4-4-4-4-4-4-4-4-4-4-4-4-4 From: "Kuhn, Sally" <KUHNS@xxxxxx> Smithsonian / USGS Weekly Volcanic Activity Report 15-21 July 2020 Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx) URL: https://volcano.si.edu/reports_weekly.cfm New Activity/Unrest: Makushin, Fox Islands (USA) | Nishinoshima, Japan | Pacaya, Guatemala | Raung, Eastern Java (Indonesia) | Telica, Nicaragua | Turrialba, Costa Rica Ongoing Activity: Agung, Bali (Indonesia) | Copahue, Central Chile-Argentina border | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Ibu, Halmahera (Indonesia) | Kadovar, Papua New Guinea | Karymsky, Eastern Kamchatka (Russia) | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Stromboli, Aeolian Islands (Italy) | Suwanosejima, Ryukyu Islands (Japan) | Yasur, Vanuatu 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 Makushin | Fox Islands (USA) | 53.891°N, 166.923°W | Summit elev. 1800 m AVO reported that small earthquakes in an area about 10 km E of the Makushinâ??s summit and at a depth of about 8 km continued to be detected during 15-21 July. Since the onset of seismicity on 15 June, the earthquakes had generally decreased in both size and rate. No surficial activity was visible in satellite or webcam images; only typical minor steaming from the summit crater lake. Weakly elevated surface temperatures were identified in satellite data during 20-21 July. The Aviation Color Code and Volcano Alert Level remained at Yellow and Advisory, respectively. Geologic Summary. The ice-covered, 1800-m-high Makushin volcano on northern Unalaska Island west of the town of Dutch Harbor is capped by a 2.5-km-wide caldera. The broad, domical structure of Makushin contrasts with the steep-sided profiles of most other Aleutian stratovolcanoes. Much of the volcano was formed during the Pleistocene, but the caldera (which formed about 8000 years ago), Sugarloaf cone on the ENE flank, and a cluster of about a dozen explosion pits and cinder cones at Point Kadin on the WNW flank, are of Holocene age. A broad band of NE-SW-trending satellitic vents cuts across the volcano. The composite Pakushin cone, with multiple summit craters, lies 8 km to the SW of Makushin. Frequent explosive eruptions have occurred during the past 4000 years, sometimes accompanied by pyroclastic flows and surges. Geothermal areas are found in the summit caldera of Makushin and on the SE and eastern flanks of the volcano. They represent the largest and most investigated high-temperature geothermal resources in Alaska. Small-to-moderate explosive eruptions have been recorded at Makushin since 1786. Source: US Geological Survey Alaska Volcano Observatory (AVO) https://avo.alaska.edu/ Nishinoshima | Japan | 27.247°N, 140.874°E | Summit elev. 25 m JMA scientists observed Nishinoshima from a ship on 11 July. They reported that a large amount of ash was emitted from the summit crater; plumes rose about 1.7 km and drifted W, dropping ash into the sea. Deposits of large blocks at the foot of the cone were visible. Lava fountains that rose 200 m above the crater were observable at night, along with lightning in the ash plumes. The cone had grown to about 200 m, about 40 m higher than an estimate on 1 December 2019. The report stated that ships should stay at least 2.5 km away from the cone. Based on satellite data and pilot observations, the Tokyo VAAC reported that during 16-21 July ash plumes rose to 3.7-6.4 km (12,000-21,000 ft) a.s.l. and drifted N, NE, and E. Satellite data showed a sulfur dioxide plume reaching the western USA on 18 July, after traveling over 9,000 km from Nishinoshima. Geologic Summary. The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE. Sources: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/; Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.jp/svd/vaac/data/vaac_list.html; Simon Carn http://www.volcarno.com/ Pacaya | Guatemala | 14.382°N, 90.601°W | Summit elev. 2569 m INSIVUMEH reported that during 15-21 July Strombolian explosions at Pacayaâ??s Mackenney Crater ejected material as high as 100 m above the crater rim. Lava-flow effusion ceased during 14-19 July, though flows may have continued to advance or be active on the SW, NW, N, and NE flanks. On 20 July lava emerged from a fissure or vents at the NW base of the cone, near Cerro Chino, and traveled SE. 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/ Raung | Eastern Java (Indonesia) | 8.119°S, 114.056°E | Summit elev. 3260 m PVMBG reported that during 1 January-15 July white plumes at Raung rose as high as 50 m above the summit. Seismicity increased on 13 July and then again on 16 July. At 1052 on 16 July observers noted that the color of the emissions had become brownish white and rose higher. A VONA stated that at 1353 an ash plume rose 100 m above the summit and drifted N. At 1356 the color of the emissions changed to white and gray, and plumes rose to 100 m above the summit. During the rest of the day gray and reddish-colored plumes rose 50-200 m. There were 60 emissions recorded in total. During 0000-0600 on 17 July there were a total of 26 emissions characterized by brownish ash plumes rising 50-200 m. PVMBG raised the Alert Level to 2 (on a scale of 1-4), and the public was reminded not to approach the crater within a 2-km radius. Geologic Summary. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and W, respectively. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Telica | Nicaragua | 12.606°N, 86.84°W | Summit elev. 1036 m SINAPRED stated that at 1659 on 20 July small explosions at Telica produced a gas-and-ash plume that rose 200 m above the crater rim as reported by INETER. RSAM values increased from 57 to 153 units at the time of the explosions, and remained elevated at 144 units afterwards. SINAPRED recommended that the public stay at least 1.5 km away from the crater. Geologic Summary. Telica, one of Nicaragua's most active volcanoes, has erupted frequently since the beginning of the Spanish era. This volcano group consists of several interlocking cones and vents with a general NW alignment. Sixteenth-century eruptions were reported at symmetrical Santa Clara volcano at the SW end of the group. However, its eroded and breached crater has been covered by forests throughout historical time, and these eruptions may have originated from Telica, whose upper slopes in contrast are unvegetated. The steep-sided cone of Telica is truncated by a 700-m-wide double crater; the southern crater, the source of recent eruptions, is 120 m deep. El Liston, immediately E, has several nested craters. The fumaroles and boiling mudpots of Hervideros de San Jacinto, SE of Telica, form a prominent geothermal area frequented by tourists, and geothermal exploration has occurred nearby. Source: Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED) http://www.sinapred.gob.ni/ Turrialba | Costa Rica | 10.025°N, 83.767°W | Summit elev. 3340 m OVSICORI-UNA reported that ash emissions of variable densities were visible at Turrialba almost daily during 16-20 July. Ash plumes rose as high as 200 m above the crater rim each day during 16-18 July. 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 edifice covers an area of 500 km2. 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/ Ongoing Activity Agung | Bali (Indonesia) | 8.343°S, 115.508°E | Summit elev. 2997 m PVMBG reported that the last eruption at Agung was recorded at 0138 on 13 June 2019. Over the past year seismicity had generally decreased; volcanic earthquakes continued to be recorded but at a low occurrence rate. Deformation data indicated a deflationary pattern which had stabilized in recent months. A thermal anomaly was last visible in satellite data in October 2019 and did not reappear. White plumes were visible rising 20-150 m above the summit during 1 January-16 July. PVMBG lowered the Alert Level at Agung to 2 (on a scale of 1-4) on 16 July, stating that the public should not enter an exclusion zone set at a 2-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/ Copahue | Central Chile-Argentina border | 37.856°S, 71.183°W | Summit elev. 2953 m SERNAGEOMIN reported that an ash plume from Copahue was visible on 16 July. The Alert Level remained at Green (the lowest level on a four-color scale) and the public was reminded to stay 500 m away from El Agrio crater. Geologic Summary. Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the RÃo Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments. Source: Servicio Nacional de GeologÃa y MinerÃa (SERNAGEOMIN) http://www.sernageomin.cl/ Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m Based on information from PVMBG and satellite data the Darwin VAAC reported that ash plumes from Dukono rose to 2.1-2.3 km (7,000-8,000 ft) a.s.l. and drifted NW and W during 15-21 July. The Alert Level remained at a 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: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/; Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml Ebeko | Paramushir Island (Russia) | 50.686°N, 156.014°E | Summit elev. 1103 m Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 15-16 July that sent ash plumes up to 3.6 km (11,800 ft) a.s.l. Ash plumes drifted SE, causing ashfall in Severo-Kurilsk on 15 July. A thermal anomaly over the volcano was identified in satellite images on those same days. 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 Ibu | Halmahera (Indonesia) | 1.488°N, 127.63°E | Summit elev. 1325 m PVMBG reported that during 15-20 July white and gray plumes with variable densities rose 200-800 m above Ibuâ??s summit and drifted in multiple directions; weather conditions prevented visual observations on 17 July. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side. Geologic Summary. The truncated summit of Gunung Ibu stratovolcano along the NW coast of Halmahera Island has large nested summit craters. The inner crater, 1 km wide and 400 m deep, contained several small crater lakes through much of historical time. The outer crater, 1.2 km wide, is breached on the north side, creating a steep-walled valley. A large parasitic cone is located ENE of the summit. A smaller one to the WSW has fed a lava flow down the W flank. A group of maars is located below the N and W flanks. Only a few eruptions have been recorded in historical time, the first a small explosive eruption from the summit crater in 1911. An eruption producing a lava dome that eventually covered much of the floor of the inner summit crater began in December 1998. Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/; Darwin Volcanic Ash Advisory Centre (VAAC) http://www.bom.gov.au/aviation/volcanic-ash/darwin-va-advisory.shtml Kadovar | Papua New Guinea | 3.608°S, 144.588°E | Summit elev. 365 m RVO reported minor eruptive activity at Kadovar during 1-15 July consisting of occasional light gray ash plumes of variable densities rising a few hundred meters above the summit crater. Fluctuating summit incandescence was visible at night. Activity intensified on 5 July as emissions became dark gray and dense. Explosions at 1652 and 1815 generated dense dark gray ash plumes that rose 1 km and drifted W. Loud rumbling accompanied the explosion. Activity subsided later that day but was again more intense during 8-10 July. Explosions recorded at 2045 on 8 July, 1145 and 1400 on 9 July, and at 0950 and 1125 on 10 July produced ash plumes that rose 1 km above the summit. Geologic Summary. The 2-km-wide island of Kadovar is the emergent summit of a Bismarck Sea stratovolcano of Holocene age. It is part of the Schouten Islands, and lies off the coast of New Guinea, about 25 km N of the mouth of the Sepik River. Prior to an eruption that began in 2018, a lava dome formed the high point of the andesitic volcano, filling an arcuate landslide scarp open to the south; submarine debris-avalanche deposits occur in that direction. Thick lava flows with columnar jointing forms low cliffs along the coast. The youthful island lacks fringing or offshore reefs. A period of heightened thermal phenomena took place in 1976. An eruption began in January 2018 that included lava effusion from vents at the summit and at the E coast. Source: Rabaul Volcano Observatory (RVO) Karymsky | Eastern Kamchatka (Russia) | 54.049°N, 159.443°E | Summit elev. 1513 m KVERT reported that a thermal anomaly over Karymsky was identified in satellite images on 13 and 15 July. A gas-and-steam plume containing some ash drifted 26 km SW on 14 July. 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 Semeru | Eastern Java (Indonesia) | 8.108°S, 112.922°E | Summit elev. 3657 m PVMBG reported that ash plumes from Semeru rose 500 m above the summit and drifted N during 16-17 July. Weather conditions prevented visual observations during 15 and 18-21 July. The Alert Level remained at 2 (on a scale of 1-4), and the public was reminded to stay outside of the general 1-km radius from the summit and 4 km on the SSE flank. Geologic Summary. Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM) http://vsi.esdm.go.id/ Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 10-17 July. 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 Stromboli | Aeolian Islands (Italy) | 38.789°N, 15.213°E | Summit elev. 924 m INGV reported that during 13-19 July activity at Stromboli was characterized by ongoing explosive activity from two vents in Area N (north crater area) and four vents in Area C-S (south-central crater area). Explosions at the N1 vent in Area N sometimes ejected tephra 200 m high, and ejected lapilli and bombs radially. Low-intensity explosions at vent N2 ejected tephra 80 m high. Explosions at the S1 and S2 vents in Area C-S ejected tephra. A vent between S2 and C (Area C-S) was noted on 18 July and produced occasional explosions. A sequence of high-energy explosions began at 0500 on 19 July and ended at 0504. The first explosion originated at the central vent in Area C-S but within a few seconds involved all Area C-S vents. An ash plume rose as high as 1 km. Tephra was ejected radially; some material was deposited along the Sciara del Fuoco and reached the coast within about 40 seconds after the beginning of the event. Tephra fell in the towns of Liscione and Roccette. The event damaged the infrared camera at Pizzo (400 m elevation). Geologic Summary. Spectacular incandescent nighttime explosions at this volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small island is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded for more than a millennium. Source: Sezione di Catania - Osservatorio Etneo (INGV) http://www.ct.ingv.it/ Suwanosejima | Ryukyu Islands (Japan) | 29.638°N, 129.714°E | Summit elev. 796 m JMA reported that nighttime incandescence at Suwanosejimaâ??s Ontake Crater was occasionally visible during 10-17 July. Occasional eruptive events were recorded along with three explosions. One of them, recorded at 1630 on 12 July, generated a gray-white plume that rose as high as 1.5 km above the crater rim and entered a weather cloud. An explosion at 2006 on 15 July ejected large rocks as far as 300 m from the crater. The Alert Level remained at 2 (on a 5-level scale). Geologic Summary. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island. Source: Japan Meteorological Agency (JMA) http://www.jma.go.jp/jma/ Yasur | Vanuatu | 19.532°S, 169.447°E | Summit elev. 361 m Based on webcam images and satellite data the Wellington VAAC reported that on 19 July ash plumes from Yasur rose to 1.5 km (5,000 ft) a.s.l. Diffuse ash plumes rose to 1.2 km (4,000 ft) a.s.l. and drifted NNE. 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. Located at the SE tip of Tanna Island, this mostly unvegetated pyroclastic cone has a nearly circular, 400-m-wide summit crater. The active cone is largely contained within the small Yenkahe caldera, and is the youngest of a group of Holocene volcanic centers constructed over the down-dropped NE flank of the Pleistocene Tukosmeru volcano. The Yenkahe horst is located within the Siwi ring fracture, a 4-km-wide, horseshoe-shaped caldera associated with eruption of the andesitic Siwi pyroclastic sequence. Active tectonism along the Yenkahe horst accompanying eruptions has raised Port Resolution harbor more than 20 m during the past century. Source: Wellington Volcanic Ash Advisory Center (VAAC) http://vaac.metservice.com/ 4-4-4-4-4-4-4-4-4-4-4-4-4 ============================================================== 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 - https://www.iavceivolcano.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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