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Smithsonian/USGS Weekly Volcanic Activity Report 6-12 July 2011
From: "Kuhn, Sally" <KUHNS@xxxxxx>
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Smithsonian/USGS Weekly Volcanic Activity Report
6-12 July 2011
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Aoba, Vanuatu (SW Pacific) | Etna, Sicily (Italy) | Ijen, Eastern Java (Indonesia) | Katla, Southern Iceland | Lokon-Empung, Sulawesi | Puyehue-Cordón Caulle, Central Chile | Stromboli, Aeolian Islands (Italy)
Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Dukono, Halmahera | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Pagan, Mariana Islands | Sakura-jima, Kyushu | Shiveluch, Central Kamchatka (Russia) | Slamet, Central Java (Indonesia)
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
AOBA Vanuatu (SW Pacific) 15.40°S, 167.83°E; summit elev. 1496 m
On 11 July the Vanuatu Geohazards Observatory noted that there had been recent increases in activity from Aoba and that local earthquakes were volcanic. Satellite images collected by the Ozone Monitoring Instrument showed sulfur dioxide emissions. Observations on 4 June revealed that small explosions had been occurring from the crater lake and were accompanied by local ashfall around the crater. Some villagers in the N and W parts of the island had observed the explosions. The Vanuatu Volcano Alert Level (VVAL) remained at 1 (on a scale of 0-4).
Geologic Summary. Aoba, also known as Ambae, is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.
Source: Vanuatu Geohazards Observatory http://www.geohazards.gov.vu/
ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
Sezione di Catania - Osservatorio Etneo reported that explosions from the pit crater located on the E flank of Etna's SE Crater cone were heard on the morning of 4 July. Incandescence was observed later that evening. Small Strombolian eruptions were recorded by a camera during 5-6 July.
On 7 July Strombolian activity gradually increased along with volcanic tremor amplitude. Small pyroclastic cones began to grow on the crater floor. During the next morning, volcanic tremor amplitude clearly increased. Shortly thereafter it abruptly decreased and the Strombolian activity completely ceased. During the morning of 9 July, Strombolian activity resumed and volcanic tremor amplitude rose rapidly. Around noon lava overflowed the E rim of the crater and followed the path of lava flows from the previous eruption, into the upper W part of the Valle del Bove. Later that day Strombolian explosions turned into a continuous lava fountain. A dense eruptive plume rose several kilometers high and drifted S and SE, causing ash and lapilli fall in populated areas including Trecastagni, Viagrande, and Acireale towards the SE, and between Nicolosi and Catania towards the S, forcing the closure of the Fontanarossa international airport in Catania. A few hours later volcanic tremor amplitude dropped to very low levels and all eruptive activity ceased.
Geologic Summary. Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna's summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania.
Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/
IJEN Eastern Java (Indonesia) 8.058°S, 114.242°E; summit elev. 2799 m
The Darwin VAAC reported that on 10 July a pilot observed an ash plume drifting W from Ijen at an altitude of 3.7 km (12,000 ft) a.s.l.
Geologic Summary. The Ijen volcano complex consists of a group of small stratovolcanoes constructed within the large 20-km-wide Ijen (Kendeng) caldera. The N caldera wall forms a prominent arcuate ridge, but elsewhere the caldera rim is buried by post-caldera volcanoes, including Gunung Merapi stratovolcano, which forms the 2,799 m high point of the Ijen complex. Immediately W of Gunung Merapi is the renowned historically active Kawah Ijen volcano, which contains a nearly 1-km-wide, turquoise-colored, acid crater lake. The picturesque lake is the site of a labor-intensive sulfur mining operation, in which sulfur-laden baskets are hand-carried from the crater floor. A half dozen small-to-moderate phreatic eruptions have taken place from Kawah Ijen during the 20th century.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
KATLA Southern Iceland 63.63°N, 19.05°W; summit elev. 1512 m
The Iceland Met Office and news sources reported that on 9 July a jökulhlaup from Mýrdalsjökull, the ice sheet that covers Katla, originated from three ice cauldrons in the SE part of the caldera. During previous weeks microseismicity had been registered near several of the ice cauldrons. Around the time of peak harmonic tremor, in the early evening on 8 July, the Mýrdalsjökull flood monitoring system indicated increased conduction. The water level reached the bridge around midnight and damaged the sensors. According to news articles, one new cauldron that had formed, along with cracks in the glacier around the cauldrons, may have been caused by a small eruption at Katla although no evidence of an eruption was observed. The jökulhlaup had destroyed a 128-m-long bridge and caused damage, resulting in the closing of part of the Ring Road. About 200 people were evacuated from the area but allowed to return home later that day. On 10 July the water had subsided and returned to normal levels.
