New unrest has been noticed around 7 volcanoes, ongoing activity was reported for 10 volcanoes. This report covers active volcanoes in the world recorded from August 29 – September 4, 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.
New Activity/Unrest: | Bezymianny, Central Kamchatka (Russia) | Grozny Group, Iturup Island | Krakatau, Indonesia | Little Sitkin, Aleutian Islands | Soufrière Hills, Montserrat | Tiatia, Kunashir Island |Tungurahua, Ecuador.
Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Cleveland, Chuginadak Island | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Nevado del Ruiz, Colombia | Popocatépetl, México | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia).
BEZYMIANNY, Central Kamchatka (Russia)
55.978°N, 160.587°E; summit elev. 2882 m
KVERT reported that seismic activity at Bezymianny had increased in the middle of August. During 24-31 August levels were moderate; 17 events were recorded on 28 August and 71 events were recorded on 31 August. Observers noted weak-to-moderate fumarolic activity during 25-26 and 29 August; cloud cover prevented observations on the other days. A thermal anomaly was detected in satellite imagery on 25 August.
Based on seismic data analyses, an explosive eruption occurred from 0716 to 0745 on 2 September. Ash plumes rose to altitudes of 10-12 km (32,800-39,400 ft) a.s.l. and drifted more than 1,500 km ENE. A thermal anomaly observed in satellite imagery was very bright before the explosion. The Aviation Color Code was raised to Orange, then Red. Ash plumes rose to an altitude of 4 km (13,100 ft) a.s.l. and drifted NE later that day, then ash emissions ceased. Ash plumes continued to be detected in satellite imagery and drifted 450-600 km ENE and SE. The Aviation Color Code was lowered to Yellow. On 3 September seismic activity was low. A viscous lava flow effused on the lava-dome flank, and was accompanied by fumarolic activity and hot avalanches.
Geologic summary: Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, 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.
GROZNY GROUP, Iturup Island
45.026°N, 147.922°E; summit elev. 1211 m
Based on visual observations and analyses of satellite imagery, SVERT reported that during 23 August-3 September fumarolic activity at Grozny Group increased. The Aviation Color Code remained at Yellow.
Geologic summary: The Grozny volcano group in central Iturup Island contains the complex volcanoes of Ivan Grozny and Tebenkov. The former has a 3-3.5 km diameter caldera that is open to the south, where the large, 1158-m-high andesitic Grozny extrusion dome (also known as Etorofu-Yake-yama) was emplaced. Several otherlava domes of Holocene age were constructed to the NE; extrusion of these domes has constricted a former lake in the northern side of the caldera to an extremely sinuous shoreline. The forested andesitic Tebenkov volcano, also known as Odamoi-san, lies immediately to the NE of the Grozny dome complex. The large Machekh crater, which displays strong fumarolic activity, lies immediately south of Tebenkov. Historical eruptions, the first of which took place in 1968, have been restricted to Ivan Grozny.
6.102°S, 105.423°E; summit elev. 813 m
CVGHM reported that during 1 June-1 September observations of Anak Krakatau were often prevented by fog; occasionally diffuse white plumes were observed rising from the crater in June. Seismicity increased significantly in August. On 2 September seismicity again increased, and at 1830 a Strombolian eruption ejected lava 200-300 m above the crater. The Alert Level remained at 2 (on a scale of 1-4). Residents and visitors were warned not to approach the volcano within 1 km of the crater.
Based on analyses of satellite imagery, the Darwin VAAC reported that on 3 September ash plumes rose to altitudes of 2.4-4.3 km (8,000-14,000 ft) a.s.l. and drifted 35-95 km N.
Geologic summary: Renowned Krakatau volcano lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, resulted in a 7-km-wide caldera. Remnants of this volcano formed Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. The post-collapse cone of Anak Krakatau (Child of Krakatau), constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan, has been the site of frequent eruptions since 1927.
LITTLE SITKIN, Aleutian Islands
51.95°N, 178.543°E; summit elev. 1174 m
AVO reported that at approximately 1915 on 29 August a swarm of high-frequency earthquakes was detected at Little Sitkin. The anomalous seismic activity continued through the night, prompting AVO to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory. The rate of anomalous seismicity varied during 30-31 August; the two most active periods were during the morning of 30 August and at about 0400 on 31 August. The rate of earthquakes started to decline at around 0600 on 31 August, but remained elevated through 3 September. Little Sitkin is monitored by a four-station seismic network as well as satellite imagery.
