The Weekly Volcanic Activity Report: November 15 – 21, 2017

New activity/unrest was reported for 3 volcanoes between November 15 and 21, 2017. During the same period, ongoing activity was reported for 11 volcanoes.

New activity/unrest: Agung, Bali (Indonesia) | Oraefajokull, Iceland | Sarychev Peak, Matua Island (Russia).

Ongoing activity: Aira, Kyushu (Japan) | Bagana, Bougainville (Papua New Guinea) | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Kilauea, Hawaiian Islands (USA) | Kirishimayama, Kyushu (Japan) | Langila, New Britain (Papua New Guinea) | Sabancaya, Peru | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia.

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, notices of volcanic activity posted are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth’s volcanoes erupting during the week. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New activity/unrest

Agung, Bali (Indonesia)

8.343°S, 115.508°E, Summit elev. 2995 m

PVMBG reported that a phreatic eruption at Agung began at 1705 on 21 November, following a low-frequency tremor signal. An ash plume rose 700 m above the crater rim and drifted ESE. The Alert Level remained at 3 (on a scale of 1-4), and the exclusion zones remained intact (at 6 km, and an additional expansion to 7.5 km in the NNE, SE, S, and SW directions).

Geological summary: Symmetrical Agung stratovolcano, Bali’s highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means “Paramount,” rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.

Oraefajokull, Iceland

64.05°N, 16.633°W, Summit elev. 2010 m

The Icelandic Meteorological Office (IMO) reported that on 17 November the Aviation Color Code for Öræfajökull was raised to Yellow because satellite images and photos showed that a new ice cauldron had formed within the caldera the previous week. The new cauldron was about 1 km in diameter and 15-20 m deep, and signified a recent increase in geothermal activity. Scientists conducted an overflight on 18 November; in addition, while on the ground, they took water samples, measurements of electrical conductivity, and gas levels at the Kvíárjökull outlet-glacier, a valley glacier on the SE flank of Öræfajökull. There was no obvious sign of flooding in the Kvíá river. A sulfur odor, which had been reported for about a week, was also noted. An increase in the seismic activity was recorded for the last few months (the largest earthquake, an M 3.4, occurred on the 3 October), but was low for the past few days. IMO noted that there were no signs of an imminent volcanic eruption, though there was considerable uncertainty about how the situation will evolve.

Geological summary: Öraefajökull, Iceland’s highest peak, is a broad glacier-clad central volcano at the SE end of the Vatnajökull icecap. A 4 x 5 km subglacial caldera truncates the summit of the dominantly basaltic and rhyolitic volcano. The extensive summit icecap is drained through deep glacial valleys dissecting the SW-to-SE flanks. The largest-volume volcano in Iceland, 2119-m-high Öraefajökull was mostly constructed during Pleistocene glacial and interglacial periods. Holocene activity has been dominated by explosive summit eruptions, although flank lava effusions have also occurred. A major silicic eruption in 1362 CE was Iceland’s largest historical explosive eruption. It and another eruption during 1727-28 were accompanied by major jökulhlaups (glacier outburst floods) that caused property damage and fatalities.

Sarychev Peak, Matua Island (Russia)

48.092°N, 153.2°E, Summit elev. 1496 m

SVERT reported that weak steam-and-gas emissions from Sarychev Peak were observed on 13 November. Weather clouds prevented observations during 14-20 November. The Aviation Color Code remained at Green.

Geological summary: Sarychev Peak, one of the most active volcanoes of the Kuril Islands, occupies the NW end of Matua Island in the central Kuriles. The andesitic central cone was constructed within a 3-3.5-km-wide caldera, whose rim is exposed only on the SW side. A dramatic 250-m-wide, very steep-walled crater with a jagged rim caps the volcano. The substantially higher SE rim forms the 1496 m high point of the island. Fresh-looking lava flows, prior to activity in 2009, had descended in all directions, often forming capes along the coast. Much of the lower-angle outer flanks of the volcano are overlain by pyroclastic-flow deposits. Eruptions have been recorded since the 1760s and include both quiet lava effusion and violent explosions. Large eruptions in 1946 and 2009 produced pyroclastic flows that reached the sea.

Ongoing activity

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported that an explosion at Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) detected at 2207 on 13 November, ejected material as far as 1.3 km. The explosion vibrated structures in Kagoshima and Miyazaki prefectures. Poor weather conditions prevented views of a plume. An explosion at Showa Crater at 0955 on 14 November produced a plume that rose 1.3 km above the crater rim. Another explosion at Minamidake occurred at 2343 on 14 November, generating a plume that rose 1.3 km above the crater rim. Sulfur dioxide flux measured that same day was 1,400 tons per day, up from 400 tons per day on 10 November. Very small events at Minamidake were occasionally detected during 17-20 November. The Alert Level remained at 3 (on a 5-level scale).

