*****************************************************************************************************
Smithsonian / USGS Weekly Volcanic Activity Report 8-14 July 2015
From: "Kuhn, Sally" <KUHNS@si.edu>
*****************************************************************************************************
Smithsonian / USGS Weekly Volcanic Activity Report
8-14 July 2015
Sally Kuhn Sennert - Weekly Report Editor (kuhns@si.edu)
URL: http://www.volcano.si.edu/reports_weekly.cfm
New Activity/Unrest: Colima, Mexico | Hakoneyama, Honshu (Japan) | Raung, Eastern Java (Indonesia) | Sangeang Api, Indonesia | Sirung, Pantar Island (Indonesia)
Ongoing Activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia | Tungurahua, Ecuador | Ubinas, Peru | Zhupanovsky, Eastern Kamchatka (Russia)
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
Colima | Mexico | 19.514°N, 103.62°W | Summit elev. 3850 m
In a 7 July bulletin, the Unidad Estatal de Protección Civil de Colima reported that during the previous week explosions from a fast-growing lava dome at Colima generated ash plumes that rose 3 km above the crater. Incandescent rock avalanches, from explosions and the lava dome overtopping the crater rim, descended the flanks. Ashfall was reported in various communities downwind. The report warned the public not to enter an area within a 5-km radius of the crater, and to avoid drainages within 14 km due to lahar hazards. La Coordinación Nacional de Protección Civil reported that during 7-10 July a gradual increase in the number of emissions and landslides was detected. Pyroclastic flows traveled at most 2.5 km down the N, W, and S flanks. During 9-10 July incandescent material was ejected from the crater.
Based on satellite images and webcam views, the Washington VAAC reported an intense thermal anomaly and constant ash emissions on 10 July. A large event at 1200 produced an ash plume that rose to an altitude of 7.6 km (25,000 ft) a.s.l. and drifted 150 km W. La Coordinación Nacional de Protección Civil noted that activity further increased at 2017 on 10 July, characterized by incandescent material descending the WSW flanks, pyroclastic flows, and ash plumes that rose 4 km above the crater. Ash fell in the communities of La Yerbabuena (5-cm-thick ash deposits), La Becerrera (88 SW), San Antonio, Carrizalillo, El Naranjal, Nuevo Naranjal, and Suchitlán (18 km SSW) in Colima State. The Unidad Estatal de Protección Civil de Colima ordered 19 residents in La Yerbabuena to evacuate, and some residents in nearby towns self-evacuated. A pyroclastic flow traveled 9 km S. By 1030 on 11 July there were 70 confirmed evacuees in shelters. Citing large eruptions in the past, La Coordinación Nacional de Protección Civil enforced a preventative evacuation within 12 km of the crater. Ashfall was reported in Comala, Villa de Alvarez, and Colima. An additional 70 people had evacuated, and the national airport, El Aeropuerto Nacional de Colima, suspended operations due to ashfall. Ejected incandescent material, ash emissions, incandescent landslides, and pyroclastic flows continued at a moderate level during 11-12 July. Evacuations continued on 12 July, and ashfall persisted in Comala, Villa de Alvarez, and Colima. The report noted that La Unidad Estatal de Protección Civil and Bomberos de Jalisco continued to monitor the towns of Lomas de las Flores and San José del Carmen, and the municipality of Zapotitlán de Vadillo because they were the areas most affected by ashfall.
Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.
Sources: Unidad Estatal de Protección Civil de Colima www.proteccioncivil.col.gob.mx;
La Coordinación Nacional de Protección Civil http://www.proteccioncivil.gob.mx/;
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
Hakoneyama | Honshu (Japan) | 35.233°N, 139.021°E | Summit elev. 1438 m
On 12 July JMA reported that the webcam continued to record vigorous fumarolic plumes rising from Hakoneyama's Owakudani hot spring area. The Alert Level remained at 3 (on a 5-level scale).
