New unrest has been noticed around 3 volcanoes, ongoing activity was reported for 11 volcanoes. This report covers active volcanoes in the world recorded from August 1 – August 7, 2012 based on Smithsonian/USGS criteria.
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.
1.22°N, 77.37°W; summit elev. 4276 m
INGEOMINAS reported that during 31 July-6 August the magnitude and occurrence of earthquakes detected at Galeras had increased since the previous week. Gas plumes sometimes containing tephra rose from the crater. Observatory staff working near the crater reported a strong sulfur odor on 1 and 6 August. On 3 August a steam plume rose 1.1 km above the crater. On 4 August ash emissions were observed in the morning, and at 1519 a seven-minute-long episode of tremor was accompanied by a gas-and-ash plume that rose 1.4 km above the crater and drifted N. Ashfall was reported in Genoy, 6 km NE. An ash plume rose from the crater on 7 August. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
Geologic summary: Galeras, a stratovolcano with a large breached caldera located immediately W of the city of Pasto, is one of Colombia's most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Longterm extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the W and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.
TONGARIRO, North Island (New Zealand)
39.13°S, 175.642°E; summit elev. 1978 m
On 6 August GeoNet reported that volcanic earthquakes continued beneath Tongariro but the size and number had decreased; there were fewer than five events each day. At about 2350 a short-lived (~1-2 minutes) phreaticeruption occurred at the Te Mari craters area, followed by a series of discrete small earthquakes over the next few tens of minutes. The Alert Level was raised to 2 (on a scale of 0-5) and the Aviation Colour Code was raised to Orange (second highest on a four-color scale). An ash plume drifted E and ashfall was reported in areas around the volcano. According to a news article, a GNS Science volcanologist noted that there were reports of "red hot rocks being thrown out of the crater", explosions, and lighting. The article also stated that some people in the Tongariro area had self-evacuated following the eruption. The Desert Road section of State Highway 1 (NE) had been closed due to poor visibility from the ash, and about 5 cm of ash had fallen on State Highway 46, to the N. Some flights to and from Gisborne (210 km ENE), Rotorua (120 NNE), Taupo (60 km NE), and Palmerston North (135 km S) were delayed or cancelled due to the eruption, and Hawke's Bay Airport (110 km ESE) had closed. GeoNet observed that no volcanic tremor occurred in the days preceding the eruption. The last eruption occurred in 1897.
On 7 August white steam clouds rose from the Te Mari craters area but poor weather conditions at the time obscured a direct view of the active vent(s). A few small earthquakes had been detected. A news article stated that alpine guides observed three active vents that appeared to be new.
Geologic summary: Tongariro is a large andesitic volcanic massif, located immediately NE of Ruapehu volcano, that is composed of more than a dozen composite cones constructed over a period of 275,000 years. Vents along a NE-trending zone extending from Saddle Cone (below Ruapehu volcano) to Te Mari crater (including vents at the present-day location of Ngauruhoe) were active during a several hundred year long period around 10,000 years ago, producing the largest known eruptions at the Tongariro complex during the Holocene. The youngest cone of the complex, Ngauruhoe, has grown to become the highest peak of the massif since its birth about 2500 years ago. The symmetrical, steep-sided Ngauruhoe, along with its neighbor Ruapehu to the south, have been New Zealand's most active volcanoes during historical time.
WHITE ISLAND, New Zealand
37.52°S, 177.18°E; summit elev. 321 m
The GeoNet Data Centre reported that during 2011 and early 2012 White Island Crater Lake slowly evaporated, exposed steam vents, and formed two large muddy pools. Sometime between 27 July and 28 July, the lake level quickly rose 3-5 m. Vigorous gas-and-steam emissions through the new lake were observed from the air. Gas emission measurements on 1 August showed that sulfur dioxide had increased during the previous three months but carbon dioxide levels did not change.
Since early July there had been intermittent periods of volcanic tremor, including several hours early on 28 July and during 30-31 July. GeoNet noted that tremor was not uncommon at White Island but earlier in 2012 it had been at very low levels. A recent ground survey showed that the main crater floor was no longer subsiding and may have been slowly rising. The Alert Level remained at Level 1 (on a scale of 0-5), indicating signs of volcano unrest. The Aviation Colour Code increased to Yellow (second lowest on a four-color scale).
A particularly strong period of volcanic tremor was recorded during 4-5 August, and ended with an earthquake at 0454. Web camera images from between 0454 and 0457 showed an eruption from Crater Lake. This was the first time ash has been produced from White Island since 2000. The Alert Level was raised to 2 and the Aviation Colour Code was raised to Orange. A steam plume rose from the crater on 5 August. Around 2330 on 7 August volcanic tremor sharply decreased to levels detected prior to the current episode of unrest. A few hours after this drop, the color of the plume changed from white to light brown, indicating more ash in the plume. Visual observations over the past few days showed that a small cone was building in the lake around the main area of degassing.
