New activity/unrest was reported for 6 volcanoes between October 12 and 18, 2016. During the same period, ongoing activity was observed at 7 volcanoes.
New activity/unrest: Asosan, Kyushu (Japan) | Bulusan, Luzon (Philippines) | Colima, Mexico | Karymsky, Eastern Kamchatka (Russia) | Ulawun, New Britian (Papua New Guinea) | Yasur, Vanuatu.
Ongoing activity: Bagana, Bougainville (Papua New Guinea) | Dukono, Halmahera (Indonesia) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Nevado del Ruiz, Colombia | Sheveluch, Central Kamchatka (Russia) | Turrialba, Costa Rica.
Asosan, Kyushu (Japan)
32.884°N, 131.104°E, Summit elev. 1592 m
JMA reported that no further explosions were detected after the 7-8 October eruption at Asosan’s Nakadake Crater; white plumes rose as high as 400 m above the crater rim during 11-17 October. The Alert Level remained at 3 (on a scale of 1-5).
Geological summary: The 24-km-wide Asosan caldera was formed during four major explosive eruptions from 300,000 to 90,000 years ago. These produced voluminous pyroclastic flows that covered much of Kyushu. The last of these, the Aso-4 eruption, produced more than 600 cu km of airfall tephra and pyroclastic-flow deposits. A group of 17 central cones was constructed in the middle of the caldera, one of which, Nakadake, is one of Japan's most active volcanoes. It was the location of Japan's first documented historical eruption in 553 AD. The Nakadake complex has remained active throughout the Holocene. Several other cones have been active during the Holocene, including the Kometsuka scoria cone as recently as about 210 CE. Historical eruptions have largely consisted of basaltic to basaltic-andesite ash emission with periodic strombolian and phreatomagmatic activity. The summit crater of Nakadake is accessible by toll road and cable car, and is one of Kyushu's most popular tourist destinations.
Bulusan, Luzon (Philippines)
12.77°N, 124.05°E, Summit elev. 1565 m
PHIVOLCS reported that during 12-16 October the seismic network at Bulusan recorded 2-6 volcanic earthquakes per day. During 12-13 October steam plumes rose as high as 500 m above the active vents and drifted SE and SSE. The network recorded 24 volcanic earthquakes from 16 to 17 October. At 0736 on 17 October a 24-minute-long phreatic explosion at the SE vent generated an ash plume that rose 1 km.
PHIVOLCS noted that while the SE vents are within the 4-km-radius Permanent Danger Zone (PDZ) they are part of a fissure that extends 2 km down the upper S flank. Eruptions from this area pose a greater risk to the populated barangays of Mapaso and Patag in Irosin, and San Roque in Bulusan. In response the Extended Danger Zone (EDZ) was increased and as of 18 October stretched an additional 2 km past the PDZ. The Alert Level remained at 1, indicating abnormal conditions and a 4-km-radius Permanent Danger Zone (PDZ).
Geological summary: Luzon's southernmost volcano, Bulusan, was constructed along the rim of the 11-km-diameter dacitic-to-rhyolitic Irosin caldera, which was formed about 36,000 years ago. Bulusan lies at the SE end of the Bicol volcanic arc occupying the peninsula of the same name that forms the elongated SE tip of Luzon. A broad, flat moat is located below the topographically prominent SW rim of Irosin caldera; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of 1565-m-high Bulusan volcano is unvegetated and contains a 300-m-wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century.
19.514°N, 103.62°W, Summit elev. 3850 m
Based on webcam and satellite images, and information from Colima Towers, the Washington VAAC reported that ash plumes from Colima rose to altitudes of 5.2-7 km (17,000-23,000 ft) a.s.l. and drifted 35-215 km W, NW, N, and NE during 11-18 October.
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.
Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Summit elev. 1513 m
Based on satellite image analysis, KVERT reported that during 7-8 October gas, steam, and ash plumes rose from Karymsky and drifted 390 km E and SE. A weak thermal anomaly was detected over the volcano on 7 and 12 October. The Aviation Color Code remained at Orange.
Geological 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.