Geologic Summary. Katla volcano, located near the southern end of Iceland's eastern volcanic zone, is hidden beneath the Myrdalsjökull icecap. The subglacial basaltic-to-rhyolitic volcano is one of Iceland's most active and is a frequent producer of damaging jökulhlaups, or glacier-outburst floods. A large 10 x 14 km subglacial caldera with a long axis in a NW-SE direction is up to 750 m deep. Its high point reaches 1380 m, and three major outlet glaciers have breached its rim. Although most historical eruptions have taken place from fissures inside the caldera, the Eldgjá fissure system, which extends about 60 km to the NE from the current ice margin towards Grímsvötn volcano, has been the source of major Holocene eruptions. An eruption from the Eldgjá fissure system about 934 AD produced a voluminous lava flow of about 18 cu km, one of the world's largest known Holocene lava flows. Katla has been the source of frequent subglacial basaltic explosive eruptions that have been among the largest tephra-producers in Iceland during historical time and has also produced numerous dacitic explosive eruptions during the Holocene.
Sources: Icelandic Met Office http://en.vedur.is/,
MBL http://www.mbl.is/frettir/innlent/2011/07/09/sja_sprungur_i_joklinum/,
Iceland Review http://www.icelandreview.com/icelandreview/daily_news/Cracks_in_Glacier,_No_Sign_of_Katla_Eruption_0_380019.news.aspx,
Iceland Review http://www.icelandreview.com/icelandreview/daily_news/Flood_Video,_Only_Danger_on_Glacier,_People_Return_Home_0_380021.news.aspx,
Iceland Review http://www.icelandreview.com/icelandreview/daily_news/Still_Uncertain_Whether_Katla_Volcano_Erupted_0_380068.news.aspx
LOKON-EMPUNG Sulawesi 1.358°N, 124.792°E; summit elev. 1580 m
CVGHM reported that during 28 June-9 July white plumes rose 50-400 m above Tompaluan crater, in the saddle between the Lokon-Empung peaks, and gray ash plumes rose 100-500 m above the crater. An ash eruption on 10 July produced white-to-gray plumes that rose 200-400 m above the crater. Fluctuations in the sulfur dioxide gas emission rate were noted during 30 June-10 July. Based on gas flux, seismicity, visual observations, and hazard assessment CVGHM raised the Alert Level to 4 (on a scale of 1-4). On 11 July, the Darwin VAAC reported that ash plumes detected in satellite imagery rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW. According to news articles, close to 1,000 residents were evacuated from the area during 11-12 July.
Geologic Summary. The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km apart) has a flat, craterless top. The morphologically younger Empung volcano has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred.
Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/,
Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html,
Associated Press http://www.cbsnews.com/stories/2011/07/12/501364/main20078878.shtml
PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
OVDAS-SERNAGEOMIN reported that during 6-8 July cameras installed around the Puyehue-Cordón Caulle volcanic complex recorded eruption plumes that rose no higher than 2 km above the Cordón Caulle rift zone and drifted N and NE. On 6 July satellite imagery indicated that the plume drifted 75 km NE. During 7-8 July explosions recorded by the seismic network corresponded to increases in the plume height and, on 7 July, caused windows in Riñinahue to vibrate. According to news articles, numerous flights in and around Argentina and Uruguay were cancelled on 8 July and some airports had remained closed.
On 9 July seismicity indicated that lava flows had ceased. During 9-11 July weather conditions prevented views of the eruption plume by cameras installed around the volcano. Based on analysis of satellite imagery, the Buenos Aires VAAC stated on 9 July that, although ash plumes rose to an altitude of 3 km (10,000 ft), activity was weakening. Ash was again detected by satellite during periods of clear weather the next day. The Alert Level remained at Red.
Geologic Summary. The Puyehue-Cordón Caulle volcanic complex (PCCVC) is a large NW-SE-trending late-Pleistocene to Holocene basaltic-to-rhyolitic transverse volcanic chain SE of Lago Ranco. The 1799-m-high Pleistocene Cordillera Nevada caldera lies at the NW end, separated from Puyehue stratovolcano at the SE end by the Cordón Caulle fissure complex. The Pleistocene Mencheca volcano with Holocene flank cones lies NE of Puyehue. The basaltic-to-rhyolitic Puyehue volcano is the most geochemically diverse of the PCCVC. The flat-topped, 2236-m-high Puyehue volcano was constructed above a 5-km-wide caldera and is capped by a 2.4-km-wide summit caldera of Holocene age. Lava flows and domes of mostly rhyolitic composition are found on the eastern flank of Puyehue. Historical eruptions originally attributed to Puyehue, including major eruptions in 1921-22 and 1960, are now known to be from the Cordón Caulle rift zone. The Cordón Caulle geothermal area, occupying a 6 x 13 km wide volcano-tectonic depression, is the largest active geothermal area of the southern Andes volcanic zone.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/,
Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html,
Agence France-Presse http://ph.news.yahoo.com/volcanic-ash-cloud-grounds-more-flights-argentina-161459262.html
STROMBOLI Aeolian Islands (Italy) 38.789°N, 15.213°E; summit elev. 924 m
Sezione di Catania - Osservatorio Etneo reported that on 5 July a high pyroclastic jet formed in the S part of Stromboli's crater terrace producing tephra that fell back onto the Pizzo sopra la Fossa. Seismic data indicated that other craters on the terrace were also active. A similar but less powerful explosion occurred from the same vent on 10 July.
