Sally Kuhn Sennert - Weekly Report Editor (kuhns@xxxxxx)
URL: http://www.volcano.si.
New Activity/Unrest: Sinabung, Indonesia
Ongoing Activity: Colima, Mexico | Dukono, Halmahera (Indonesia) | Fuego, Guatemala | Katla, Iceland | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Nevado del Ruiz, Colombia | Nevados de Chillán, Chile | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Suwanosejima, Ryukyu Islands (Japan)
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
Sinabung | Indonesia | 3.17°N, 98.392°E | Summit elev. 2460 m
Based on satellite images, model data, and ground reports from PVMBG, the Darwin VAAC reported that during 1-3 September ash plumes from Sinabung rose to altitudes of 4.3-5.5 km (14,000-18,000 ft) a.s.l. and drifted W and WSW.
Geologic Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical, 2460-m-high andesitic-to-dacitic volcano is at the southern end of the four overlapping summit craters. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Ongoing Activity
Colima | Mexico | 19.514°N, 103.62°W | Summit elev. 3850 m
Based on satellite and webcam images, the Washington VAAC reported that on 1 September an ash plume from Colima rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted almost 30 km W.
Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4320 m high point of the complex) on the north and the 3850-m-high historically active Volcán de Colima at the south. A group of cinder cones of late-Pleistocene age is located on the floor of the Colima graben west and east of the Colima complex. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the south, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.
Source: Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.
Dukono | Halmahera (Indonesia) | 1.693°N, 127.894°E | Summit elev. 1229 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 31 August-6 September ash plumes from Dukono rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted as far as 230 km in multiple directions.
Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. This complex volcano presents a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of the summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.
Source: Darwin Volcanic Ash Advisory Centre (VAAC) ftp://ftp.bom.gov.au/
Fuego | Guatemala | 14.473°N, 90.88°W | Summit elev. 3763 m
INSIVUMEH reported that during 4-5 September incandescent material rose as high as 200 m above Fuego’s crater rim, and ash plumes rose 450 m and drifted W and SW. Sounds resembling train engines were constant and rumblings were heard six to nine times per hour. A 500-m-long lava flow was active in the Las Lajas (SE) drainage. Activity increased during the early afternoon on 5 September. The magnitude and number of explosion (6 per hour) increased, generating ash plumes that rose 850 m and drifted 12 km W and SW. The lava flow had grown to 1.2 km long. The rate of six explosion per hour continued on 6 September. Ash plumes rose 850 m and drifted 10 km W and SW, causing ashfall in Sangre de Cristo (8 km WSW), Panimache (8 km SW), and other nearby areas.
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.
Katla | Iceland | 63.633°N, 19.083°W | Summit elev. 1490 m
The Iceland Met Office (IMO) reported that seismic activity within Katla's caldera had increased in mid-June and then began to decline. On 29 August two earthquakes of about M 4.5 occurred in the NE part of the caldera, the largest earthquakes detected at Katla since 1977. The ensuing swarm that same day produced over 100 earthquakes, the largest of which was M 3.3. Seismicity was low after the swarm had ended.
Throughout the summer, electrical conductivity levels in the Múlakvísl River, which drains from the E side of the Mýrdalsjökull glacier that covers Katla, had remained unusually high, reflecting a constant source of geothermal meltwater. There had also been frequent reports of a sulfur odor close to Múlakvísl; gas measurements near the source of Múlakvísl revealed unhealthy levels of hydrogen sulfide, also indicating high concentrations of geothermal fluids. IMO noted that the recent earthquake activity does not appear to have significantly affected conductivity levels in Múlakvísl.
IMO stated that summertime increases in caldera seismicity are an almost annual occurrence at Katla, often associated with the drainage of geothermal meltwater causing minor floods in glacial rivers from Mýrdalsjökull.
Geologic Summary. Katla volcano, located near the southern end of Iceland's eastern volcanic zone, is hidden beneath the Myrdalsjökull icecap. The subglacial basaltic-to-rhyolitic volcano is one of Iceland's most active and is a frequent producer of damaging jökulhlaups, or glacier-outburst floods. A large 10 x 14 km subglacial caldera with a long axis in a NW-SE direction is up to 750 m deep. Its high point reaches 1380 m, and three major outlet glaciers have breached its rim. Although most historical eruptions have taken place from fissures inside the caldera, the Eldgjá fissure system, which extends about 60 km to the NE from the current ice margin towards Grímsvötn volcano, has been the source of major Holocene eruptions. An eruption from the Eldgjá fissure system about 934 CE produced a voluminous lava flow of about 18 cu km, one of the world's largest known Holocene lava flows. Katla has been the source of frequent subglacial basaltic explosive eruptions that have been among the largest tephra-producers in Iceland during historical time and has also produced numerous dacitic explosive eruptions during the Holocene.
