Smithsonian / USGS Weekly Volcanic Activity Report 15-21 June 2016
*****************************************************************************************************
Smithsonian / USGS Weekly Volcanic Activity Report
15-21 June 2016
Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)
URL: http://www.volcano.si.edu/reports_weekly.cfm
New Activity/Unrest: Bulusan, Luzon (Philippines) | Kanlaon, Philippines | Okataina, North Island (New Zealand) | Pacaya, Guatemala | San Miguel, El Salvador | Santa Maria, Guatemala
Ongoing Activity: Alaid, Kuril Islands (Russia) | Awu, Sangihe Islands (Indonesia) | Bagana, Bougainville (Papua New Guinea) | Bristol Island, South Sandwich Islands (UK) | Chirpoi, Kuril Islands (Russia) | Dukono, Halmahera (Indonesia) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Kuchinoerabujima, Ryukyu Islands (Japan) | Makian, Halmahera (Indonesia) | Pavlof, United States | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Tengger Caldera, Eastern Java (Indonesia) | Turrialba, Costa Rica | 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
Bulusan | Luzon (Philippines) | 12.77°N, 124.05°E | Summit elev. 1565 m
PHIVOLCS reported that a seven-minute-long phreatic explosion at Bulusan began at 1303 on 19 June, and generated a dirty white ash plume that rose 300 m and drifted NW. The Alert Level remained at 1, indicating abnormal conditions and a 4-km-radius Permanent Danger Zone (PDZ).
Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. Bulusan lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of 1565-m-high Bulusan volcano is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
Kanlaon | Philippines | 10.412°N, 123.132°E | Summit elev. 2435 m
Based on visual observations, PHIVOLCS reported that a series of three eruptive events occurred at Kanlaon on 18 June, beginning at 0919 and lasting 27 minutes. These events were recorded by the seismic monitoring network as consecutive explosion-type earthquakes that lasted 30, 42, and 29 seconds, respectively. The first event, a steam-and-gas explosion, generated a light gray-to-white ash plume that rose 1.5 km above the crater and then later to 3 km. The second event, an ash eruption immediately following the first event, produced a dense black ash plume that rose 500 m. Lastly, a grayish ash plume rose 500 m. Minor ashfall was reported to the W in the barangays of Ara-al, San Miguel, and Yubo in La Carlota City (14 km W), Sag-ang in La Castellana (16 km SW), and Ilijan in Bago City (30 km NW). A diffuse sulfur odor was detected in Ara-al. The Alert Level remained at 1 (on a scale of 0-5).
Geologic Summary. Kanlaon volcano (also spelled Canlaon), the most active of the central Philippines, forms the highest point on the island of Negros. The massive 2435-m-high andesitic stratovolcano is dotted with fissure-controlled pyroclastic cones and craters, many of which are filled by lakes. The largest debris avalanche known in the Philippines traveled 33 km to the SW from Kanlaon. The summit of Kanlaon contains a 2-km-wide, elongated northern caldera with a crater lake and a smaller, but higher, historically active vent, Lugud crater, to the south. Historical eruptions from Kanlaon, recorded since 1866, have typically consisted of phreatic explosions of small-to-moderate size that produce minor ashfalls near the volcano.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/
Okataina | North Island (New Zealand) | 38.12°S, 176.5°E | Summit elev. 1111 m
GeoNet reported that the Mud Rift feature at Okataina's Waimangu Geothermal area erupted during 17-20 May, the first time since 1989. The Mud Rift geothermal vent formed in 1906 in the Raupo Pond Crater (one of multiple craters which formed in June 1886) and is 36 m long, 5-6 m wide, and 15 m deep. The steam-driven events mostly ejected fine sand and mud, and there was abundant evidence of fluids flooding into the rift, especially at the W end. Nearby vegetation was brown, and there was some evidence of collapse around the edges of the vents.
