6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6 From: "Kuhn, Sally" <KUHNS@xxxxxx> 6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6-6 Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx) URL: https://volcano.si.edu/reports_weekly.cfm New Activity/Unrest: Colima, Mexico | Pavlof, United States | Piton de la Fournaise, Reunion Island (France) | Sangeang Api, Indonesia Ongoing Activity: Agung, Bali (Indonesia) | Aira, Kyushu (Japan) | Azumayama, Honshu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Klyuchevskoy, Central Kamchatka (Russia) | Krakatau, Indonesia | Kuchinoerabujima, Ryukyu Islands (Japan) | Manam, Papua New Guinea | Pacaya, Guatemala | Poas, Costa Rica | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Villarrica, Chile 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, these reports 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 about recent activity are published in issues of the Bulletin of the Global Volcanism Network. Note that many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. New Activity/Unrest Colima | Mexico | 19.514°N, 103.62°W | Summit elev. 3850 m Centro Universitario de Estudios e Investigaciones de Vulcanologia - Universidad de Colima reported that intermittent steam-and-gas emissions mainly from the NE side of the crater and small explosions continued to be recorded during 8-14 June. Weather conditions often prevented visual observations of the crater. 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: Centro Universitario de Estudios e Investigaciones de Vulcanologia - Universidad de Colima http://portal.ucol.mx/cueiv/contacto.htm Pavlof | United States | 55.417°N, 161.894°W | Summit elev. 2493 m On 12 June AVO reported that elevated levels of seismicity at Pavlof, recorded since mid-May, had declined to background levels. The Aviation Color Code was lowered to Green and the Volcano Alert Level was lowered to Normal. The report noted that vapor plumes were occasionally visible in webcam views and elevated surface temperatures in the summit crater were sometimes identified in satellite images; both are common occurrences at Pavlof. 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) https://avo.alaska.edu/ Piton de la Fournaise | Reunion Island (France) | 21.244°S, 55.708°E | Summit elev. 2632 m The eruption at Piton de la Fournaise that began at 0635 on 11 June continued through 12 June from fissures on the SSE flank of Dolomieu Crater. The front of the lava flow had reached around 1,200-1,300 m elevation by 0620. OVPF stated that the eruption ended at 1200 on 13 June. Geologic Summary. The massive Piton de la Fournaise basaltic shield volcano on the French island of Réunion in the western Indian Ocean is one of the world's most active volcanoes. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three calderas formed at about 250,000, 65,000, and less than 5000 years ago by progressive eastward slumping of the volcano. Numerous pyroclastic cones dot the floor of the calderas and their outer flanks. Most historical eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest caldera, which is 8 km wide and breached to below sea level on the eastern side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures on the outer flanks of the caldera. The Piton de la Fournaise Volcano Observatory, one of several operated by the Institut de Physique du Globe de Paris, monitors this very active volcano. Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF) http://www.ipgp.fr/ Sangeang Api | Indonesia | 8.2°S, 119.07°E | Summit elev. 1949 m The Darwin VAAC reported that on 17 June multiple discrete emissions with increasing ash content over a period of about an hour rose from Sangeang Api to altitudes of 1.2-2.1 (4,000-7,000 ft) a.s.l. and drifted W and WNW, based on satellite images and weather models. A thermal anomaly was also visible. The Alert Level remained at 2 (on a scale of 1-4). Geologic Summary. Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, 1949-m-high Doro Api and 1795-m-high Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century. Sources: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml; Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Ongoing Activity Agung | Bali (Indonesia) | 8.343°S, 115.508°E | Summit elev. 2997 m PVMBG reported that an eruption at Agung, recorded by the seismic network at 0138 on 13 June, ejected incandescent material onto the flanks. The Darwin VAAC stated that ash plumes rose to altitudes of 5.5 and 9.1 km (18,000 and 30,000 ft) a.s.l. and drifted W and SW, respectively, based on webcam views and satellite data. By 0635 the ash plume had detached and by 1505 it was about 370 km S of Agung. The Alert Level remained at 3 (on a scale of 1-4) with the exclusion zone set at a 4 km radius. Geologic Summary. Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Aira | Kyushu (Japan) | 31.593°N, 130.657°E | Summit elev. 1117 m JMA reported that inflation at Minamidake crater (at Aira Calderaâ??s Sakurajima volcano) began at 0500 on 11 June. At 1431 an explosion ejected material 1.2 km from the crater and generated an ash plume that rose 2.2 km above the crater rim. An explosion at 0921 on 13 June was followed by some deflation. Very small eruptive events were recorded during 14-17 June. 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/ Azumayama | Honshu (Japan) | 37.735°N, 140.244°E | Summit elev. 1949 m On 17 June JMA lowered the Alert Level for Azumayama to 1 (the lowest level on a 5-level scale), noting that deformation and elevated seismicity recorded in May had stabilized and decreased, respectively. Geologic Summary. The Azumayama volcanic group consists of a cluster of stratovolcanoes, shield volcanoes, lava domes, and pyroclastic cones. The andesitic and basaltic complex was constructed in two E-W rows above a relatively high basement of Tertiary sedimentary rocks and granodiorites west of Fukushima city. Volcanic activity has migrated to the east, with the Higashi-Azuma volcano group being the youngest. The symmetrical Azuma-Kofuji crater and a nearby fumarolic area on the flank of Issaikyo volcano are popular tourist destinations. The Azumayama complex contains several crater lakes, including Goshikinuma and Okenuma. Historical eruptions, mostly small phreatic explosions, have been restricted to Issaikyo volcano at the northern end of the Higashiyama group. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m Based on satellite and wind model data, and notices from PVMBG, the Darwin VAAC reported that during 12-16 and 18 June ash plumes from Dukono rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted in multiple directions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2 km exclusion zone. 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. Sources: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml; Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Ebeko | Paramushir Island (Russia) | 50.686°N, 156.014°E | Summit elev. 1103 m KVERT reported that a thermal anomaly over Ebeko was identified in satellite images on 12 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Geologic Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php Fuego | Guatemala | 14.473°N, 90.88°W | Summit elev. 3763 m INSIVUMEH reported that there were 10-20 explosions per hour recorded at Fuego during 15-18 June, generating ash plumes that rose as high as 1.1 km above the crater rim and drifted 10-25 km W, SW, and E. Explosions sometimes produced shock waves that rattled houses in nearby communities. Incandescent material was ejected 200-400 m high and caused avalanches of material that occasionally traveled long distances (reaching vegetated areas) down Seca (W), Taniluyá (SW), Ceniza (SSW), Trinidad (S), El Jute (SE), Las Lajas (SE), and Honda ravines. Ashfall was reported in several areas downwind including Santa SofÃa (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), Sangre de Cristo (8 km WSW), and El Porvenir (8 km ENE). 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/ Karymsky | Eastern Kamchatka (Russia) | 54.049°N, 159.443°E | Summit elev. 1513 m KVERT reported that a weak thermal anomaly at Karymsky was identified in satellite images during 8-14 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m KVERT reported that a weak thermal anomaly at Klyuchevskoy was visible in satellite images during 11-13 June. Explosions during 11-12 June were recorded in video and satellite data generating ash plumes that rose to 5.5-6 km (18,000-19,700 ft) a.s.l. and drifted 200 km WNW. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). 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 Krakatau | Indonesia | 6.102°S, 105.423°E | Summit elev. 813 m PVMBG reported that Anak Krakatauâ??s seismic network recorded one eruptive event at 0719 on 12 June. The event was not followed by visible ash emissions, though observations were hindered by weather conditions. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2 km radius hazard zone from the crater. Geologic Summary. The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 or 535 CE, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan, and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan, and left only a remnant of Rakata. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Kuchinoerabujima | Ryukyu Islands (Japan) | 30.443°N, 130.217°E | Summit elev. 657 m JMA reported that Kuchinoerabujimaâ??s Shindake Crater has not erupted since 3 February, and the number of shallow earthquakes located near the crater had been decreasing since then. Deeper volcanic earthquakes had not been recorded since 16 May. Sulfur dioxide emissions remained elevated. JMA lowered the Alert Level to 2 (the second lowest level on a scale of 1-5) on 12 June. Geologic Summary. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km west of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shintake, 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/ Manam | Papua New Guinea | 4.08°S, 145.037°E | Summit elev. 1807 m The Darwin VAAC reported that on 18 June ash plumes from Manam rose to altitudes of 3-3.7 km (14,000 ft) a.s.l. and drifted E and NE, based on satellite data and weather models. A thermal anomaly was also visible. Geologic Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml Pacaya | Guatemala | 14.382°N, 90.601°W | Summit elev. 2569 m INSIVUMEH reported that during 15-18 June Strombolian explosions at Pacayaâ??s Mackenney Crater ejected material as high as 30 m above the crater rim. A lava flow divided into two branches and traveled 300 m down the NW and W flanks, advancing towards Cerro Chino. Minor avalanches of material from lava flow fronts descended the flanks. 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/ Poas | Costa Rica | 10.2°N, 84.233°W | Summit elev. 2708 m OVSICORI-UNA reported that on 12 June small geyser-like eruptions at Poás ejected material less than 50 m high at a rate of about once per hour. At 0604 on 18 June an eruption that lasted about six minutes produced a plume of unknown height due to weather conditions. Residents reportedly heard several loud noises during 0610-0615 and observed an eruption plume rising from the crater. Ash fell in Cajón (12 km SW), San Luis de Grecia (11 km SW), Los Ã?ngeles, San Miguel, San Isidro (28 km SE), and San Roque (23 km SSE). Whitish ash deposits surrounding the crater, especially on the W and S sectors, were visible in webcam images. Geologic Summary. The broad, well-vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano, which is one of Costa Rica's most prominent natural landmarks, are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the 2708-m-high complex stratovolcano extends to the lower northern flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, is cold and clear and last erupted about 7500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since the first historical eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water. Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) http://www.ovsicori.una.ac.cr/ Santa Maria | Guatemala | 14.757°N, 91.552°W | Summit elev. 3745 m INSIVUMEH and CONRED reported that on 12 June lahars descended Santa MarÃa's Cabello de Ã?ngel (a tributary of Nima I) and San Isidro (tributary of El Tambor) drainages. The lahar in San Isidro was 15-17 m wide and 1.5 m deep, and carried shrubs, tree trunks, and blocks up to 2 m in diameter. On 16 June lahars again descended the San Isidro drainage. During 15-18 June explosions at Caliente cone generated ash plumes that rose 400-800 m and drifted SW and E. Avalanches of material descended the E and SE flanks of the cone, and during 17-18 June reached the base of the cone. Minor ashfall was reported in San Marcos (10 km SW), Loma Linda (6 km WSW), and Palajunoj (18 km SSW) during 17-18 June. Geologic Summary. Symmetrical, forest-covered Santa MarÃa volcano is one of the most prominent 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 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. 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/ Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m KVERT reported that a thermal anomaly at Sheveluchâ??s lava dome was identified in daily satellite images during 8-14 June. Explosions and hot avalanches of material were captured by video and satellite data during 11-12 June. Ash plumes from the events drifted 60 km WNW. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 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 Villarrica | Chile | 39.42°S, 71.93°W | Summit elev. 2847 m OVDAS-SERNAGEOMIN and ONEMI reported that during 1-31 May gas plumes rose as high as 170 m above Villarricaâ??s crater rim. Incandescence from the crater was periodically visible. POVI reported that on 17 June lava spattering above the crater rim was recorded by a newly-installed infrared webcam. Geologic Summary. Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km-wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot the flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano were produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 km2 of the volcano, and lahars have damaged towns on its flanks. Sources: Servicio Nacional de GeologÃa y MinerÃa (SERNAGEOMIN) http://www.sernageomin.cl/; Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI) http://www.onemi.cl/; Proyecto Observación Villarrica Internet (POVI) http://www.povi.cl/ ============================================================== 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. 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