Ulawun, New Britian (Papua New Guinea)
5.05°S, 151.33°E, Summit elev. 2334 m
RVO reported that during 1 September-15 October white vapor plumes with varying densities rose from Ulawun, although on 12 October pale gray ash plumes rose from the vent. A report from officers at Hargy Palm Oil dated 13 October stated that a “minor eruption” had occurred after 1800 on 12 October, and that there were a few low noises from the volcano and nighttime glow during 12-13 October. RVO noted that the seismic record did not indicate an eruption.
Seismicity was at a low to moderate level, dominated by small low-frequency volcanic earthquakes. RSAM values increased and by mid-October were at the highest values (peak of 200) so far in 2016. Based on analyses of satellite imagery, the Darwin VAAC reported that during 16-17 October ash plumes rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SW and W.
Geological summary: The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun volcano, also known as the Father, rises above the north coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1000 m of the 2334-m-high Ulawun volcano is unvegetated. A prominent E-W-trending escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and eastern flanks. A steep-walled valley cuts the NW side of Ulawun volcano, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
19.53°S, 169.442°E, Summit elev. 361 m
On 15 October the Vanuatu Geohazards Observatory stated that the Alert Level for Yasur was raised to 3 (on a scale of 0-4), noting that explosions could become more intense. The Alert Level was lowered back to 2 on 18 October. VGO reminded residents and tourists that hazardous areas were near and around the volcanic crater, within a 600-m-radius permanent exclusion zone, and that volcanic ash and gas could reach areas impacted by trade winds.
Geological 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. Yasur 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.
Bagana, Bougainville (Papua New Guinea)
6.137°S, 155.196°E, Summit elev. 1855 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 15 October an ash plume from Bagana rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted over 90 km SW. During 18-19 October ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 65-120 km SW and NW.
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.
Dukono, Halmahera (Indonesia)
1.693°N, 127.894°E, Summit elev. 1229 m
Based on analyses of satellite imagery, ground observations, a Volcano Notice to Aviation (VONA), and model data, the Darwin VAAC reported that during 12-18 October ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted as far as 225 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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m
During 12-18 October HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent; on 15 October the lake rose high enough to produce small lobes of lava that flowed E and W on the Halema’uma’u floor. 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 near Kamokuna.
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 7-14 October. Gas-and-steam emissions with variable amounts of ash rose from the summit crater and from the cinder cone in the Apakhonchich drainage on the E flank. A lava flow traveled down the Apakhonchich drainage. Satellite images showed a large and bright daily thermal anomaly at the volcano, and ash plumes from explosions that rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. and drifted 300 km N, NE, E, and SE during 7-12 October. 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.
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 11-17 October seismicity at Nevado del Ruiz was characterized by a decrease in the number and magnitude of earthquakes compared to the previous week. Gas-and-ash plumes were visible on 12 and 13 October. On 15 October gas, steam, and ash plumes rose as high as 2.5 km above the crater and drifted NW. The number of long-period events increased during 1800-2300 on 17 October; some of the signals were associated with gas-and-ash emissions. Significant amounts of water vapor and gas rose from the crater. 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.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m
KVERT reported that during 7-14 October 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. According to video and satellite data, explosions generated ash plumes that rose to an altitude of 5.5 km (18,000 ft) a.s.l. and drifted 65 km N, NE, E, and SE during 10 and 12-13 October. 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.
Turrialba, Costa Rica
10.025°N, 83.767°W, Summit elev. 3340 m
OVSICORI-UNA reported that tremor levels and ash emissions at Turrialba decreased around 1700 on 11 October. A small eruption occurred at 2132; ashfall was reported in Guadeloupe. Another event was recorded at 1620 on 12 October but weather conditions obscured views of any resulting emissions. On 13 October long-period earthquakes were associated with ash emissions that rose no higher than 500 m above the vent. Tremor amplitude increased around 1029 on 13 October and remained variably elevated at least through 15 October; emissions occurred at around 1029 and 2006 on 13 October, and almost continuously during 14-15 October, producing ash plumes that rose as high as 1 km. Ashfall and a sulfur odor was reported in areas downwind, near the volcano. On 16 October OVSICORI-UNA noted that the almost constant ash emission in the previous few days affected the operation and communication of various scientific instruments installed at the top of the volcano and surrounding areas; communication with two seismic stations located near the summit was lost. Webcams showed continuing ash emissions rising as high as 1 km during 16-18 October.
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.