Geologic Summary. The massive, dominantly rhyolitic Okataina Volcanic Centre is surrounded by extensive ignimbrite and pyroclastic sheets produced during multiple caldera-forming eruptions. Numerous lava domes and craters erupted from two subparallel NE-SW-trending vent lineations form the Haroharo and Tarawera volcanic complexes. Lava domes of the Haroharo complex, at the northern end of the Okataina Volcanic Centre, occupy part of the 16 x 26 km Pleistocene Haroharo caldera, which formed incrementally between 300,000 and 50,000 years before present (BP). The oldest exposed rocks on the caldera floor are about 22,000 years old. The Tarawera complex at the southern end of Okataina consists of 11 rhyolitic lava domes and associated lava flows. The oldest domes were formed as late as about 15,000 years BP, and the youngest were formed in the Kaharoa eruption about 800 years BP. The NE-SW Tarawera vent lineation extends from the two dacitic cones of Maungaongaonga and Mangakakaramea on the SW to Mount Edgecumbe on the NE. Construction of the Haroharo and Tarawera complexes impounded lakes Rotoiti, Totoehu, Okataina, and Tarawera against the outer margins of the Okataina ring structure. A major hydrothermal area is located at Waimangu; the world-renowned Pink and White Terrace siliceous sinter deposits were destroyed during the major basaltic explosive eruption of 1886.
Source: GeoNet http://www.geonet.org.nz/
Pacaya | Guatemala | 14.381°N, 90.601°W | Summit elev. 2552 m
On 15 June CONRED reported that activity at Pacaya had increased, characterized by an increase in seismic amplitude, signals indicating explosions, and nighttime crater incandescence; based on INSIVUMEH notices, the activity continued through 23 June.
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.
Sources: Coordinadora Nacional para la Reducción de Desastres (CONRED) http://conred.gob.gt/;
Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
San Miguel | El Salvador | 13.434°N, 88.269°W | Summit elev. 2130 m
SNET reported that at 0800 on 15 June seismicity at San Miguel dramatically increased and remained elevated. At 0410 on 18 June a small explosion occurred in the central crater, ejecting tephra onto the flanks near the crater, and causing ashfall in areas to the NW. Voluminous gas emissions were visible drifting SW during 19-20 June, and local residents on the W and SW flanks reported a sulfur odor.
Geologic Summary. The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit of the 2130-m-high volcano rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit, also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the north, NE, and SE sides. The SE-flank lava flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.
Source: Servicio Nacional de Estudios Territoriales (SNET) http://www.snet.gob.sv/
Santa Maria | Guatemala | 14.756°N, 91.552°W | Summit elev. 3772 m
In a special report posted on 19 June, INSIVUMEH reported that a strong explosion at Caliente cone, part of Santa María's Santiaguito lava-dome complex, occurred at 0512 and generated pyroclastic flows and an ash plume that rose 5 km and drifted 40-50 km W, SW, and S. Ashfall was reported in multiple farms and towns including San Marcos (10 km SW), Loma Linda, Palajunoj (18 km SSW), El Faro (SW flank), Patzulin (SW flank), El Patrocinio, El Palmar (12 km S), San Felipe (15 km SSW), and Las Marías. A loud explosion at 2239 on 20 June generated an ash plume containing lightning that rose 2.5 km. Shock waves were detected in areas within 15 km. Pyroclastic flows traveled 2 km down the W, S, and E sides of Caliente cone. Abundant gas emissions were visible the next day.
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/
Ongoing Activity
Alaid | Kuril Islands (Russia) | 50.861°N, 155.565°E | Summit elev. 2285 m
KVERT reported that moderate activity at Alaid continued during 10-17 June. Satellite images showed a thermal anomaly over the volcano during 9, 11, and 13-14 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
Awu | Sangihe Islands (Indonesia) | 3.67°N, 125.5°E | Summit elev. 1320 m
PVMBG reported that the number of earthquakes at Awu had risen significantly on 11 May and remained elevated through 14 May; a downward trend in seismicity became evident on 21 May. Earthquake hypocenters were located at depths between 1 and 2 km. The Alert Level was lowered to 2 (on a scale of 1-4) on 14 June; residents and tourists were advised to stay 4 km away from the crater.