Geologic summary: The uninhabited 2 x 2.4 km White Island, one of New Zealand's most active volcanoes, is the emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The 321-m-high island consists of two overlapping stratovolcanoes; the summit crater appears to be breached to the SE because the shoreline corresponds to the level of several notches in the SE crater wall. Throughout the short historical period beginning in 1826 the volcano has had long periods of continuous hydrothermal activity and steam release, punctuated by small-to-medium eruptions. Its activity also forms a prominent part of Maori legends. The most recent eruptive episode, which began on 7 March 2000, included the largest eruption at White Island in the past 20 years on 27 July.
6.140°S, 155.195°E; summit elev. 1750 m
Based on analyses of satellite imagery, the Darwin VAAC reported that on 2 August ash plumes from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 37 km NW and 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.
BATU TARA, Komba Island (Indonesia)
7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 1-2 and 4-7 August ash plumes from Batu Tara rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted 37-65 km NW and W.
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 historical eruption 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 cloud cover prevented satellite and web-camera observations of Cleveland during 1-3 and 5-6 August. A small explosion at 0838 on 4 August was detected based on retrospective analysis of infrasound data. Satellite images showed a brief, faint steam plume about four hours after the event and also detected elevated surface temperatures in several clear views of the volcano. On 7 August elevated surface temperatures were detected in partly-cloudy satellite images. 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.
14.473°N, 90.880°W; summit elev. 3763 m
In a special bulletin on 3 August, INSIVUMEH reported a new phase of activity at Fuego, characterized by increased seismicity and degassing sounds. Incandescent tephra was ejected 200 m high and a lava flow traveled 500 m down the SW flank into the Taniluya drainage. Pyroclastic flows likely descended the SE and SW flanks. During 4-7 August explosions produced ash plumes that rose 200-400 m above the crater and drifted NW and W. Lava flows traveled 250-300 m down the Taniluyá drainage. Detached blocks from the lava-flow front traveled down the flanks to the vegetated area. Blocks also traveled down the Ceniza drainage (SSW). At night during 5-6 August explosions ejected incandescent tephra 100 m above the crater.
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 historicaleruptions 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.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported moderate seismic activity from Karymsky during 27 July-3 August. Satellite imagery showed a weak thermal anomaly on the volcano on 31 July, and 2 and 6 August. 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 1-7 August HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Measurements indicated that the gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas. Glow from the lava pond in a small pit on the E edge of the Pu'u 'O'o crater floor and two vents along the S edge of the floor was visible with the web cameras.Lava flows were active on the pali and the coastal plain.
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.
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 during 3-6 August low levels of tremor were detected at Nevado del Ruiz, possibly associated with continuing gas andash emissions. Ashfall and a strong sulfur odor were reported in Manizales (30 km NW) and in the municipality of Chinchiná (30 km WNW). Satellite images showed continuing sulfur dioxide emissions on 6 August. Web cameras near the volcano recorded a gas-and-steam plume rising 700 m that drifted SW on 8 August. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
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 domesbuilt 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.
19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 1-7 August seismicity at Popocatépetl indicated continuing gas-and-steam emissions that may have contained ash during 4-6 August; cloud cover prevented observations during most of this period. Incandescence from the crater was periodically observed. Gas-and-steam plumes were observed almost daily rising from the crater as high as 2.5 km above the rim. The plumes drifted SW and NW. On 5 August ash plumes rose 1.5 km and drifted SW. On 6 August ash plumes again rose 1.5 km above the crater, and at 1758 an ash plume rose 4 km. Some explosions ejected incandescent tephra that landed on the flanks. Gas-and-steam plumes drifted SW the next day. 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 that during 30 July-3 August three explosions from Sakura-jima's Showa Crater ejected tephra as far as 800 m from the crater. A small explosion from Minami-dake Crater occurred on 31 July. Based on information from JMA, the Tokyo VAAC reported that explosions during 1 and 3-7 July often produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SW, W, and NW.
Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Airacaldera at 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 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.
SHIVELUCH, Central Kamchatka (Russia)
56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 27 July-6 August explosive activity was detected at Shiveluch; a strong explosion detected on 27 July possibly produced an ash plume that rose 10 km (32,800 ft) a.s.l. Satellite imagery showed a daily thermal anomaly on the lava dome. Observers noted gas-and-steam activity during 28-29 and 21 July. TheAviation Color Code remained at Orange.
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 Holocenewithin 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 andesiticvolcano 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 historicaleruptions from Shiveluch occurred in 1854 and 1964.
1.467°S, 78.442°W; summit elev. 5023 m
IG reported that during 1-5 August visual observations of Tungurahua were limited due to cloud cover. A small steam plume rose from the crater on 3 August and drifted W. Explosions on 5 August vibrated windows in nearby areas and produced sounds resembling gunshots. A plume rose 3 km above the crater and drifted W. Explosions during 5-6 August produced gas plumes with small amounts of ash that drifted WSW. Steam plumes rose 100 m above the crater the next day.
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 by pyroclastic 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: Supplied by Michael Moore. Mt Tongariro on Sunday August 5, two days before erupting.
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