Geologic summary: Diamond-shaped Little Sitkin Island is bounded by steep cliffs on the east, north, and NE sides. Little Sitkin volcano contains two nested calderas. The older, nearly circular Pleistocene caldera is 4.8 km wide, may have once contained a caldera lake, and was partially filled by a younger cone formed mostly ofandesitic and dacitic lava flows. The elliptical younger caldera is 2.7 x 4 km wide; it lies within the eastern part of the older caldera and shares its eastern and southern rim. The younger caldera partially destroyed the lava cone within the first caldera and is of possible early Holocene age. Young-looking dacitic lava flows, erupted in 1828 (Kay, in Wood and Kienle 1990), issued from the central cone within the younger caldera and from a vent on the west flank outside the older caldera. Fumarolic areas are found near the western coast, along the NW margin of the older caldera, and from the summit crater down the southern flank for a 1 km distance.
SOUFRIERE HILLS, Montserrat
16.72°N, 62.18°W; summit elev. 915 m
MVO reported that during 24-31 August activity at the Soufrière Hills lava dome was at a low level, although seismicity remained slightly elevated. At 1545 on 29 August a small pyroclastic flow traveled 1-1.5 km E down the Tar River Valley. The flow lasted 75 seconds, generated an ash cloud that rose 900-1,200 m and drifted W over Plymouth, and had an extensive fine-grained surge component. The Hazard Level remained at 2 (on a scale of 1-5).
Geologic summary: The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption.
TIATIA, Kunashir Island
44.351°N, 146.256°E; summit elev. 1819 m
SVERT reported that a weak thermal anomaly over Tiatia was detected in satellite images on 1 September. TheAviation Color Code remained at Yellow.
Geologic summary: Tiatia volcano, one of the most impressive of the Kuril Islands, consists of a beautifully symmetrical cone that rises above the broad rim of an erosionally furrowed, 2.1 x 2.4 km wide caldera. The 1819-m-high Tiatia (also known as Chacha-dake) occupies the NE tip of Kunashir Island and morphologically resembles Mount Vesuvius. The pristine-looking conical central cone, mostly formed by basaltic to basaltic-andesite strombolian eruptions, rises 400 m above the floor of the caldera and contains a 400 x 250 m wide crater with two explosion vents separated by a linear septum. Fresh lava flows cover much of the SW caldera floor and have overflowed the rim, extending to the foot of the older somma, which formed during the latePleistocene or early Holocene. A lava flow from a flank cone on the northern caldera rim reached the Sea of Okhotsk. A major explosive eruption in 1973 was the first since Tiatia's initial historical eruption in 1812.
1.467°S, 78.442°W; summit elev. 5023 m
IG reported that during 29 August-4 September visual observations of Tungurahua were often limited due to cloud cover. Moderate seismicity was detected during 29-30 August and a few earthquakes were felt by residents. On 30 August steam plumes with low ash content rose 500 m above the crater and drifted W. Ashfall was reported in Manzano (8 km SW) and Choglontus. Incandescent blocks rolled 300 m down the flanks, roaring was heard, and structures in nearby areas vibrated. During 31 Auguts-1 September steam plumes rose 300-500 m and drifted W. Glow emanated from the crater and incandescent blocks rolled down the flanks, up to 500 m on 31 August. Ashfall was reported in Manzano. An explosion produced a plume that rose 300 m on 3 September, and a steam plume drifted W on 4 September.
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.
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 30 August-4 September ash plumes from Batu Tara rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted 45-55 km W 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 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 satellite images of Cleveland from 17 August showed that the summit crater was tephra-covered, funnel-shaped, and contained no lava dome. Cloud cover prevented observations during 28 August-3 September. 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
INSIVUMEH reported that during 29-30 August lava flows from Fuego traveled 250 m down the Taniluyá drainage (SW), generating block avalanches that produced gray plumes and reached vegetated areas.
