26 May-1 June 2010
Sally Kuhn Sennert - Weekly Report Editor
kuhns@xxxxxx
URL: http://www.volcano.si.edu/reports/usgs/
New Activity/Unrest: | Arenal, Costa Rica | Bezymianny, Central Kamchatka (Russia) | Cleveland, Chuginadak Island | Kirishima, Kyushu | Pacaya, Guatemala | Pagan, Mariana Islands (Central Pacific) | Sarigan, Mariana Islands (Central Pacific) | Tungurahua, Ecuador | Ulawun, New Britain | Yasur, Vanuatu (SW Pacific)
Ongoing Activity: | Alaid, Kuril Islands (Russia) | Bagana, Bougainville | Eyjafjallajökull, Southern Iceland | Fuego, Guatemala | Gaua, Banks Islands (SW Pacific) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) | Kliuchevskoi, Central Kamchatka (Russia) | Reventador, Ecuador | Santa María, Guatemala | Sarychev Peak, Matua Island | Shiveluch, Central 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
ARENAL Costa Rica 10.463°N, 84.703°W; summit elev. 1670 m
OVSICORI-UNA reported that on 24 May a series of incandescent flows descended the W flank, towards the lake, reaching the forest. An ash plume drifted N. Arenal National Park was closed briefly due to the activity.
Geologic Summary. Conical Volcan Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1,657-m-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. The earliest known eruptions of Arenal took place about 7,000 years ago. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/
BEZYMIANNY Central Kamchatka (Russia) 55.978°N, 160.587°E; summit elev. 2882 m
KVERT reported that some earthquakes were detected in the vicinity of Bezymianny's lava dome during 23-24 May, even though much of the seismicity was obscured by strong activity from Kliuchevskoi. Fumarolic activity was seen on 21 May. The temperature of the thermal anomaly detected in satellite imagery increased from 18 degrees Celsius on 19 May to 48.8 degrees Celsius on 23 May. The Aviation Color Code level was raised to Orange. During 21-28 May satellite data showed a variable but daily thermal anomaly over the lava dome. Fumarolic activity was occasionally detected, and another seismic event was recorded on 24 May.
Seismic data indicated that an explosive eruption began on 1 June, producing a large ash cloud about 127 by 93 km in dimension. The Aviation Color Code level was raised to Red. Further analyses showed that ash plumes from two explosions rose to altitudes of 8-10 km (26,200-32,800 ft) a.s.l. and drifted at first 250 km W and then 160 km N and NE. Ashfall was reported in Kozyrevsk village, 45 km W. Two bright thermal anomalies were seen in satellite imagery, possibly from pyroclastic flow deposits. The next day, strong gas-and-steam emissions rose from the lava dome. The Aviation Color Code level was lowered to Orange.
Geologic Summary. Prior to its noted 1955-56 eruption, Bezymianny volcano had been considered extinct. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. That eruption, similar to the 1980 event at Mount St. Helens, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml
CLEVELAND Chuginadak Island 52.825°N, 169.944°W; summit elev. 1730 m
AVO reported a small ash emission from Cleveland on 30 May. A detached plume seen in satellite imagery rose no higher than 4.9 km (16,000 ft) a.s.l. and drifted SW. Satellite images the next day revealed minor (uncharacterized) flow deposits on the upper flanks. The Volcano Alert Level remained at Advisory and the Aviation Color Code remained at Yellow.
Geologic Summary. Symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited dumbbell-shaped Chuginadak Island in the east-central Aleutians. The 1,730-m-high stratovolcano is the highest of the Islands of Four Mountains group and is one of the most active in the Aleutians. Numerous large lava flows descend its flanks. It is possible that some 18th to 19th century eruptions attributed to Carlisle (a volcano located across the Carlisle Pass Strait to the NW) should be ascribed to Cleveland. In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions from Mt. Cleveland have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.
Source: Alaska Volcano Observatory (AVO) http://www.avo.alaska.edu/
KIRISHIMA Kyushu 31.931°N, 130.864°E; summit elev. 1700 m
According to JMA, a small eruption from Shinmoe-dake (Shinmoe peak), a stratovolcano of the Kirishima volcano group, on 27 May produced an ash plume that rose 100 m above the crater rim. Ashfall was noted in areas within 6 km. Emissions gradually decreased.
