New activity/unrest was observed at 3 volcanoes between August 24 and 30, 2016. During the same period, ongoing activity was observed at 13 volcanoes.
New activity/unrest: Chikurachki, Paramushir Island (Russia) | Santa Maria, Guatemala | Sinabung, Indonesia.
Ongoing activity: Bagana, Bougainville (Papua New Guinea) | Colima, Mexico | Cotopaxi, Ecuador | Dukono, Halmahera (Indonesia) | Ibu, Halmahera (Indonesia) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Masaya, Nicaragua | Nevado del Ruiz, Colombia | Nishinoshima, Japan | Sheveluch, Central Kamchatka (Russia) | Stromboli, Aeolian Islands (Italy) | Suwanosejima, Ryukyu Islands (Japan).
Chikurachki, Paramushir Island (Russia)
50.324°N, 155.461°E, Summit elev. 1781 m
Based on satellite observations, KVERT reported that on 30 August a gas-and-ash plume from Chikurachki rose to an altitude of 2.5 km (8,200 ft) a.s.l. and drifted 35 km SE. The Aviation Color Code was raised to Yellow (the second lowest level on a four-color scale).
Geological summary: Chikurachki, the highest volcano on Paramushir Island in the northern Kuriles, is actually a relatively small cone constructed on a high Pleistocene volcanic edifice. Oxidized basaltic-to-andesitic scoria deposits covering the upper part of the young cone give it a distinctive red color. Frequent basaltic plinian eruptions have occurred during the Holocene. Lava flows from 1781-m-high Chikurachki reached the sea and form capes on the NW coast; several young lava flows also emerge from beneath the scoria blanket on the eastern flank. The Tatarinov group of six volcanic centers is located immediately to the south of Chikurachki, and the Lomonosov cinder cone group, the source of an early Holocene lava flow that reached the saddle between it and Fuss Peak to the west, lies at the southern end of the N-S-trending Chikurachki-Tatarinov complex. In contrast to the frequently active Chikurachki, the Tatarinov volcanoes are extensively modified by erosion and have a more complex structure. Tephrochronology gives evidence of only one eruption in historical time from Tatarinov, although its southern cone contains a sulfur-encrusted crater with fumaroles that were active along the margin of a crater lake until 1959.
Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m
INSIVUMEH reported that at 0858 on 28 August a strong Vulcanian explosion at Santa María’s Santiaguito lava-dome complex generated a dense ash plume that rose 2.5 km and drifted 100 km W and SW. Pyroclastic flows descended the flanks. Ashfall was reported in San Marcos (10 km SW), Loma Linda (6 km WSW), and Palajunoj (18 km SSW), and was expected to impact additional areas downwind as the plume continued to drift. Moderate explosions were detected later that day. On 29 August a 25-m-wide, 1.5-m-deep hot lahar triggered by rainfall descended the Cabello de Ángel drainage, a tributary of the Nimá I river drainage on the S flank, carrying tree trunks and blocks up to 1.5 m in diameter. The lahar had a strong sulfur odor. White-and-blue gas emissions were observed on 30 August.
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.
3.17°N, 98.392°E, Summit elev. 2460 m
BNPB reported increased activity at Sinabung on 24 August. Observers at the PVMBG Sinabung observation post noted a marked increase in seismicity, and counted 19 pyroclastic flows and 137 avalanches from the early morning until the late afternoon. Foggy conditions obscured visual observations of the activity through most of the day, although incandescent lava as far as 500 m SSE and 1 km ESE was noted in the morning, and a pyroclastic flow was seen traveling 3.5 km ESE at 1546. The lava dome had grown to a volume of 2.6 million cubic meters. There continued to be 2,592 families (9,319 people) displaced to nine shelters. Activity remained very high on 25 August; pyroclastic flows continuously descended the flanks, traveling as far as 2.5 km E and SE, and 84 avalanches occurred during the first part of the day. Based on satellite images and model data, the Darwin VAAC reported that on 26 August ash plumes rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted NW and NNE. On 29 August ash plumes reported by ground-based observers rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted ENE. The next day an ash plume rose to an altitude of 5.2 km (17,000 ft) a.s.l. and drifted NW. The Alert Level remained at 4 (on a scale of 1-4), with an exclusion zone of 7 km from the volcano on the SSE sector, and 6 km in the ESE sector, and 4 km in the NNE sector.
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.
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 during 29-30 August ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W and WNW.
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, roughly 1850-m-high 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 volcano's flanks on all sides. Satellite thermal measurements indicate a continuous eruption from before February 2000 through at least late August 2014.
19.514°N, 103.62°W, Summit elev. 3850 m
Based on satellite and webcam images, and information from the Mexico City MWO, the Washington VAAC reported that during 26-27 August ash plumes from Colima rose to altitudes of 5.2-5.8 km (17,000-19,000 ft) a.s.l. and drifted SE and S. Plumes drifted almost 30 km on 27 August. The webcam recorded an ash plume rising to an altitude of 6.1 km (20,000 ft) a.s.l. on 29 August.