Source: Icelandic Met Office http://en.vedur.is/
Kilauea | Hawaiian Islands (USA) | 19.421°N, 155.287°W | Summit elev. 1222 m
During 31 August-6 September HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent. Incandescence was evident in webcam images from several long-established vents on Pu'u 'O'o Crater's floor. A collapse at the W vent increased the size of the vent and a 40-m-diameter lava pond that was 23 m below the vent's rim. The 61G lava flow, originating from a vent on Pu'u 'O'o Crater's E flank, continued to enter the ocean at multiple areas near Kamokuna and spanning about 1 km of coastline and increasing the size of the lava delta at the base of the sea cliff. Scattered breakouts were active on the coastal plain and the pali.
Geologic Summary. Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/
Klyuchevskoy | Central Kamchatka (Russia) | 56.056°N, 160.642°E | Summit elev. 4754 m
KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 26 August-2 September. Volcanic bombs that were ejected above the summit crater and the cinder cone landed in the Apakhonchich drainage on the SE flank. A lava flow traveled down the Apakhonchich drainage and also down the SW flank. Satellite images showed a large and bright daily thermal anomaly at the volcano, and ash plumes drifting 230 km NE, SE, S, and SW. The Aviation Color Code remained at Orange.
Geologic Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Nevado del Ruiz | Colombia | 4.892°N, 75.324°W | Summit elev. 5279 m
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 23-29 August seismicity at Nevado del Ruiz was relatively unchanged compared to the previous week. Significant amounts of water vapor and gas rose from the crater. Ash emissions occurred on several days, and sometimes several times per day. Based on notices from the Bogota MWO, satellite and webcam images, and model data, the Washington VAAC reported that during 2-3 September ash plumes rose to altitudes of 6.1-6.4 km (20,000-21,000 ft) a.s.l. and drifted W and NW. SGC noted that gas, steam, and ash plumes occasionally rose 1.8 km above the crater rim and drifted NW and W on 4 and 6 September. The Alert Level remained at III (Yellow; the second lowest level on a four-color scale).
Geologic Summary. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers >200 sq km. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.
Sources: Servicio Geológico Colombiano (SGC) http://www.ingeominas.
Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.
Nevados de Chillán | Chile | 36.863°S, 71.377°W | Summit elev. 3212 m
The Buenos Aires VAAC reported that on 2 September steam-and-gas emissions from Nevados de Chillán possibly contained minor amounts of ash. On 6 September the webcam recorded a short-duration, intense ash emission.
Geologic Summary. The compound volcano of Nevados de Chillán is one of the most active of the Central Andes of Chile. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, 3212-m-high Cerro Blanco (Volcán Nevado), is located at the NW end of the group, and 3089-m-high Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in altitude. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986, eventually exceeding its height by 20 m.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.smn.gov.ar/
Santa Maria | Guatemala | 14.756°N, 91.552°W | Summit elev. 3772 m
INSIVUMEH reported that explosions at 0001, 0015, and 0018 on 4 September generated a mushroom-shaped ash plume that rose 2 km above Santa María's Santiaguito lava-dome complex and drifted SE and E. Pyroclastic flows traveled 2 km down the WSW, S, and SE flanks. Ash fell in Santa María de Jesús. On 5 September the seismic network recorded two moderate explosions. Gas emissions rose from the complex during 5-6 September.
Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.
Sheveluch | Central Kamchatka (Russia) | 56.653°N, 161.36°E | Summit elev. 3283 m
KVERT reported that during 26 August-2 September lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a daily thermal anomaly over the dome. The Aviation Color Code remained at Orange.
Geologic Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/
Suwanosejima | Ryukyu Islands (Japan) | 29.638°N, 129.714°E | Summit elev. 796 m
Based on a pilot observation and satellite data, the Tokyo VAAC reported that on 31 August ash plume from Suwanosejima rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted E.
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 of the volcano 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: Tokyo Volcanic Ash Advisory Center (VAAC) http://ds.data.jma.go.
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