Geologic Summary. Kirishima is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene volcano group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1,700-m-high Karakuni-dake being the highest. Onami-ike and Mi-ike, the two largest maars, are located SW of Karakuni-dake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Mi-ike to Ohachi, and at Shinmoe-dake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.
Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/indexe.html
PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m
A Strombolian eruption from Pacaya's MacKenney cone that began on 27 May was characterized in a report from CONRED as having constant explosions that ejected material 500 m into the air. Ash plumes rose 1.5 km above the crater and drifted W and SW, causing ashfall in multiple areas. The community of El Patrocinio (about 5 km W) evacuated and residents in El Rodeo (4 km WSW) were ordered to evacuate. Due to extensive tephra fall, authorities recommended that residents clean off ash from their roofs and refrain from driving.
INSIVUMEH reported a continuing series of explosions 5-10 seconds apart that ejected black ash up to 1 km above the crater on 28 May. Seismic signals reflected the explosions in addition to tremor. Ash plumes drifted 20-30 km NW, causing ashfall in areas downwind, including in Guatemala City, about 30 km NNE. CONRED reported a short time later that about 1,600 people had been evacuated from six towns 3-4 km W, NNW, N, and NNE, and that Aurora International Airport was closed. According to a map posted by CONRED, blocks fell in areas as far away as 12 km NE and ash was reported in areas E of Chinautla, 37 km NNE. News media reported that one person (a reporter) died and three children were missing.
On 29 May, a 90-m-wide lava flow that traveled SSE at an estimated rate of 100 m per hour burned three houses on the Pacaya Grande ranch. The lava was within 450 m of some other properties including El Chupadero, located 2-2.5 km S of the crater, and disrupted an access road from El Caracol (3 km SW) and Los Pocitos (5.5 km S). Explosions ejected ash 300-500 m above the crater. INSIVUMEH reported on 1 June that the Strombolian activity continued. Explosions ejected ash as high as 700 m above the crater and ash plumes drifted NW. Two lava flows were seen traveling SW and SE.
Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 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. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://conred.gob.gt/,
Coordinadora Nacional para la Reducción de Desastres (CONRED) http://conred.gob.gt/,
Reuters http://www.timeslive.co.za/world/article475245.ece/Guatemala-volcano-shuts-airport-kills-one
PAGAN Mariana Islands (Central Pacific) 18.13°N, 145.80°E; summit elev. 570 m
Gas-and-steam plumes from Pagan continued to be observed in satellite imagery during 21-28 May. Reports from researchers camped on the island, and imagery analyses, suggested that trace amounts of ash were intermittently present in the plumes during 23-26 May. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Geologic Summary. Pagan Island, the largest and one of the most active of the Marianas Islands volcanoes, consists of two stratovolcanoes connected by a narrow isthmus. Both North and South Pagan stratovolcanoes were constructed within calderas, 7 and 4 km in diameter, respectively. The 570-m-high Mount Pagan at the NE end of the island rises above the flat floor of the caldera, which probably formed during the early Holocene. South Pagan is a 548-m-high stratovolcano with an elongated summit containing four distinct craters. Almost all of the historical eruptions of Pagan, which date back to the 17th century, have originated from North Pagan volcano. The largest eruption of Pagan during historical time took place in 1981 and prompted the evacuation of the sparsely populated island.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands, Office of the Governor, United States Geological Survey Volcano Hazards Program http://volcanoes.usgs.gov/nmi/activity/index.php
SARIGAN Mariana Islands (Central Pacific) 16.708°N, 145.78°E; summit elev. 538 m
On 27 May an observer from the Emergency Management Office (EMO) in Saipan photographed an area of discolored ocean water and possible light-colored floating material about 7 km S of Sarigan during an overflight. The area was about 1.6 km long, although the scale was difficult to discern from photographs. Two days later, the area of affected water was about twice the size of Sarigan Island. According to a news article, U.S. Fish and Wildlife evacuated 16 people, mostly scientists, to Saipan from a few area islands, including eight people from Sarigan.
On 30 May a plume of mostly water vapor was seen in satellite imagery rising to a possible altitude of 12.2 km (40,000 ft) a.s.l. and dissipating as it drifted S. The eruption was attributed to a 300-m-deep submarine vent on Sarigan's S flank, about 7 km from the island. Observers on Sarigan reported hearing a loud explosion from the S, and shortly thereafter received ashfall. The Volcano Alert Level was raised to Watch and the Aviation Color Code was raised to Orange. Both seismicity at a single nearby station on Sarigan and subaqueous activity declined after the plume emission. The next day the Volcano Alert Level was reduced to Advisory and the Aviation Color Code was reduced to Yellow.
