New activity/unrest was reported for 5 volcanoes between October 5 and 11, 2016. During the same period, ongoing activity was reported for 12 volcanoes.
New activity/unrest: Asosan,Kyushu (Japan) | Colima, Mexico | Karymsky, Eastern Kamchatka (Russia) | Tengger Caldera, Eastern Java (Indonesia) | Ulawun, New Britian (Papua New Guinea).
Ongoing activity: Bulusan, Luzon (Philippines) | Dukono, Halmahera (Indonesia) | Etna, Sicily (Italy) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Nevado del Ruiz, Colombia | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Suwanosejima, Ryukyu Islands (Japan) | Turrialba, Costa Rica | Yasur, Vanuatu.
Asosan, Kyushu (Japan)
32.884°N, 131.104°E, Elevation 1592 m
JMA reported that explosive eruptions at Asosan’s Nakadake Crater occurred at 2152 on 7 October and 0146 on 8 October, after a period of deformation was detected. Inclement weather prevented visual observations, although satellite images showed the 8 October ash plume rising to an altitude of 11 km (36,100 ft)a.s.l. The Alert Level was raised to 3 (on a scale of 1-5). During an overflight scientists observed high temperatures in the crater, and white plumes rising 300 m above the rim. Ash deposits extended as far as 1.6 km on the NW flank and 1 km on the SE flank, and were abundant on the NE flank. Ashfall 3 cm thick was reported at the Aso police station 6 km NE. According to news articles, ashfall was reported as far away as 320 km, and some farmers 6-8 km away reported damage to their greenhouses, and a window was cracked from tephra at a youth center 5 km away. Samples analyzed by The National Institute of Advanced Industrial Science and Technology (AIST) and the National Research Institute for Earth Science and Disaster Prevention (NIED) revealed a 10% juvenile magmacomponent, and that the explosions were possibly phreatomagmatic.
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.
19.514°N, 103.62°W, Elevation 3850 m
Based on webcam and satellite images, and information from the Mexico City MWO, the Washington VAAC reported that ash plumes from Colima rose to altitudes of 4.3-6.1 km (14,000-20,000 ft) a.s.l. during 5-6 and 8-11 October. Thermal anomalies were observed on most days; a strong hotspot consistent with lava flow was observed on 9 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, Elevation 1513 m
Based on satellite image analysis, KVERT reported that during 5-7 October gas-and-steam plumes containing small amounts of ash rose from Karymsky and drifted 100 km SE. The Aviation Color Code was raised to Yellow. Ash emissions continued to drift SE on 8 October; the total length of the ash plume grew to 388 km. The Aviation Color Code was raised to 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.
Tengger Caldera, Eastern Java (Indonesia)
7.942°S, 112.95°E, Elevation 2329 m
Based on analyses of satellite images, the Darwin VAAC reported that during 5-6 October ash plumes from Tengger Caldera’s Bromo cone rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted almost 40 km SW and W. On 7 October PVMBG reported that activity at Bromo cone remained high. Grayish-white and blackish-brown plumes rose 100-300 m above the crater rim and drifted NW.
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.
Ulawun, New Britian (Papua New Guinea)
5.05°S, 151.33°E, Elevation 2334 m
Based on analyses of satellite imagery and observations from RVO, the Darwin VAAC reported that during 11-12 October ash plumes from Ulawun rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted 65 km WSW 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.
Ongoing activity Bulusan, Luzon (Philippines)
12.77°N, 124.05°E, Elevation 1565 m
On 5 October, PHIVOLCS reported that since the morning of 30 September a fissure on Bulusan’s SE flank had been venting low steam plumes with minor amounts of ash. Also during this time a strong sulfur odor was noticed in barangay Mapaso, Irosin. A 15-minute-long, minor phreatic eruption was recorded by the seismic network on the morning of 6 October. Weather clouds prevented visual observations. Ashfall was reported in some areas of Gubat and rumbling was noted in barangay San Roque, Bulusan. 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.
Dukono, Halmahera (Indonesia)
1.693°N, 127.894°E, Elevation 1229 m
Based on analyses of satellite imagery, information from PVMBG, and model data, the Darwin VAAC reported that during 5 and 7-11 October ash plumes from Dukono rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted NE, E, SE, and S.