Geologic Summary. Spectacular incandescent nighttime explosions at Stromboli volcano have long attracted visitors to the "Lighthouse of the Mediterranean."Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout historical time. The small, 926-m-high island of Stromboli is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The active summit vents are located at the head of the Sciara del Fuoco, a horseshoe-shaped scarp formed as a result of slope failure that extends to below sea level and funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded at Stromboli since Roman times.
Source: Sezione di Catania - Osservatorio Etneo http://www.ct.ingv.it/
Ongoing Activity
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 9-11 July ash plumes from Batu Tara rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted 75 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.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 6-7 July ash plumes from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 55 km NW.
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.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 1-8 July moderate seismic activity continued at Karymsky and possible ash plumes rose to an altitude of 4 km (13,100 ft) a.s.l. Satellite imagery showed a thermal anomaly on the volcano during 2 and 4-5 June, and ash plumes that drifted 14 km NW and 38 km N on 2 and 5 July, respectively. The Aviation Color Code remained at Orange.
Based on information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 12 July an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted SW.
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.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
HVO reported that two lava lakes at Kilauea were active during 6-12 July. The level of the summit lava lake fluctuated deep in the vent inset within the E wall of Halema'uma'u Crater and circulated with various patterns. Spattering occurred at locations along the W edge of the lake. Periodic measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash nearby. At Pu'u 'O'o, lava from vents near the NE edge and, to a lesser degree, along the W edge of the perched lava lake in the center of the crater floor continued to fill the lake. The lake level fluctuated and flowed through rim breaches, sending lava onto the Pu'u 'O'o crater floor. The near-vertical rim of the perched pond, which was elevated about 5 m higher than the surrounding sub-horizontal crater floor on the E side, continued to be uplifted; the crater floor and perched lake rims formed a nearly-continuous ramp sloping away from the lake.
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.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
KIZIMEN Eastern Kamchatka (Russia) 55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 25-27 June observers on Tolbachik's flanks noted strong fumarolic activity from Kizimen. Deformation was also noted on those days. During 1-8 July seismicity was above background levels and volcanic tremor continued to be detected. A bright thermal anomaly was detected in satellite imagery during 2-5 July; cloud cover prevented observations of the volcano on the other days. The Aviation Color Code remained at Orange.
Based on information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 12 July an ash plume rose to an altitude of 6.4 km (21,000 ft) a.s.l. and drifted E.
Geologic Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php,
Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
PAGAN Mariana Islands 18.13°N, 145.80°E; summit elev. 570 m
A Northern Mariana Islands status report noted that on 7 July a low-level gas-and-steam plume with possible fine ash was detected in satellite imagery as well as noted by observers on the island. Low-level gas-and-steam plumes had been detected in satellite imagery during the previous few weeks. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Geologic Summary. Pagan Island, the largest and one of the most active of the Mariana Islands volcanoes, consists of two stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount Pagan at the NE end of the island rises above the flat floor of the caldera, which probably formed during the early Holocene. South Pagan is a 548-m-high stratovolcano with an elongated summit containing four distinct craters. Almost all of the historical eruptions of Pagan, which date back to the 17th century, have originated from North Pagan volcano. The largest eruption of Pagan during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands, Office of the Governor, United States Geological Survey Volcano Hazards Program http://volcanoes.usgs.gov/nmi/activity/index.php
SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m
According to pilot observations, the Tokyo VAAC reported that on 7 and 10 July ash plumes rose from Sakura-jima to altitudes of 1.2-2.4 km (4,000-8,000 ft) a.s.l. Reports from JMA stated that plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. on 8, 10, and 12 July.
Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera 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.
Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported moderate seismic activity at Shiveluch during 1-8 July. Seismic data indicated that possible ash plumes rose to an altitude of 4.5 km (14,800 ft) a.s.l. on 4 and 6 July. Satellite imagery showed a thermal anomaly on the lava dome during 2-5 July and gas-and-ash plumes that drifted 78 km NE during 4-5 July. The Aviation 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 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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
SLAMET Central Java (Indonesia) 7.242°S, 109.208°E; summit elev. 3428 m
CVGHM reported that between 6 September 2009 and July 2011 eruptions from Slamet had been absent and plumes (likely steam) rose as high as 500 m above the crater. Seismicity and the temperature of hot water from springs both decreased. On 11 July, the Alert Level was lowered to 1 (on a scale of 1-4).
Geologic Summary. Slamet, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. Slamet is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper eastern flank on the younger edifice fed a lava flow that extends 6 km to the east. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time. Historical eruptions, recorded since the 18th century, have originated from a 150-m-deep, 450-m-wide, steep-walled crater at the western part of the summit and have consisted of explosive eruptions generally lasting a few days to a few weeks.
Source: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/
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