Active volcanoes in the world: September 21 – 27, 2016

New activity/unrest was reported for 5 volcanoes between September 21 and 27, 2016. During the same period, ongoing activity was observed at 10 volcanoes.

New activity/unrest: Klyuchevskoy, Central Kamchatka (Russia) | Rinjani, Lombok Island (Indonesia) | Tengger Caldera, Eastern Java (Indonesia) | Tungurahua, Ecuador | Turrialba, Costa Rica.

Ongoing activity: Bagana, Bougainville (Papua New Guinea) | Colima, Mexico | Copahue, Central Chile-Argentina border | Dukono, Halmahera (Indonesia) | Fuego, Guatemala  | Kilauea, Hawaiian Islands (USA) | Nevado del Ruiz, Colombia | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia.

New activity/unrest

Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Summit elev. 4754 m

KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 16-23 September. Volcanic bombs that were ejected above the summit crater and the cinder cone landed in the Apakhonchich drainage on the E 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. During 20-22 September explosions generated ash plumes that rose as high as 7 km (23,000 ft) a.s.l. and drifted 100 km SW, E, and SE. The Aviation Color Code remained at Orange.

Geological 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.

Rinjani, Lombok Island (Indonesia)
8.42°S, 116.47°E, Summit elev. 3726 m

PVMBG reported that at 1445 on 27 September a small-scale explosive eruption at Rinjani's Barujari Crater produced an ash plume rose that rose 2 km above the crater and drifted WSW. The eruption was preceded by an increase in seismicity, but the number and amplitude of the events were insignificant. The Alert Level was raised to 2 (on a scale of 1-4), and the public was warned not to approach the crater within a 3-km radius.

Geological summary: Rinjani volcano on the island of Lombok rises to 3726 m, second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the west side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak (Samalas) caldera. The caldera formed during one of the largest Holocene eruptions globally in 1257 CE, which truncated Samalas stratovolcano. The western half of the caldera contains a 230-m-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the east end of the caldera. Historical eruptions dating back to 1847 have been restricted to Barujari cone and consist of moderate explosive activity and occasional lava flows that have entered Segara Anak lake.

Tengger Caldera, Eastern Java (Indonesia)
7.942°S, 112.95°E, Summit elev. 2329 m

PVMBG reported that during 1 June-25 September brownish gray plumes from Tengger Caldera's Bromo cone rose as high as 1.2 km above the crater. A sulfur odor was noted at the Bromo observation post, thunderous noises sometimes vibrated the post doors, and occasionally crater incandescence was observed. Seismic activity was dominated by shallow volcanic earthquakes and tremor. The deformation network measured inflation. Based on analyses of satellite images and information from PVMBG, the Darwin VAAC reported that during 22-23 September ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. (720 m above the crater) and drifted almost 40 km SW. On 26 September the Alert Level was raised to 3 (on a scale of 1-4); residents and visitors were reminded not to approach the crater within a radius of 2.5 km.

Geological summary: The 16-km-wide Tengger caldera is located at the northern end of a volcanic massif extending from Semeru volcano. The massive volcanic complex dates back to about 820,000 years ago and consists of five overlapping stratovolcanoes, each truncated by a caldera. Lava domes, pyroclastic cones, and a maar occupy the flanks of the massif. The Ngadisari caldera at the NE end of the complex formed about 150,000 years ago and is now drained through the Sapikerep valley. The most recent of the calderas is the 9 x 10 km wide Sandsea caldera at the SW end of the complex, which formed incrementally during the late Pleistocene and early Holocene. An overlapping cluster of post-caldera cones was constructed on the floor of the Sandsea caldera within the past several thousand years. The youngest of these is Bromo, one of Java's most active and most frequently visited volcanoes.

Tungurahua, Ecuador
1.467°S, 78.442°W, Summit elev. 5023 m

IG reported that Tungurahua's seismic network detected a significant increase in the number of long-period (LP) earthquakes on 12 September and small episodes of tremor beginning on 16 September. A swarm of 24 LP events were detected during 0408-0424 on 18 September. Starting at 1400 on 24 September the number of LP events again increased. Gas emissions were low, and together with the increased seismicity, possibly indicates a blocked conduit. IG noted that a possible large-scale eruption may happen within hours to days. In response, the Secretaría de Gestión de Riesgos (SGR) announced that the Alert Level was raised from Yellow to Orange (the second highest on a 4-color scale) on 26 September.