Geologic Summary. Hakoneyama volcano is truncated by two overlapping calderas, the largest of which is 10 x 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000-60,000 years ago. Scenic Lake Ashi lies between the SW caldera wall and a half dozen post-caldera lava domes that were constructed along a SW-NE trend cutting through the center of the calderas. Dome growth occurred progressively to the south, and the largest and youngest of these, Kamiyama, forms the high point of Hakoneyama. The calderas are breached to the east by the Hayakawa canyon. A phreatic explosion about 3000 years ago was followed by collapse of the NW side of Kamiyama, damming the Hayakawa valley and creating Lake Ashi. The latest magmatic eruptive activity about 2900 years ago produced a pyroclastic flow and a lava dome in the explosion crater, although phreatic eruptions took place as recently as the 12-13th centuries CE. Seismic swarms have occurred during the 20th century. Lake Ashi, along with major thermal areas in the caldera, forms a popular resort area SW of Tokyo.
Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/
Raung | Eastern Java (Indonesia) | 8.125°S, 114.042°E | Summit elev. 3332 m
PVMBG reported that during 1-8 July gray plumes rose 100-500 m above Raung's crater rim, crater incandescence was observed, and rumbling and thumping sounds were noted. Seismicity was dominated by high-amplitude tremor; deformation data suggested magma migrating to the surface. The Alert Level remained at 3 (on a scale of 1-4), and the public was reminded not to approach the crater within a 3-km radius. BNPB reported that gray ash plumes continued to rise as high as 500 m above the crater through 11 July. Ash plumes drifted in various directions depending on the altitude: SE and S at lower altitudes and SE, S, W, and N at higher altitudes.
Based on PVMBG notices, wind data, and satellite images, the Darwin VAAC reported that during 8-12 July ash plumes rose to an altitude of 4.3-5.2 km (14,000-17,000 ft) a.s.l. and drifted as far as 1,040 km E, SE, and S. According to news articles, increased activity during 9-10 July caused flight cancelations and several airports to close, including those on Bali and Lombok, and in Banyuwangi and Jember in East Java. The article also noted that dozens of flight had been canceled during the previous week. Another article noted that the Bali airport, in addition to another airport in Java, again closed on 12 July, a day after it had reopened.
Geologic Summary. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The 3332-m-high, unvegetated summit of Gunung Raung is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively.
Sources: Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/;
Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/;
Agence France-Presse (AFP) http://www.thenational.ae/world/mount-raung-eruption-causes-closure-of-bali-airport-again;
The Weather Channel http://www.weather.com/news/news/indonesia-mount-raung-volcano
Sangeang Api | Indonesia | 8.2°S, 119.07°E | Summit elev. 1949 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 8 July an ash plume from Sangeang Api rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted over 35 km SE.
Geologic Summary. Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, 1949-m-high Doro Api and 1795-m-high Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/
Sirung | Pantar Island (Indonesia) | 8.508°S, 124.13°E | Summit elev. 862 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 8 July an ash plume from Sirung drifted 55 km W at an altitude of 1.5 km (5,000 ft) a.s.l.
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 caldera whose 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. Forested Gunung Topaki, the 1390-m high point of the volcanic chain, lies at the SW end and contains a symmetrical summit crater.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/
Ongoing Activity
Aira | Kyushu (Japan) | 31.593°N, 130.657°E | Summit elev. 1117 m
JMA reported that during 6-13 July small-scale explosions occurred at Showa Crater at Aira Caldera's Sakurajima volcano. One larger explosion ejected ballistics 200-300 m above the crater. Incandescence from the crater was occasionally visible at night. Rumbling was occasionally heard several tens of kilometers away. The Alert Level remained at 3 (on a 5-level scale).
Geologic Summary. The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. 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: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/
Dukono | Halmahera (Indonesia) | 1.68°N, 127.88°E | Summit elev. 1335 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 9-14 July ash plumes from Dukono rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted 35-185 km NW, N, and NE.
