Smithsonian / USGS Weekly Volcanic Activity Report 29 June-5 July 2016
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Smithsonian / USGS Weekly Volcanic Activity Report
29 June-5 July 2016
Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)
URL: http://www.volcano.si.edu/reports_weekly.cfm
New Activity/Unrest: Kilauea, Hawaiian Islands (USA) | Pacaya, Guatemala | Pavlof, United States | Planchon-Peteroa, Central Chile-Argentina border | Zavodovski, South Sandwich Islands (UK)
Ongoing Activity: Aira, Kyushu (Japan) | Alaid, Kuril Islands (Russia) | Bagana, Bougainville (Papua New Guinea) | Chirpoi, Kuril Islands (Russia) | Colima, Mexico | Dukono, Halmahera (Indonesia) | Fuego, Guatemala | Klyuchevskoy, Central Kamchatka (Russia) | Nevado del Ruiz, Colombia | Popocatepetl, Mexico | Ruapehu, North Island (New Zealand) | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Turrialba, Costa Rica
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
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
HVO reported that during 29 June-5 July the lava lake continued to rise and fall, circulate, and spatter in Kilauea's Overlook vent. Several incandescent vents on Pu'u 'O'o Crater's floor were evident in webcam images. A lava flow originating from a vent on Pu'u 'O'o Crater's E flank continued to advance and spread SE. Webcams recorded bright incandescence from several skylights along the upper part of the tube system supplying lava to the front part of the flow, and also from the flow field. By 29 June the toe of the lava flow had reached the base of the pali (burning vegetation in the adjacent kipuka), and by 3 July it had advanced 690 m onto the coastal plain, 2.6 km from the ocean.
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 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/
Pacaya | Guatemala | 14.381°N, 90.601°W | Summit elev. 2552 m
Based on visual observations and seismic data, INSIVUMEH reported that gas plumes rose from Pacaya during 30 June-5 July. Incandescence from the crater was visible at night.
Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
Pavlof | United States | 55.417°N, 161.894°W | Summit elev. 2493 m
On 1 July AVO reported that seismicity at Pavlof had increased during the previous 24 hours and minor steam emissions had been recorded by the webcam in the morning. The Aviation Color Code was raised to Yellow and Volcano Alert Level was raised to Advisory. Seismicity on 2 July was lower but remained elevated. Tremor ceased on 3 July but was again detected during 4-5 July.
Geologic Summary. The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.
Source: US Geological Survey Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
Planchon-Peteroa | Central Chile-Argentina border | 35.223°S, 70.568°W | Summit elev. 3977 m
Based on Observatorio Volcanológico de los Andes del Sur (OVDAS) observations, on 1 July SERNAGEOMIN reported that seismicity at Planchón-Peteroa had begun increasing above baseline levels on 16 June; during 16-30 June the seismic network detected 944 volcano-tectonic events and 1,635 long-period events. The Alert Level was raised to Yellow.
Geologic Summary. Planchón-Peteroa is an elongated complex volcano along the Chile-Argentina border with several overlapping calderas. Activity began in the Pleistocene with construction of the basaltic-andesite to dacitic Volcán Azufre, followed by formation of basaltic and basaltic-andesite Volcán Planchón, 6 km to the north. About 11,500 years ago, much of Azufre and part of Planchón collapsed, forming the massive Río Teno debris avalanche, which traveled 95 km to reach Chile's Central Valley. Subsequently, Volcán Planchón II was formed. The youngest volcano, andesitic and basaltic-andesite Volcán Peteroa, consists of scattered vents between Azufre and Planchón. Peteroa has been active into historical time and contains a small steaming crater lake. Historical eruptions from the complex have been dominantly explosive, although lava flows were erupted in 1837 and 1937.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/;
Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI) http://www.onemi.cl/
Zavodovski | South Sandwich Islands (UK) | 56.3°S, 27.57°W | Summit elev. 551 m
On 30 March an eruption at Zavodovski was reported and photographed by observers on a fishing vessel, as well as captured by a satellite image. A small ash plume drifted E, producing ashfall on 1/3 to 1/2 of the island. A photo showed bombs being ejected from the crater. One of the world’s largest (if not the largest) penguin colonies resides on the E side of the island and is home to 690,000 breeding pairs. The eruption occurred during molting season in March, when penguins stay ashore. A satellite image captured in May showed an eruption plume coming through the clouds.