Geological summary: Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

Turrialba, Costa Rica
10.025°N, 83.767°W, Summit elev. 3340 m

OVSICORI-UNA reported that during 21-22 September multiple eruptive episodes at Turrialba generated ash, gas, and steam emissions that generally rose as high as 700 m above the crater and drifted N, NW, W, and SW. Ashfall and a sulfur odor were reported in some areas of Valle Central. An energetic episode that began at 0320 on 22 September produced an ash plume that rose 2 km and drifted WSW. Another episode accompanied by tremor which began at 1345 generated an ash plume that rose 1 km. Surficial activity significantly decreased on 23 September; a few short episodes were detected but weather clouds prevented observations. Seismicity remained high, characterized by very-long-period events. Seismicity decreased on 24 September and activity was very low through the afternoon of 25 September; a few minor eruptions were detected. At 2110 on 25 September an eruption was detected seismically, but cloud cover blocked views. Ashfall and a sulfur odor was reported in Valle Central communities, including San José and Heredia. An eruption at 1225 on 26 September produced an ash plume that rose 1 km and drifted NW. Cloud cover again prevented visual observations of activity that began at 1242, and lasted for four hours. Based on the amplitude of the seismic signal, webcam images, and observations from scientists in the field, ash plumes were estimated to rise as high as 2 km. Continuous passive emissions continued to rise as high as 2 km until 1000 on 27 September; between 1000 and 1242 ash plumes rose 300-500 m.

Geological summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Ongoing activity

Bagana, Bougainville (Papua New Guinea)
6.137°S, 155.196°E, Summit elev. 1855 m

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 27 September ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 85-95 km SW and WSW.

Geological summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is frequent and characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although explosive activity occasionally producing pyroclastic flows also occurs. Lava flows form dramatic, freshly preserved tongue-shaped lobes up to 50 m thick with prominent levees that descend the flanks on all sides.

Colima, Mexico

19.514°N, 103.62°W, Summit elev. 3850 m

Based on webcam and satellite images, and information from the Mexico City MWO, the Washington VAAC reported that on 25 September an ash emission from Colima rose to an altitude of 5.2 km (17,000 ft) a.s.l. and drifted NNE.

Geological 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.

Copahue, Central Chile-Argentina border
37.856°S, 71.183°W, Summit elev. 2953 m

The Buenos Aires VAAC reported that on 23 September the webcam at Copahue recorded steam-and-gas emissions possibly containing minor amounts of ash.

Geological 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 Río 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 at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.

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 21-27 September ash plumes from Dukono rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and, on some days, drifted as far as 160 km in multiple directions.

Geological 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.

Fuego, Guatemala
14.473°N, 90.88°W, Summit elev. 3763 m

INSIVUMEH reported that during 23-26 September lava fountains rose as high as 200 m above Fuego’s crater rim, and lava flows traveled 3.5 km SE in the Las Lajas drainage. Explosions occurring at a rate of 3-4 per hour produced ash plumes that rose 450-850 m and drifted 8-12 km E, S, SW, and W. On 26 September a 10-m-wide and 1-m-deep lahar, triggered by heavy rain in the area, descended the Santa Teresa (W) drainage, a tributary of the Pantaleón river. The lahar carried blocks 50 cm in diameter, branches, and tree trunks. Moderate to large explosions generated ash plumes that rose 1.2 km and drifted 20 km W and SW. Lava fountains rose 200-300 m and fed two lava flows; the first traveled 1.5 km down the Las Lajas drainage and the second traveled 1.8 km down the Santa Teresa drainage. Avalanches originated from a degassing fissure on the S flank. Ashfall was reported in areas on the W and SW flank, including the Palo Verde finca, Sangre de Cristo (8 km WSW), and Yepocapa (8 km NW).

Geological 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.

Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m

During 21-27 September HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent. The lake level rose as high as 10 m below the Halema?uma?u floor, and was sometimes visible from the Jaggar Museum (NW rim of Kilauea Caldera); lava fountains along the edge of the lake were visible from the museum on 26 September. Webcams recorded incandescence from long-active sources within Pu'u 'O'o Crater. 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. Scattered breakouts were active 2 km inland from the coast.

Geological 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.

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 20-26 September seismicity at Nevado del Ruiz was characterized by an increased number of earthquakes and a slight decrease in the seismic energy compared to the previous week. Significant amounts of water vapor and gas rose from the crater. Gas, steam, and ash plumes rose 700 m above the crater on 21 September and drifted NW. The Alert Level remained at III (Yellow; the second lowest level on a four-color scale).

Geological 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.

Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m

INSIVUMEH reported that a strong explosion at 0345 on 25 September generated an ash plume that rose 2 km above Santa María's Santiaguito lava-dome complex and drifted W and SW. An explosion the next morning generated an ash plume that rose 1 km and drifted 15 km SW. A moderate explosion was detected by the seismic network at 0436 on 27 September; inclement weather prevented visual observations of the crater.

Geological 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.

Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m

KVERT reported that during 16-23 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. A moderate explosion on 18 September caused dome collapse and 10-km-long pyroclastic flows. Pyroclastic-flow deposits were noted in the Baydarnaya River valley and in the central part of the S flank. The Aviation Color Code remained at Orange.

Geological 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.

Sinabung, Indonesia
3.17°N, 98.392°E, Summit elev. 2460 m

Based on satellite images, the Jakarta MWO, and ground reports from PVMBG, the Darwin VAAC reported that during 23-25 September ash plumes from Sinabung rose to altitudes of 3.6-4.2 km (12,000-14,000 ft) a.s.l. and drifted E, ESE, and SE.

Geological 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: GVP