Geologic Summary. Sarigan volcano forms a 3-km-long, roughly triangular island. A low truncated cone with a 750-m-wide summit crater contains a small ash cone. The youngest eruptions produced two lava domes from vents above and near the S crater rim. Lava flows from each dome reached the coast and extended out to sea, forming irregular shorelines. The northern flow overtopped the crater rim on the N and NW sides. The sparse vegetation on the flows indicates they are of Holocene age.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands and the US Geological Survey Hawaiian Volcano Observatory http://volcanoes.usgs.gov/nmi/activity/index.php,
Saipan Tribune http://www.saipantribune.com/newsstory.aspx?newsID=100114&cat=1
TUNGURAHUA Ecuador 1.467°S, 78.442°W; summit elev. 5023 m
The IG reported that on 26 May a strong explosion from Tungurahua generated pyroclastic flows and an ash plume that rose to an altitude of 12 km (39,400 ft) a.s.l. and drifted W and SW. Ashfall was reported in areas to the S and SW, including Riobamba (30 km S). Noises resembling "cannon shots" associated with the explosion were heard as far away as Guadalupe, 11 km N. The pyroclastic flows were small and traveled 800-1,000 m down the N, NW, W, and SW flanks; they did not reach populated areas. Poor visibility mostly prevented observations of the crater the next day, but no activity was seen when the crater was visible. Slight ashfall was reported in Cahuají.
On 28 May another strong explosion produced an ash plume that rose to an altitude of 15 km (49,200 ft) a.s.l. and drifted WSW. Pumice blocks fell in local neighborhoods (likely 6-8 km away), and ash fell in several areas between Tungurahua and Guayaquil (about 180 km SW), and beyond. Pyroclastic flows traveled as far as 3 km down the NW, W, and SW flanks, but again did not reach populated areas. According to news articles, residents from two towns about 8 km NW were evacuated and the airport in Guayaquil was temporarily closed because the runways were covered in ash. Other flights passing through the area were rerouted.
During 28-29 May seismicity increased and 5-10 explosions were detected per hour. Explosions ejected incandescent blocks that fell 1-2 km below the summit. Ashfall was heavy in Runtún, 6 km NNE, at night on 28 May, and lighter in Juive and Puntzán, 7 km NW, the next morning. During 29-30 May explosions occurred at a rate of about 10 per hour. Several roaring noises were noted and "cannon shot" noises caused large windows nearby to vibrate. Incandescence around the crater was seen occasionally at night, during periods of clearer viewing. On 31 May and 1 June explosions generated audible "cannon shots" and ejected incandescent blocks as high as 1.5 km above the crater rim; several of the blocks rolled nearly 1 km down the flanks. Steam-and-ash plumes rose to altitudes of 7-9 km (23,000-29,500 ft) a.s.l. and drifted W, SW, N, and NE, causing ashfall in areas downwind.
Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/,
Reuters http://thestar.com.my/news/story.asp?file=/2010/5/29/worldupdates/2010-05-29T032927Z_01_NOOTR_RTRMDNC_0_-488970-1&sec=Worldupdates
ULAWUN New Britain 5.05°S, 151.33°E; summit elev. 2334 m
RVO reported that during 22-28 May Ulawun emitted thick white vapor plumes that rose 800 m high. Some areas of the plumes were gray on 22 and 25 May. People on the S and SE sides of the island heard "low jetting" noises during 24-25 May. Weak and fluctuating incandescence was seen at night during 28-29 May by people on the S part of the island. The emissions changed color to gray on 29 May and continued similarly the next two days. On 30 May very fine ashfall was reported in areas to the SSW, S, and SSE. On 1 and 2 June only white vapor emissions were noted. RVO recommended to the WNB Provincial Disaster Committee to declare a Stage 1 Alert to reflect an increasing trend of seismic energy, and a recent presence of occasional gray plumes, incandescence, and audible noises from Ulawun.
Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Source: Rabaul Volcano Observatory (RVO)
YASUR Vanuatu (SW Pacific) 19.53°S, 169.442°E; summit elev. 361 m
The Vanuatu Geohazards Observatory reported that the Vanuatu Volcano Alert Level (VVAL) for Yasur was increased to 3 (on a scale of 0-4) on 27 May. Recent activity was characterized by moderate to large eruptions with strong explosions, ejected bombs that fell on the visitor viewing area, and significant ashfall in nearby villages. Visitors were not allowed to enter a restricted zone, within about 500 m around the volcano. Activity had been escalating since January 2010. According to a news article, an eruption plume on 1 June rose to an altitude of 1.8 km (6,000 ft) a.s.l. and spread over 340 square kilometers, canceling or delaying some flights in and out of New Caledonia (about 430 km WSW).
Geologic Summary. Yasur, the best-known and most frequently visited of the Vanuatu volcanoes, has been in more-or-less continuous Strombolian and vulcanian activity since Captain Cook observed ash eruptions in 1774. This style of activity may have continued for the past 800 years. Yasur is a mostly unvegetated pyroclastic cone with a nearly circular, 400-m-wide summit crater. Yasur is largely contained within the small Yenkahe caldera in SE Tanna Island. It is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. Active tectonism along the Yenkahe horst accompanying eruptions of Yasur has raised Port Resolution harbor more than 20 m during the past century.
Sources: Vanuatu Geohazards Observatory http://www.geohazards.gov.vu/,
Agence France-Presse http://www.google.com/hostednews/afp/article/ALeqM5ibYovadURnETqAD0Vx2BWnx66m8Q,
Radio New Zealand International http://www.rnzi.com/pages/news.php?op=read&id=53881
Ongoing Activity
ALAID Kuril Islands (Russia) 50.858°N, 155.55°E; summit elev. 2339 m
KVERT reported that on 23 May a gas-and-steam plume from Alaid was seen in satellite imagery drifting 11 km ESE. No other signs of possible increasing activity were seen in imagery or noted by observers on Paramushir Island during 21-28 May. KVERT lowered the Aviation Color Code to Green.
Geologic Summary. The highest and northernmost volcano of the Kurile Islands, 2,339-m-high Alaid is a symmetrical stratovolcano when viewed from the N, but has a 1.5-km-wide summit crater that is breached widely to the S. Alaid is the northernmost of a chain of volcanoes constructed W of the main Kuril archipelago and rises 3,000 m from the floor of the Sea of Okhotsk. Numerous pyroclastic cones dot the lower flanks of Alaid, 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 Kurile Islands.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml
BAGANA Bougainville 6.140°S, 155.195°E; summit elev. 1750 m
Based on analyses of satellite imagery, the Darwin VAAC reported that ash plumes from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. during 26-28 May and drifted 30-185 km SW and W.
Geologic Summary. Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is 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.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html
EYJAFJALLAJOKULL Southern Iceland 63.63°N, 19.62°W; summit elev. 1666 m
The Nordic Volcanological Center (NVC) at the Institute of Earth Sciences reported that on 26 May steam plumes from Eyjafjallajökull rose to an altitude of 2 km (6,600 ft) a.s.l. and drifted S. The crater was not seen through the web cameras due to poor visibility from remobilized, blowing ash. Scientists conducted an expedition to the summit crater the next day. They measured the tephra deposits around the E half of the craters, and found that they were about 40 m thick closest to the craters. Steam rose from the crater, punctuated by a few small ash-bearing explosions, and a sulfur odor was strong nearby. On 31 May and 1 June, widespread drifting of existing ash was noted in SW Iceland. Meteorological clouds prevented views of the summit craters.
Geologic Summary. Eyjafjallajökull (also known as Eyjafjöll) is located west of Katla volcano. Eyjafjallajökull consists of an E-W-trending, elongated ice-covered basaltic-andesite stratovolcano with a 2.5-km-wide summit caldera. Fissure-fed lava flows occur on both the eastern and western flanks of the volcano, but are more prominent on the western side. Although the 1666-m-high volcano has erupted during historical time, it has been less active than other volcanoes of Iceland's eastern volcanic zone, and relatively few Holocene lava flows are known. An intrusion beneath the south flank from July-December 1999 was accompanied by increased seismic activity and was constrained by tilt measurements, GPS-geodesy and InSAR. The last historical eruption of Eyjafjallajökull prior to an eruption in 2010 produced intermediate-to-silicic tephra from the central caldera during December 1821 to January 1823.