Seismicity increased on 3 September. During 3-4 September constant Strombolian explosions generated ash plumes that rose 900 m above the crater and drifted 8 km S and SW. The eruption was heard in areas 10 km away and vibrated structures in Panimaché (8 km SW), Morelia (8 km SW), and Santa Sofia (12 km SE). Lavawas ejected 100 m high and spilled over the crater rim. Lava flows traveled 3 km down the Taniluyá and the Ceniza (SSW) drainages, producing block avalanches that again reached vegetated areas. A third lava flow descended the Las Lajas drainage (SE). Pyroclastic flows traveled SE. Ash plumes drifted 10-12 km S and SW, and produced ashfall in Panimaché, Morelia, Santa Lucía, Cotzumalguapa, Tierra Linda, and Popoya.
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 weak-to-moderate seismic activity from Karymsky during 24-31 August. Volcanologists working on the flank observed explosive activity; ash plumes rose to an altitude of 4.5 km (14,800 ft) a.s.l. on 25 August. Satellite imagery showed a thermal anomaly on the volcano during 23-24, 26, and 28 August. The Aviation Color Code remained at Orange.
Geologic summary: Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano 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 28 August-4 September HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas. On 28 August two major collapses of the inner wall significantly disrupted the lake's circulation.
Lava flows were periodically active on the pali and the coastal plain. At Pu'u 'O'o, a collapse of the crater floor just before 0400 on 30 August enlarged the newer pit crater at the S edge, making it appear slightly larger in the webcam views than the older, active, pit crater on the E edge. A new pit crater formed at the N edge of the floor after 1000, and by 1300 it was filled with lava. The N rim of the E pit crater fell into the lava lake there just before 1700. During 30-31 August incandescence emanated from the lava lake in the E pit crater but was absent from the S pit crater. A few scattered areas of flow activity on the coastal plain more than 2 km from the coast were visible on web cameras. On 1 September glow emanated from the E and S pit craters. Crusted lava filled the N pit crater and sagged, and a couple of small lava flows traveled from the edge onto the sagging crust. The N pit appeared to be a passive lava lake, without a direct source of magma underneath. A collapse in the roof of thelava tube at the base of the SE flank of Pu'u 'O'o continued to glow but was less bright the next day.
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 30-31 August variations in volcanic tremor amplitude were detected at Nevado del Ruiz, possibly associated with continuing gas and ash emissions. Seismic activity was low during 2-4 September. Cloud cover mostly prevented observations of the volcano; a white gas plume rose 200 m on 4 September and drifted W and SW. During 3-4 September field measurements and analysis of satellite imagery showed a significant amount of sulfur dioxide in the atmosphere. 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 29 August-4 September seismicity at Popocatépetl indicated continuing gas-and-steam emissions that may have contained ash; cloud cover often prevented visual observations of the volcano. Incandescence from the crater was observed at night. Gas plumes, that were sometimes bluish, rose up to 1 km above the crater and drifted NE, W, SW, and WSW. On 1 September the Alert Level was lowered to Yellow, Phase Two.
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 27-31 August five explosive eruptions from Sakura-jima's Showa Crater were detected and ejected tephra as far as 1.3 km from the crater. Gas measurements taken on 20 and 22 August showed elevated sulfur dioxide emissions compared to the previous week. Based on information from JMA, the TokyoVAAC reported that explosions during 29-30 August and 1-4 September often produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. The plumes sometimes drifted N and NE. Pilots observed ashplumes during 1-2 September that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l.
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.
SANTA MARIA, Guatemala
14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that on 29 August fumarolic plumes from Santa María's Caliente dome rose 250-300 m and drifted SE. Small avalanches were active on the S part of the dome. Explosions on 3 September producedash plumes that rose 200-800 m above Caliente dome and drifted W and SW. Four active lava flows generatedblock avalanches that traveled S down the Rio Nima I and Rio Nima II drainages. On 4 September hot lahars traveled S down the Rio Nima I and San Isidro drainages. The lahar in the San Isidro channel was 30 m wide and 2 m deep, emitted a sulfur odor, and carried blocks up to 1 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 periodic lava 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 24-31 August a viscous lava flow was active on the NE flank of Shiveluch's lava dome and was accompanied by hot avalanches. Satellite imagery showed a thermal anomaly over the lava dome during 24-26 August; cloud cover prevented observations on the other days. The Aviation Color Coderemained 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 historical eruptions from Shiveluch occurred in 1854 and 1964.
Source: Global Volcanism Program
Featured image: Little Sitkin volcano. Image credit: Aleutian Fox's photostream
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