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 north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the 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) ftp://ftp.bom.gov.au/anon/gen/vaac/
Karymsky | Eastern Kamchatka (Russia) | 54.049°N, 159.443°E | Summit elev. 1513 m
KVERT reported that explosive activity at Karymsky likely continued during 3-10 July; a thermal anomaly over the volcano was visible in satellite images on 6 July. Weather clouds obscured views of the volcano on the other days. 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 during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-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.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
HVO reported that seismicity beneath Kilauea's summit, upper East Rift Zone, and Southwest Rift Zone was at background levels during 8-14 July. The lava lake continued to circulate and spatter in the Overlook vent. Webcams recorded multiple incandescent outgassing vents within Pu'u 'O'o. The June 27th NE-trending lava flow continued to be active with surface flows within 8 km NE of Pu'u 'O'o Crater. Satellite images showed expansion of the flow field since 6 July, with gradual northward advancement of the most western and north-pointing branch of the flow field.
Geologic Summary. Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions of Kilauea are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 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/
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that during 3-10 July lava-dome extrusion onto Sheveluch's N flank was accompanied by fumarolic activity. Satellite images showed a thermal anomaly over the dome during 2-4 July. Ash plumes that rose as high as 3.3 km (10,800 ft) a.s.l. were observed during 5-6 July. The Aviation Color Code remained at Orange.
Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
Shishaldin | Fox Islands (USA) | 54.756°N, 163.97°W | Summit elev. 2857 m
AVO reported that seismicity at Shishaldin continued to be elevated over background levels 8-14 July indicating that low-level eruptive activity confined to the summit crater likely continued. Cloud cover prevented satellite and webcam observations. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Geologic Summary. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century.
Source: US Geological Survey Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
Sinabung | Indonesia | 3.17°N, 98.392°E | Summit elev. 2460 m
On 11 July, BNPB reported that activity at Sinabung remained high and was characterized by avalanches, continuous tremor, and high lava-dome growth. The Alert Level remained at 4 (on a scale of 1-4), indicating that people within 7 km of the volcano on the SE sector, and within 6 km in the E sector, should evacuate or remain in alternative housing.
Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.
Source: Badan Nacional Penanggulangan Bencana (BNPB) http://www.bnpb.go.id/
Tungurahua | Ecuador | 1.467°S, 78.442°W | Summit elev. 5023 m
IG reported moderate seismic activity at Tungurahua during 8-14 July, characterized by long-period events, minor instances of tremor, and a few explosions. Cloud cover often prevented visual observations. Steam-and-ash plumes during 9-10 July rose 500 m above the crater and drifted W; minor ashfall was reported in Choglontus (13 km WSW) and El Manzano (8 km SW). An explosion on 12 July produced an ash plume that rose 2 km and caused windows to vibrate in Juive (NW). An explosion on 13 July generated an ash plume that rose 1 km. The next day ashfall was reported in Palitahua (6 km SSW).
Geologic Summary. Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
Ubinas | Peru | 16.355°S, 70.903°W | Summit elev. 5672 m
Instituto Geofísico del Perú (IGP) Observatorio Volcanológico del Sur (OVS) reported that during 7-13 July seismic activity declined. Volcano-tectonic earthquakes continued to decrease and the rate of long-period events slightly increased as compared to the previous week. The number of hybrid events decreased, and tremor associated with emissions was greatly reduced. Explosions were observed on 9 and 11 July, producing ash plumes that drifted NE, E, and S. Ash emissions were observed on other days as well.
Geologic Summary. A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.
Source: Instituto Geofísico del Perú (IGP) http://www.igp.gob.pe/
Zhupanovsky | Eastern Kamchatka (Russia) | 53.589°N, 159.15°E | Summit elev. 2899 m
KVERT reported that explosive activity at Zhupanovsky probably continued during 3-10 July; ash plumes drifted SW on 6 July. Weather clouds obscured views of the volcano on the other days. The Aviation Color Code remained at Orange.
Geologic Summary. The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated volcanic complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene, the fourth is Holocene in age and was the source of all of Zhupanovsky's historical eruptions. An early Holocene stage of frequent moderate and weak eruptions from 7000 to 5000 years before present (BP) was succeeded by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 years BP. Historical eruptions have consisted of relatively minor explosions from the third cone.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
__._,_.___
No comments:
Post a Comment