Source: Institute of Earth Sciences http://www.earthice.hi.is/
FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m
INSIVUMEH reported on 29 May that abundant rains from tropical storm Agatha triggered lahars in ravines to Fuego's SW and SE.
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 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
GAUA Banks Islands (SW Pacific) 14.27°S, 167.50°E; summit elev. 797 m
Based on information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported that on 26 May an ash plume from Gaua rose to an altitude of 3 km (10,000 ft) a.s.l.
Geologic Summary. The roughly 20-km-diameter Gaua Island, also known as Santa Maria, consists of a basaltic-to-andesitic stratovolcano with an 6 x 9 km wide summit caldera. Small parasitic vents near the caldera rim fed Pleistocene lava flows that reached the coast on several sides of the island; several littoral cones were formed where these lava flows reached the sea. Quiet collapse that formed the roughly 700-m-deep caldera was followed by extensive ash eruptions. Construction of the historically active cone of Mount Garat (Gharat) and other small cinder cones in the SW part of the caldera has left a crescent-shaped caldera lake. The symmetrical, flat-topped Mount Garat cone is topped by three pit craters. The onset of eruptive activity from a vent high on the SE flank of Mount Garat in 1962 ended a long period of dormancy.
Source: Wellington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/NZ/messages.html
KARYMSKY Eastern Kamchatka (Russia) 54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that during 21-28 May seismic activity from Karymsky was above background levels, suggesting that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. Satellite imagery revealed a daily thermal anomaly over the volcano, and ash plumes that drifted 63 km S and W during 24-26 May. The Aviation Color Code level remained at Orange.
Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml
KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m
During 26 May-1 June HVO reported that activity at Kilauea continued from the summit and the east rift zone. At the summit, the level of the circulating, crusting, and bubbling lava-pool surface remained mostly stable in the deep pit inset within the floor of Halema'uma'u crater; glow from the vent was visible. On 31 May the surface rose to the highest level yet recorded, but was still more than 100 m below the Halema'uma'u crater floor.
At the east rift zone, lava flows that broke out of the TEB lava-tube system had advanced down the Pulama pali onto the coastal plain and headed S, entering the ocean at Ki. Other lava flows were active above the pali. On 27 May geologists noted a small rootless shield building up at a break-out point at 580 m elevation. Small lava flows issued from vents on Pu'u 'O'o's S crater wall during 26-27 May, and pooled on the crater floor at least through 31 May.
Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m
KVERT reported that during 21-28 May seismic activity from Kliuchevskoi was above background levels and Strombolian activity was seen. Gas-and-steam plumes occasionally containing a small amount of ash were also noted. During 23-26 May observed ash plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. Satellite imagery revealed a large daily thermal anomaly from the volcano, and ash plumes that drifted 185 km in multiple directions on 24 and 26 May. The Aviation Color Code level remained at Orange.
Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 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 major explosive and effusive events from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/updates.shtml
REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m
The IG reported a lahar on Reventador's E flank, detected for 90 minutes by the seismic network on 25 May. It destroyed a bridge over the Marker River, disrupting the route from Baeza to Lago Agrio.
Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/
SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported on 29 May that abundant rains from tropical storm Agatha triggered lahars in Santa Maria's S ravines.
Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/
SARYCHEV PEAK Matua Island 48.092°N, 153.20°E; summit elev. 1496 m
SVERT reported that a thermal anomaly on Sarychev Peak was detected by satellite on 27 May. Sarychev Peak does not have a seismic network; satellite image observations are the primary tool for monitoring many of the Kurile Islands volcanoes.
Geologic Summary. Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5 km wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows descend all sides of Sarychev Peak and often form capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760's and include both quiet lava effusion and violent explosions. The largest historical eruption of Sarychev Peak in 1946 produced pyroclastic flows that reached the sea.
Source: Sakhalin Volcanic Eruption Response Team (SVERT) http://www.imgg.ru/rus/labs_vulcan_hazard.php
SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m
KVERT reported that during 21-28 May seismic activity from Shiveluch was above background levels, suggesting that possible ash plumes rose to an altitude of 4.7 km (15,400 ft) a.s.l. Satellite imagery showed a large daily thermal anomaly, and an ash plume that drifted 10 km NE on 23 May. Observations revealed fumarolic activity, and ash plumes that rose to an altitude of 4.5 km (14,800 ft) a.s.l. on 24 and 25 May. The Aviation Color Code level remained at Orange.
Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
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