This report covers active volcanoes recorded from May 16 – May 22, 2012 based on Smithsonian/USGS criteria. New unrest has been noticed around 2 volcanoes, ongoing activity was reported for 10 volcanoes.
14.473°N, 90.880°W; summit elev. 3763 m
On 19 May seismicity at Fuego increased and explosions were heard at 5-10 minute intervals. A 600-m-long lavaflow descended the W flank, and a 1-km-long and 20-m-wide lava flow descended the E flank, reaching the base of the volcano. Explosions ejected incandescent tephra 400 m above the crater, and produced ash plumes that rose 5 km above the crater and drifted 30 km S and SW. Coordinadora Nacional para la Reducción de Desastres (CONRED) raised the Alert Level to Orange (the second highest level on a 4-color scale). Pyroclastic flows also descended the flanks, prompting authorities to restrict passage on part of a highway. Ash plumes from thepyroclastic flows rose 3 km above the crater. Ashfall was reported in Morelia (7 km SW), Panimaché I and II (9 km SW), Sangre de Cristo (8 km WSW), and Yepocapa (8 km WNW). Thirteen people from El Porvenir in Alotenango (8 km ENE) evacuated to local shelters. Visual observations and seismicity indicated that activity decreased later that day.
On 20 May a few explosions generated ash plumes that rose 500 m above the crater and drifted 8 km SW. The next day cloud cover prevented observations; however explosions, rumbling, and degassing sounds were reported. On 22 May explosions generated ash plumes that rose as high as 1 km and drifted 10 km S and SE. Rumbling was heard and shock waves were detected. The lava flows were inactive and only incandescence from block avalanches was observed.
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.
MARAPI, Sumatra (Indonesia)
0.381°S, 100.473°E; summit elev. 2891 m
According to a news article, an approximately 10-minute-long eruption from Marapi produced an ash plume that rose 600 m on 18 May. The article noted that the Alert Level remained at 2 (on a scale of 1-4).
Geologic summary: Gunung Marapi, not to be confused with the better known Merapi volcano on Java, is Sumatra’s most active volcano. Marapi is a massive complex stratovolcano that rises 2,000 m above the Bukittinggi plain in Sumatra’s 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, along which volcanism has migrated to the W. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no historical lava flows outside the summit craters have been reported.
BATU TARA, Komba Island (Indonesia)
7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 18 and 20-21 May ash plumes from Batu Tara rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted 27-55 km N and NW.
Geologic summary: The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy’s Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historicaleruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
CLEVELAND, Chuginadak Island
52.825°N, 169.944°W; summit elev. 1730 m
AVO reported that during 16-22 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 18 May an ash plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 55 km E.
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 11-18 May, and indicated that possible ash plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. on 10 and 14 May. Satellite imagery showed a thermal anomaly on the volcano during 10-13 and 16 May. The Aviation Color Code remained at Orange.
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 16-22 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, and spilled over the deep inner ledge on multiple occasions. On 15 May laser measurements indicated that the lava-lake surface was about 65 m below the Halema’uma’u Crater floor, among the highest levels measured; the lake rose five more meters during 18-19 May. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash, and occasionally freshspatter from the margins of the lava lake, onto nearby areas. A lava pond in a small pit on the E edge of Pu’u ‘O’o crater floor remained active with spattering. On 19 May a small collapse of the N rim of the pit slightly enlarged the pit and lava pond within. A small lava flow erupted from a vent on the S part of the floor. Lava flows were active on the pali and the coastal plain, and were about 750 m from the sea.
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, although cloud cover often prevented observations of Popocatépetl during 16-22 May, multiple gas-and-ash plumes were observed daily rising as high as 1.5 km above crater. Plumes drifted NW, NE, SE, and SW. Incandescent fragments ejected from the crater landed on the flanks as far as 800 m away. Seismicity remained high. 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
Based on information from JMA, the Tokyo VAAC reported that during 16-20 and 22 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted multiple directions. Pilots observed ash plumes during 16-17 May that rose to altitudes of 2.7-4 km (9,000-13,000 ft) a.s.l. and drifted E and SE. Explosions were detected during 21-22 May.
JMA reported that during 18-21 May explosive eruptions from Showa Crater occurred multiple times and ejectedtephra as far as 1.8 km from the crater. Incandescence from the crater was observed at night. Very small eruptions from Minami-dake Crater occurred on 18 and 19 May, and a small pyroclastic flow traveled 300 m down the Showa crater flanks on 21 May.
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.
SANTA MARIA, Guatemala
14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that on 21 May a lahar traveled down Santa María’s Rio Nima II drainage, carrying tree branches and 40-cm-wide lava blocks. On 22 May explosions produced ash plumes that rose 900 m above Caliente dome and drifted 10 km SE. Ashfall was reported in San Felipe (15 km SSW), El Nuevo Palmar (12 km SSW), and areas on the E flank.
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 explosive activity at Shiveluch continued during 11-18 May. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the active crater, and was accompanied byfumarolic activity and lava-dome incandescence. Satellite imagery during 10-12 and 15-16 May showed a thermal anomaly on the lava dome. On 12 May observers reported that ash plumes rose to an altitude of 8 km (26,200 ft)a.s.l. and satellite imagery showed an ash plume drifting more than 800 km E.
Based on information from KVERT and analyses of satellite images, the Tokyo VAAC reported that on 20 May anash plume rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted SW. Images the next day showed that the ash had dissipated.
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 16-22 May visual observations of Tungurahua were often limited due to cloud cover. On 16 May a steam-and-gas plume drifted W and lahars descended the W flank. On 18 May ashfall was reported in Manzano (8 km SW), Choglontus (SW), Chontapamba (W), Yuibug, Puela (8 km SW), and high in the Mapayacu drainage (SW). Roaring was heard on 22 May, and slight ashfall was reported in Manzano.
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
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