imagery. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the active crater, and was accompanied by fumarolic activity and lava-dome incandescence. On 19 May seismic data indicated that possible ash plumes rose to an altitude of 9.5 km (31,200 ft) a.s.l. On 20 May observers noted ash plumes rising to altitudes of 8-9 km (26,200-29,500 ft) a.s.l.; satellite images showed ash plumes drifting 410 km SW. The Aviation Color Code remained at Orange.
Based on information from KVERT and KEMSD, and analyses of satellite images, the Tokyo VAAC reported that during 26-29 May ash plumes from eruptions and possible eruptions rose to altitudes of 7-9.1 km (23,000-30,000 ft)a.s.l. and drifted SE, W, and SW.
Geologic summary: The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
1.467°S, 78.442°W; summit elev. 5023 m
IG reported that during 23-24 May gas-and-ash plumes from Tungurahua drifted SW, W, and NW. Ashfall was reported in Mapayacu (SW), Puela (8 km SW), Manzano (8 km SW), Cahuají (8 km SW), and Riobamba (30 km S). An explosion detected on 25 May was accompanied by roaring and sounds resembling rolling blocks. An ash plume rose 2.5 km above the crater and drifted NW. A steam-and-gas plume rose 200 m and drifted W. Cloud cover prevented observations during 26-29 May. Ashfall was reported in Manzano and Choglontus (SW) on 29 May.
Geologic summary: The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes bypyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.
Source: Global Volcanism Program
Featured image: Santiaguito on May 31, 2012 INSIVUMEH