Geologic Summary. The massive Gunung Awu stratovolcano occupies the northern end of Great Sangihe Island, the largest of the Sangihe arc. Deep valleys that form passageways for lahars dissect the flanks of the volcano, which was constructed within a 4.5-km-wide caldera. Powerful explosive eruptions in 1711, 1812, 1856, 1892, and 1966 produced devastating pyroclastic flows and lahars that caused more than 8000 cumulative fatalities. Awu contained a summit crater lake that was 1 km wide and 172 m deep in 1922, but was largely ejected during the 1966 eruption.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://www.vsi.esdm.go.id/
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 on 16 June ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted over 45 km W.
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/
Bristol Island | South Sandwich Islands (UK) | 59.017°S, 26.533°W | Summit elev. 1100 m
The Buenos Aires VAAC reported that on 16 June a diffuse ash plume from Bristol Island's Mt. Sourabaya was visible in satellite images rising to an altitude of 1.5 km (5,000 ft) a.s.l. and drifting SE. The report noted low confidence in the plume altitude due to weather clouds in the area.
Geologic Summary. The 9 x 10 km Bristol Island near the southern end of the South Sandwich arc lies across Fortser's Passage from the Southern Thule Islands and forms one of the largest islands of the chain. Largely glacier-covered, it contains a horseshoe-shaped ridge at the interior extending northward from the highest peak, 1100-m-high Mount Darnley. A steep-sided flank cone or lava dome, Havfruen Peak, is located on the east side, and a young crater and fissure are on the west flank. Three large sea stacks lying off Turmoil Point at the western tip of the island may be remnants of an older now-eroded volcanic center. Both summit and flank vents have been active during historical time. The latest eruption, during 1956, originated from the west-flank crater, and deposited cinder over the icecap. The extensive icecap and the difficulty of landing make it the least explored of the South Sandwich Islands.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.smn.gov.ar/vaac/buenosaires/productos.php
Chirpoi | Kuril Islands (Russia) | 46.525°N, 150.875°E | Summit elev. 742 m
SVERT reported that a thermal anomaly over Snow, a volcano of Chirpoi, was detected in satellite images on 19 June. 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
Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 15-16 and 18-20 June ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 120 km W, WNW, and 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 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/
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
HVO reported that during 15-21 June the lava lake continued to rise and fall, circulate, and spatter in Kilauea's Overlook vent. 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. An active lava pond in Pu'u 'O'o's W pit was confirmed by observers on 16 June.
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/
Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m
KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 10-17 June. Satellite and video data showed a lava flow continuing to effuse on the SE flank. Satellite images showed an intense thermal anomaly over the volcano, and an ash plume drifting almost 50 km W on 13 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
Kuchinoerabujima | Ryukyu Islands (Japan) | 30.443°N, 130.217°E | Summit elev. 657 m
On 14 June JMA reported that no activity at Kuchinoerabujima had been detected after a small eruption on 19 June 2015. The report noted that volcanic tremor had not been detected, the temperature of thermal areas had declined, sulfur dioxide gas flux was lower than values detected prior to the May-June 2015 eruption, and volcanic earthquake levels were lower than levels detected in August 2014. The Alert Level was lowered to 3 (the highest level on a 1-5 scale) on 14 June, and the public was reminded to stay at least 2 km away from Shindake Crater.
Geologic Summary. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyus, 15 km west of Yakushima. Furutake, Shintake, and Noike were erupted from south to north, respectively, to form a composite cone that is parallel to the trend of the Ryukyu Islands. The highest peak, Furutake, reaches only 657 m above sea level. The youngest cone, 640-m-high Shintake, was formed after the NW side of Furutake was breached by an explosion. All historical eruptions have occurred from Shintake, although a lava flow from the S flank of Furutake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shintake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.
Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/
Makian | Halmahera (Indonesia) | 0.32°N, 127.4°E | Summit elev. 1357 m
PVMBG reported that during 1 January-15 June gas plumes from Makian rose no higher than the crater rim. Seismicity fluctuated but decreased overall. On 16 June the Alert Level was lowered to 1 (on a scale of 1-4).
Geologic Summary. Makian volcano forms a 10-km-wide island near the southern end of a chain of volcanic islands off the west coast of Halmahera and has been the source of infrequent, but violent eruptions that have devastated villages on the island. The large 1.5-km-wide summit crater, containing a small lake on the NE side, gives the peak a flat-topped profile. Two prominent valleys extend to the coast from the summit crater on the north and east sides. Four parasitic cones are found on the western flanks. Eruption have been recorded since about 1550; major eruptions in 1646, 1760-61, 1861-62, 1890, and 1988 caused extensive damage and many fatalities.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://www.vsi.esdm.go.id/
Pavlof | United States | 55.417°N, 161.894°W | Summit elev. 2493 m
AVO reported that activity at Pavlof had returned to baseline levels following a brief eruptive period in mid-May; minor ash emissions were last observed on 16 May. On 17 June AVO lowered the Aviation Color Code to Green and Volcano Alert Level to Normal.
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/
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that during 10-17 June lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed an intense 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 satellite and webcam images, and information from PVMBG, the Darwin VAAC reported that during 19-20 June ash plumes from Sinabung rose to altitudes of 4.3-4.6 km (14,000-15,000 ft) a.s.l. and drifted SE and E.
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: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/anon/gen/vaac/
Tengger Caldera | Eastern Java (Indonesia) | 7.942°S, 112.95°E | Summit elev. 2329 m
Based on satellite images, wind data, and information from PVMBG, the Darwin VAAC reported that on 21 June ash plumes from Tengger Caldera's Bromo cone rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted almost 20 km S and SE.
Geologic Summary. The 16-km-wide Tengger caldera is located at the northern end of a volcanic massif extending from Semeru volcano. The massive volcanic complex dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes, each truncated by a caldera. Lava domes, pyroclastic cones, and a maar occupy the flanks of the massif. The Ngadisari caldera at the NE end of the complex formed about 150,000 years ago and is now drained through the Sapikerep valley. The most recent of the calderas is the 9 x 10 km wide Sandsea caldera at the SW end of the complex, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most active and most frequently visited volcanoes.
Source: 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 that high-amplitude tremor at Turrialba began at 0145 on 16 June, accompanied by passive ash-and-gas emissions that rose 500 m above the crater. Tremor and emissions ceased at 0715. Emissions of ash and gas were again observed at 0805, for a brief 10-minute period, and at 1557. A vapor plume with minor amounts of ash was visible at 1700. On 19 June tremor began at 0410, along with passive ash-and-gas emissions that rose 500 m above the crater and drifted NW. Tremor significantly decreased at 0825. Tremor signals recorded at 1158 on 20 June indicated ash emissions; the wind direction was NW.
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/
Zhupanovsky | Eastern Kamchatka (Russia) | 53.589°N, 159.15°E | Summit elev. 2899 m
KVERT reported that no activity was observed at Zhupanovsky after an explosion on 24 March, and the last thermal anomaly detection in a satellite image was on 1 April. The Aviation Color Code was lowered to Green on 16 June.
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
Volcano Listserv is a collaborative venture among Arizona State University (ASU), Portland State University (PSU), the Global Volcanism Program (GVP) of the Smithsonian Institution's National Museum of Natural History, and the International Association for Volcanology and Chemistry of the Earth's Interior (IAVCEI).
ASU - http://www.asu.edu/ PSU - http://pdx.edu/ GVP - http://www.volcano.si.edu/ IAVCEI - http://www.iavcei.org/
To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxx.
To contribute to the volcano list, send your message to: volcano@xxxxxxx. Please do not send attachments.
==============================================================