Geologic Summary. The 5-km-wide Zavodovski Island, the northernmost of the South Sandwich Islands, consists of a single basaltic stratovolcano with two parasitic cones on the east side. Mount Curry, the island's summit, lies west of the center of the island, which is more eroded on that side. Two fissures extend NE from the summit towards the east-flank craters, and a lava platform is located along the eastern coast. Zavodovski is the most frequently visited of the South Sandwich Islands. It was erupting when first seen in 1819 by the explorer Bellingshausen, and the volcano has been reported to be smoking during subsequent visits.
Source: Peter Fretwell, British Antarctic Survey, personal communication https://www.bas.ac.uk/
Ongoing Activity
Aira | Kyushu (Japan) | 31.593°N, 130.657°E | Summit elev. 1117 m
JMA reported that a small-scale explosion at Showa Crater (at Aira Caldera’s Sakurajima volcano) occurred at 1336 on 29 June. An explosion at 0413 on 2 July generated an ash plume that rose 1.2 km above the crater rim, and ejected tephra as far as 800 m from the crater. 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/
Alaid | Kuril Islands (Russia) | 50.861°N, 155.565°E | Summit elev. 2285 m
KVERT reported that moderate activity at Alaid continued during 24 June-1 July. Satellite images showed a thermal anomaly at the volcano during 28-30 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Geologic Summary. The highest and northernmost volcano of the Kuril Islands, 2285-m-high Alaid is a symmetrical stratovolcano when viewed from the north, but has a 1.5-km-wide summit crater that is breached widely to the south. Alaid is the northernmost of a chain of volcanoes constructed west of the main Kuril archipelago and rises 3000 m from the floor of the Sea of Okhotsk. Numerous pyroclastic cones dot the lower flanks of basaltic to basaltic-andesite Alaid volcano, particularly on the NW and SE sides, including an offshore cone formed during the 1933-34 eruption. Strong explosive eruptions have occurred from the summit crater beginning in the 18th century. Reports of eruptions in 1770, 1789, 1821, 1829, 1843, 1848, and 1858 were considered incorrect by Gorshkov (1970). Explosive eruptions in 1790 and 1981 were among the largest in the Kuril Islands during historical time.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
Bagana | Bougainville (Papua New Guinea) | 6.137°S, 155.196°E | Summit elev. 1855 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 1-5 July ash plumes from Bagana rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted 75 km W and SW.
Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical, roughly 1850-m-high cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and 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. Satellite thermal measurements indicate a continuous eruption from before February 2000 through at least late August 2014.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/
Chirpoi | Kuril Islands (Russia) | 46.525°N, 150.875°E | Summit elev. 742 m
SVERT reported that a thermal anomaly at Snow, a volcano of Chirpoi, was detected in satellite images during 29-30 June and on 1 July. The Aviation Color Code remained at Yellow.
Geologic Summary. Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.
Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/?id_d=659
Colima | Mexico | 19.514°N, 103.62°W | Summit elev. 3850 m
Based on information from the Mexico City MWO and webcam views, the Washington VAAC reported that on 29 June an ash plume from Colima rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted W.
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.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html
Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 29 June-1 July and on 5 July ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted NE, E, and SE.
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/
Fuego | Guatemala | 14.473°N, 90.88°W | Summit elev. 3763 m
INSIVUMEH reported that during 30 June-5 July explosions at Fuego generated ash plumes that rose as high as 950 m and drifted W and SW. Some explosions also ejected incandescent material as high as 150 m that then fell onto the flanks and caused minor avalanches. In a special bulletin posted on 5 July, INSIVUMEH noted that 18 explosions were registered within a 24-hour period. Ash plumes rose as high as 1 km and drifted W and SW.
Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m
KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 24 June-1 July. Satellite and video data showed a lava flow continuing to effuse on the SE flank, down the Apakhonchich drainage. Two rock avalanches down the Apakhonchich drainage were recorded by a webcam at 2115 and 2350 on 24 June; ash plumes drifted W and NW. Satellite images showed an intense daily thermal anomaly over the volcano, and gas-and-steam plumes that drifted about 60 km E and W during 27-28 June. The Aviation Color Code was raised to Orange.
Geologic Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php
Nevado del Ruiz | Colombia | 4.892°N, 75.324°W | Summit elev. 5279 m
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 28 June-4 July seismicity at Nevado del Ruiz slightly decreased. Significant amounts of water vapor and gas rose from the crater during the week. A gas, steam, and ash plume rose 850 m above the crater rim and drifted NW on 28 June. The Alert Level remained at III (Yellow; the second lowest level on a four-color scale).
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 domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. 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.