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.
Etna, Sicily (Italy)
37.734°N, 15.004°E, Elevation 3330 m
On 10 October INGV reported that during the past few weeks high-temperature degassing had continued from a vent that had opened on 7 August in the E portion of Etna’s Voragine crater. In addition minor and infrequent ash emissions from old pulverized rock rose from a vent located on the upper E flank of the New Southeast Crater cone. In the early afternoon of 10 October an explosion occurred at the Bocca Nuova crater, in an area between the crater and the nearby Voragine crater. The explosion was recorded at 1526, and produced a distinct thermal anomaly and an ash puff that rose a few hundred meters. During the next few hours similar seismic events were detected although weather cloud cover prevented visual observations.
Geological summary: Mount Etna, towering above Catania, Sicily’s second largest city, has one of the world’s longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Elevation 1222 m
During 5-11 October HVO reported that the lava lake continued to rise and fall, circulate, and spatter in Kilauea’s Overlook vent. 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; only the E side of the entry was active. Scattered breakouts were active 2 km inland from the coast. National Park Service staff reported that a collapse of the E part of the lava delta occurred sometime between 2-6 October.
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, Elevation 4754 m
KVERT reported that a Strombolian eruption at Klyuchevskoy continued during 30 September-7 October. Gas-and-steam emissions with variable amounts of ashrose 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 260 km E. 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, Elevation 5279 m
Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 4-10 October the number and magnitude of volcano-tectonic earthquakes at Nevado del Ruiz increased compared to the previous week. Long-period and very-long-period signals as well as pulses of tremor were also recorded. Significant amounts of water vapor and gas rose from the crater. At 1746 on 5 October an episode of volcanic tremor was associated with ashemissions recorded by area webcams. Gas, steam, and ash plumes rose 2 km above the crater on 8 October and drifted NE. 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, Elevation 3772 m
On 6 October a 16-m-wide, 1.5-m-deep lahar triggered by rainfall descended the Cabello de Ángel drainage, a tributary of the Nimá I river drainage on Santa María’s S flank, carrying tree trunks and blocks up to 1 m in diameter. The lahar had a minor sulfur odor. In the morning on 10 October two explosions from the Santiaguito lava-dome complex generated an ash plume that rose 800 m and drifted SW. During 10-11 October there were 13 explosions, producing ash plumes that rose as high as 500 m and drifted SW.
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, Elevation 3283 m
KVERT reported that during 30 September-7 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. Video and satellite data showed that during 2-3 and 5-6 October. Re-suspended ash formed a plume that drifted about 280 km E and SE during 3-4 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.
3.17°N, 98.392°E, Elevation 2460 m
Based on ground observations from PVMBG, the Darwin VAAC reported that on 5 October an ash plume from Sinabung rose to an altitude of 3.3 km (11,000 ft)a.s.l. and drifted SE. On 12 October an ash plume drifted E at an altitude of 4.6 km (15,000 ft) a.s.l.
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.
Suwanosejima, Ryukyu Islands (Japan)
29.638°N, 129.714°E, Elevation 796 m
Based on JMA notices and satellite-image analyses, the Tokyo VAAC reported that on 6 October an explosion at Suwanosejima generated ash plumes that rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted E.
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.
Turrialba, Costa Rica
10.025°N, 83.767°W, Elevation 3340 m
OVSICORI-UNA reported that during 4-5 October tremor levels at Turrialba were low. At 0600 on 6 October tremor levels rose a small amount, and coincided with an emission with minor amounts of ash that rose 1 km and drifted N and NE. Tremor levels again rose at 1054, coinciding with another ash emission. Tremor amplitude varied during 7-11 October, and almost continuous ash emissions rose no more than 500 m and drifted N, NW, W, and SW. Minor ashfall and a sulfur odor were reported in some local areas downwind.
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.
19.53°S, 169.442°E, Elevation 361 m
On 10 October the Vanuatu Geohazards Observatory stated that the Alert Level for Yasur remained at 2 (on a scale of 0-4) and that explosions continued to be intense. 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.
Featured image: GVP