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.
0.677°S, 78.436°W, Summit elev. 5911 m
IG reported that during 1 January-24 August seismicity at Cotopaxi remained low. Small, intermittent gas emissions mostly stayed near the crater rim and on rare occasions rose no higher than 500 m above the rim. Emissions drifted down the W flank and remobilized ash deposits which were sometimes reported by Parque Nacional Cotopaxi visitors.
Geological summary: Symmetrical, glacier-clad Cotopaxi stratovolcano is Ecuador's most well-known volcano and one of its most active. The steep-sided cone is capped by nested summit craters, the largest of which is about 550 x 800 m in diameter. Deep valleys scoured by lahars radiate from the summit of the andesitic volcano, and large andesitic lava flows extend to its base. The modern conical edifice has been constructed since a major collapse sometime prior to about 5000 years ago. Pyroclastic flows (often confused in historical accounts with lava flows) have accompanied many explosive eruptions, and lahars have frequently devastated adjacent valleys. The most violent historical eruptions took place in 1744, 1768, and 1877. Pyroclastic flows descended all sides of the volcano in 1877, and lahars traveled more than 100 km into the Pacific Ocean and western Amazon basin. The last significant eruption took place in 1904.
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 24-30 August 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 280 km W, NW, N NE, and E.
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.
Ibu, Halmahera (Indonesia)
1.488°N, 127.63°E, Summit elev. 1325 m
PVMBG reported that during 1 June-22 August white-to-medium-gray plumes rose as high as 800 m above Ibu’s summit crater and drifted E, although inclement weather often prevented visual observations. Seismicity was dominated by signals indicating surface or near-surface activity, and the continued growth of the lava dome in the N part of the crater. The Alert Level remained at 2 (on a scale of 1-4). The public was warned to stay at least 2 km away from the active crater, and 3.5 km away on the N side.
Geological 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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m
During 24-30 August HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent. Several incandescent vents on Pu’u ‘O’o Crater’s floor were evident in webcam images. 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.
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.
Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Summit elev. 4754 m
KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 19-26 August. 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. Satellite images showed a large and bright daily thermal anomaly at the volcano. 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.
11.984°N, 86.161°W, Summit elev. 635 m
Based on analysis of satellite imagery, the Washington VAAC reported that on 28 August a gas plume with possible ash rose from Masaya to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted over 45 km W.
Geological summary: Masaya is one of Nicaragua''s most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano''s molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.
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 slightly increased compared to the week before. Significant amounts of water vapor and gas rose from the crater. Thermal anomalies were detected on 24 and 29 August. A period of tremor that started at 1747 on 26 August was associated with an ash emission that rose 900 m above the crater. A gas-and-ash plume, associated with a seismic signal at 1050 on 27 August, was confirmed by a pilot. Based on webcam images and seismic signals, an ash plume rose 1.3 km and drifted NW on 28 August. Gas, steam, and ash plumes occasionally rose 2.3 km above the crater rim and drifted NW and W on 29 August. 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.
27.247°N, 140.874°E, Summit elev. 25 m
JMA reported that no additional activity was observed after the 17 November 2015 eruption at Nishinoshima, which ejected bombs a few meters in diameter as far as 1 km from the vent, suggesting the eruption had stopped sometime in late November. Gas emissions decreased in June 2016. High-temperature areas around the crater continued to be detected. JMA reduced the warning statement for the island, specifying hazards were less severe “around the crater” (encompassing areas within 500 m), rather than more broadly “near the crater”.
Geological summary: The small island of Nishinoshima was recently enlarged when it was joined to several new islands that formed during an eruption in 1973-74. Water discoloration has been observed on several occasions since. The 700-m-wide 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.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 19-26 August 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.
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.
Stromboli, Aeolian Islands (Italy)
38.789°N, 15.213°E, Summit elev. 924 m
INGV reported that although unfavorable weather conditions often obscured views of the active vents at Stromboli during 16-22 August, some of the hourly explosions were recorded by a webcam. Explosions mainly occurred from two vents in the S part of the crater and one vent in the N part. Low-to-medium intensity explosions from the N vent ejected coarse material mixed with ash. The S vents were variably active, with some explosions ejecting coarse material tens of meters above the crater rim. The report noted that the rate of explosions, geochemistry, and seismicity were all at low, normal levels for Stromboli, with the exception of an increased number and intensity of very-long-period earthquakes on 22 August.
Geological 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, 924-m-high 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 from about 13,000 to 5000 years ago was followed by formation of the modern Stromboli edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of 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.
Suwanosejima, Ryukyu Islands (Japan)
29.638°N, 129.714°E, Summit elev. 796 m
Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that during 25-26 and 28-29 August explosions at Suwanosejima often generated ash plumes that rose to altitudes of 0.9-2.4 km (3,000-8,000 ft) a.s.l. and drifted W, SW, and SE.
Geological 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.
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