Geological summary: The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan’s most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu’s largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

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 15-17 November ash plumes from Bagana rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted N, SW, SSW, and W.

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.

Cleveland, Chuginadak Island (USA)

52.825°N, 169.944°W, Summit elev. 1730 m

AVO reported that during 15-20 November elevated surface temperatures in Cleveland’s summit crater were sometimes identified in satellite data, consistent with lava at or near the surface; weather clouds sometimes prevented observations. No significant eruptive activity was detected by seismic or infrasound sensors. On 14 November a small explosion occurred from a vent in the middle of the dome. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geological summary: Beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited, dumbbell-shaped Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Cleveland is joined to the rest of Chuginadak Island by a low isthmus. The 1730-m-high Mount Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name for Mount Cleveland, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 Cleveland produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

Dukono, Halmahera (Indonesia)

1.693°N, 127.894°E, Summit elev. 1229 m

Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 15-21 November ash plumes from Dukono rose to altitudes of 2.1-2.3 km (7,000-8,000 ft) a.s.l. and drifted 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.

Ebeko, Paramushir Island (Russia)

50.686°N, 156.014°E, Summit elev. 1103 m

Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions on 16 November generated ash plumes that rose as high as 2 km (6,600 ft) a.s.l. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. Blocky lava flows extend west from Ebeko and SE from the neighboring Nezametnyi cone. The eastern part of the southern crater contains strong solfataras and a large boiling spring. The central crater is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters, on the outer flanks of the cone, and in lateral explosion craters.

Kilauea, Hawaiian Islands (USA)

19.421°N, 155.287°W, Summit elev. 1222 m

During 15-21 November HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Webcams recorded incandescence from long-active sources within Pu’u ‘O’o Crater and from a small lava pond in a pit on the W side of the crater. Surface lava flows were active above and on the pali, and on the coastal plain. On 17 November a field crew visited the Kamokuna ocean entry and observed only very sluggish, pasty flows in a few random spots and minor to no degassing in the usual places.

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.

Kirishimayama, Kyushu (Japan)

31.934°N, 130.862°E, Summit elev. 1700 m

JMA reported that during 13-20 November activity at Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, continued to be slightly elevated. White plumes rose 200 m above the crater rim. The Alert Level remained at 3 (on a scale of 1-5).

Geological summary: Kirishimayama is a large group of more than 20 Quaternary volcanoes located north of Kagoshima Bay. The late-Pleistocene to Holocene dominantly andesitic group consists of stratovolcanoes, pyroclastic cones, maars, and underlying shield volcanoes located over an area of 20 x 30 km. The larger stratovolcanoes are scattered throughout the field, with the centrally located, 1700-m-high Karakunidake being the highest. Onamiike and Miike, the two largest maars, are located SW of Karakunidake and at its far eastern end, respectively. Holocene eruptions have been concentrated along an E-W line of vents from Miike to Ohachi, and at Shinmoedake to the NE. Frequent small-to-moderate explosive eruptions have been recorded since the 8th century.

Langila, New Britain (Papua New Guinea)

5.525°S, 148.42°E, Summit elev. 1330 m

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 15-16 November ash plumes from Langila rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted S and SW.

Geological summary: Langila, one of the most active volcanoes of New Britain, consists of a group of four small overlapping composite basaltic-andesitic cones on the lower eastern flank of the extinct Talawe volcano. Talawe is the highest volcano in the Cape Gloucester area of NW New Britain. A rectangular, 2.5-km-long crater is breached widely to the SE; Langila volcano was constructed NE of the breached crater of Talawe. An extensive lava field reaches the coast on the north and NE sides of Langila. Frequent mild-to-moderate explosive eruptions, sometimes accompanied by lava flows, have been recorded since the 19th century from three active craters at the summit of Langila. The youngest and smallest crater (no. 3 crater) was formed in 1960 and has a diameter of 150 m.

Sabancaya, Peru

15.787°S, 71.857°W, Summit elev. 5960 m

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya increased compared to the previous week; there was an average of 82 explosions recorded per day during 13-19 November. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 4 km above the crater rim and drifted 40 km NE, N, and NW. The MIROVA system detected eight thermal anomalies. The sulfur dioxide flux was high, at 3,103 tons per day on 13 November. The report noted that the public should not to approach the crater within a 12-km radius.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning “tongue of fire” in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Sheveluch, Central Kamchatka (Russia)

56.653°N, 161.36°E, Summit elev. 3283 m

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images on 11 November; weather clouds prevented observations on the other days during 12-17 November. 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 observations by PVMBG, satellite and webcam images, and model data, the Darwin VAAC reported that during 15-19 November ash plumes from Sinabung rose 4.3-4.9 km (14,000-16,000 ft) a.s.l. and drifted NW, W, and SW. The Alert Level remained at 4 (on a scale of 1-4).