Source: Servicio Geológico Colombiano (SGC) http://www.ingeominas.gov.co/
Popocatepetl | Mexico | 19.023°N, 98.622°W | Summit elev. 5426 m
During 29 June-5 July the seismic network at Popocatépetl detected 128-193 daily emissions and as many as five daily explosions. Cloud cover often prevented observations, although crater incandescence was visible every night. Explosions at 1348 and 1405 on 4 July produced ash plumes that rose 1.5 and 1.2 km above the crater, respectively. Ashfall was reported in Atlatlahucan (30 km WSW) and Tepetlixpa (20 km W). The Alert Level remained at Yellow, Phase Two.
Geologic Summary. Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major plinian eruptions, the most recent of which took place about 800 CE, have occurred from Popocatépetl since the mid Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since precolumbian time.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED) http://www.cenapred.unam.mx/es/
Ruapehu | North Island (New Zealand) | 39.28°S, 175.57°E | Summit elev. 2797 m
On 5 July GeoNet reported that the elevated activity at Ruapehu had declined; gas emissions returned to baseline levels, volcanic tremor decreased to levels detected in the second half of 2015, and the temperature of the summit Crater Lake had declined from a high of 46 to 23 ºC. The Volcanic Alert Level was lowered to 1 (minor volcanic unrest) and the Aviation Colour Code was lowered to Green.
Geologic Summary. Ruapehu, one of New Zealand's most active volcanoes, is a complex stratovolcano constructed during at least four cone-building episodes dating back to about 200,000 years ago. The 110 cu km dominantly andesitic volcanic massif is elongated in a NNE-SSW direction and surrounded by another 100 cu km ring plain of volcaniclastic debris, including the Murimoto debris-avalanche deposit on the NW flank. A series of subplinian eruptions took place between about 22,600 and 10,000 years ago, but pyroclastic flows have been infrequent. A single historically active vent, Crater Lake, is located in the broad summit region, but at least five other vents on the summit and flank have been active during the Holocene. Frequent mild-to-moderate explosive eruptions have occurred in historical time from the Crater Lake vent, and tephra characteristics suggest that the crater lake may have formed as early as 3000 years ago. Lahars produced by phreatic eruptions from the summit crater lake are a hazard to a ski area on the upper flanks and to lower river valleys.
Source: GeoNet http://www.geonet.org.nz/
Santa Maria | Guatemala | 14.756°N, 91.552°W | Summit elev. 3772 m
CONRED reported that an explosion at 1002 on 29 June at Caliente cone, part of Santa María's Santiaguito lava-dome complex, generated pyroclastic flows, and an ash plume that rose 2.5 km above the crater and drifted W and SW. Ash fell in El Faro. The report noted that more than 60 explosions had been detected so far this year. A strong explosion at 0920 on 1 July produced an ash plume that rose 2.5 km and drifted SW. A pyroclastic flow descended the S flank. Ashfall was reported in San Marcos Palajunoj, Loma Linda, San Martín Chile Verde, and Malacatán. A loud explosion in the evening of 2 July was followed by pyroclastic flows that descended the SW flanks. A 30-m-wide hot lahar triggered by rainfall descended the Nimá I and Cabello de Ángel drainages on 3 July, carrying rocks up to 1.5 m in diameter.
Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive 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, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that during 24 June-1 July lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a thermal anomaly over the dome. 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
Sinabung | Indonesia | 3.17°N, 98.392°E | Summit elev. 2460 m
Based on PVMBG ground-based observations, satellite images, and webcam views, the Darwin VAAC reported that during 29 June-5 July ash plumes from Sinabung rose to altitudes of 3.4-5.5 km (11,000-18,000 ft) a.s.l. and drifted in multiple directions. On 3 July BNPB reported that the eruption at Sinabung continued at a very high level. Lava was incandescent as far as 1 km down the SE and E flanks, and multiple avalanches were detected. An explosion at 1829 generated an ash plume that rose 1.5 km and drifted E and SE, causing ashfall in Medan (55 km NE). The Alert Level remained at 4 (on a scale of 1-4), with an exclusion zone of 7 km from the volcano on the SSE sector, and 6 km in the ESE sector, and 4 km in the NNE sector. There were 2,592 families (9,319 people) displaced to nine shelters, and an additional 1,683 families in temporary shelters waiting for relocation.
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.
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/
Turrialba | Costa Rica | 10.025°N, 83.767°W | Summit elev. 3340 m
OVSICORI-UNA reported increased tremor at Turrialba that began at 2125 on 28 June, likely coinciding with a gas-and-ash emission. Another signal at 2159 also likely coincided with an ash emission. No activity was observed with the webcam, although it was dark and cloudy. Activity had significantly decreased by 0800 on 30 June. Seismicity remained low through 5 July with only a few low-frequency earthquakes detected. Gas emissions were mostly comprised of water vapor.
Geologic Summary. Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/
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