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 andesitic-to-dacitic edifice 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

Robust steaming, elevated seismicity at Great Sitkin volcano, Alaska

The Alaska Volcano Observatory (AVO) has raised the Aviation Color Code and Volcano Alert Level to Yellow/Advisory on November 22, 2017, after recent reports of robust steaming and a several month period of elevated earthquake activity. Historical eruptions have been recorded at Great Sitkin since the late-19th century. Its last eruptive episode started in February 1974 and lasted 7 months.

Recent observations of a robust steam plume and a period of gradually increasing seismicity over several months indicate that Great Sitkin Volcano has become restless and is exhibiting behavior that is above background levels, AVO reported 19:57 UTC on November 22, 2017. 

Photographs of the volcano taken by local observers on Sunday, November 19 show a light-colored vapor plume rising about 300 m (1 000 feet) above the vent area and extending about 15 – 20 km (9 – 12 miles) to the south. Nothing unusual was observed in seismic or infrasound data around the time the photographs were taken and nothing noteworthy has been observed in satellite data since the emissions were observed, AVO added. 

Great Sitkin on November 19, 2017

Great Sitkin on November 19, 2017. Credit: Alain Beauparlant / AVO

An increased number of small earthquakes was evident as early as late July 2016, and since then the level of seismic activity has fluctuated at low levels but has exhibited a gradual overall increase most notable since June 2017. Seismic activity to date has been characterized by earthquakes that are typically less than magnitude 1.0 and range in depth from near the summit of the volcano to 30 km (18 miles) below sea level. Most earthquakes are in one of two clusters, beneath the volcano’s summit or just offshore the northwest coast of the island. The largest earthquake so far was a magnitude 2.8 on September 29, 2017.

Possible explosion signals were observed in seismic data on January 10 and July 21 of this year, but no confirmed emissions were observed locally or detected in infrasound data or satellite imagery. Great Sitkin has experienced at least one other episode of unrest characterized by vigorous steaming. This last occurred in 1953 but no subsequent eruptive activity developed. Minor steaming in the vicinity of the 1974 lava dome was observed in 1986 and in 2012 but no associated eruptive activity occurred. 

Great Sitkin on November 19, 2017

Great Sitkin on November 19, 2017. Credit: Alain Beauparlant / AVO

The current unrest is likely the result of magma intrusion beneath the volcano. Typically, such intrusions release gas, which can increase stress in the crust and lead to an increase in the number of earthquakes. If gases build up near the surface, they may be released suddenly in small explosions or robust emissions. It is possible, but not certain, that the volcano may eventually erupt. Prior to a significant eruptive event an even greater increase in seismicity should occur as magma rises to shallower levels in the crust. An ash-producing eruption similar to the most recent historical eruption in 1974 could generate airborne ash that may pose hazards to aircraft. Ash fallout on the nearby community of Adak and the surrounding ocean may also occur.

Great Sitkin on November 19, 2017

Great Sitkin on November 19, 2017. Credit: Alain Beauparlant / AVO

The last eruption of this volcano started February 19, 1974 and ended on September 16 of the same year  ± 15 days. It had Volcanic Explosivity Index of 2 (of 7).

Great Sitkin Volcano is monitored by a five-station seismic network on Great Sitkin Island and with additional seismic stations on the nearby islands of Igitkin, Adak, Kagalaska, and Kanaga. A six-element infrasound array to detect explosions (atmospheric pressure waves), was installed on Adak Island in June 2017. AVO also uses satellite imagery to monitor Great Sitkin Volcano.

Geological summary

The 1740-m-high (5 708 feet) Great Sitkin volcano forms much of the northern side of Great Sitkin Island. A younger parasitic volcano capped by a small, 0.8 x 1.2 km (0.49 – 0.74 miles) ice-filled summit caldera was constructed within a large late-Pleistocene or early Holocene scarp formed by massive edifice failure that truncated an ancestral volcano and produced a submarine debris avalanche. Deposits from this and an older debris avalanche from a source to the south cover a broad area of the ocean floor north of the volcano.

The 1740-m-high summit lies along the eastern rim of the younger collapse scarp. Deposits from an earlier caldera-forming eruption of unknown age cover the flanks of the island to a depth up to 6 meters (19.7 feet). The small younger caldera was partially filled by lava domes emplaced in 1945 and 1974, and five small older flank lava domes, two of which lie on the coastline, were constructed along northwest- and NNW-trending lines. Hot springs, mud pots, and fumaroles occur near the head of Big Fox Creek, south of the volcano. Historical eruptions have been recorded at Great Sitkin since the late-19th century.

Featured image: Great Sitkin, as seen on the morning of November 19, 2017, from Adak. Credit: AVO