The Weekly Volcanic Activity Report: October 30 - November 5, 2019

The Weekly Volcanic Activity Report: October 30 - November 5, 2019

New activity/unrest was reported for 4 volcanoes from October 30 to November 5, 2019. Ongoing activity was reported for 13 volcanoes during the same period.

New activity/unrest: Kikai, Japan | Klyuchevskoy, Central Kamchatka (Russia) | Metis Shoal, Tonga Islands | Shishaldin, Fox Islands (USA).

Ongoing activity: Aira, Kyushu (Japan) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Ibu, Halmahera (Indonesia) | Karangetang, Siau Island (Indonesia) | Kerinci, Indonesia | Sabancaya, Peru | Sangeang Api, Indonesia | Semeru, Eastern Java (Indonesia) | Sheveluch, Central Kamchatka (Russia) | Stromboli, Aeolian Islands (Italy) | Suwanosejima, Ryukyu Islands (Japan) | Yasur, Vanuatu.

New activity/unrest

Kikai, Japan

30.793°N, 130.305°E, Elevation 704 m

An eruption at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was detected at 1735 on 2 November, prompting JMA to raise the Alert Level to 2 (on a 5-level scale). A grayish-white plume rose 1 km above the Iodake crater rim. The report noted that the number of volcanic earthquakes has been low, with no variations before or after the event. The next day during an overflight conducted by the Coast Guard and the Japan Meteorological Agency Mobile Survey Team (JMA-MOT) observers noted no changes to the geothermal field and no new deposits from the event the day before. Views of the crater were obscured by white plumes rising 300 m above the crater rim.

Geological summary: Kikai is a mostly submerged, 19-km-wide caldera near the northern end of the Ryukyu Islands south of Kyushu. Kikai was the source of one of the world's largest Holocene eruptions about 6300 years ago. Rhyolitic pyroclastic flows traveled across the sea for a total distance of 100 km to southern Kyushu, and ashfall reached the northern Japanese island of Hokkaido. The eruption devastated southern and central Kyushu, which remained uninhabited for several centuries. Post-caldera eruptions formed Iodake lava dome and Inamuradake scoria cone, as well as submarine lava domes. Historical eruptions have occurred in the 20th century at or near Satsuma-Iojima (also known as Tokara-Iojima), a small 3 x 6 km island forming part of the NW caldera rim. Showa-Iojima lava dome (also known as Iojima-Shinto), a small island 2 km east of Tokara-Iojima, was formed during submarine eruptions in 1934 and 1935. Mild-to-moderate explosive eruptions have occurred during the past few decades from Iodake, a rhyolitic lava dome at the eastern end of Tokara-Iojima.

Klyuchevskoy, Central Kamchatka (Russia)

56.056°N, 160.642°E, Elevation 4754 m

KVERT reported that ash plumes and steam-and-gas plumes with some ash drifted 130 km SW on 25 October according to video and satellite data. A weak thermal anomaly was identified in satellite images during 26-27 and 30 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. This volcano is located within the Volcanoes of Kamchatka, a UNESCO World Heritage property.

Metis Shoal, Tonga Islands

19.18°S, 174.87°W, Elevation 43 m

GeoNet reported that by 1 November the eruption at Metis Shoal (Lateiki) had formed an elongated island, with no visible evidence of the old 1995 dome. According to a news article the new island is about 100 m wide and 400 m long, and had emerged at a location 120 m away from the former island. The article noted that the eruption had ceased.

Geological summary: Metis Shoal, a submarine volcano midway between the islands of Kao and Late, has produced a series of ephemeral islands since the first confirmed activity in the mid-19th century. An island, perhaps not in eruption, was reported in 1781 and subsequently was eroded away. During periods of inactivity following 20th-century eruptions, waves have been observed to break on rocky reefs or sandy banks with depths of 10 m or less. Dacitic tuff cones formed during the first 20th-century eruptions in 1967 and 1979 were soon eroded beneath the sea surface. An eruption in 1995 produced an island with a diameter of 280 m and a height of 43 m following growth of a lava dome above the surface.

Shishaldin, Fox Islands (USA)

54.756°N, 163.97°W, Elevation 2857 m

AVO reported that by 28 October two stalled lava flows extended as far as 1.8 km down Shishaldin’s NW flank, lahars had traveled at least 4 km down the NW flank, and trace ash deposits on the N flank were identified in satellite images. Activity paused during 29-30 October but resumed on 31 October. Numerous small explosions were detected by the local seismic network during 31 October-1 November and incandescence was visible in webcam images. There was no evidence of active lava flows outside of the summit crater. During 1-2 November seismicity remained elevated characterized by periods of high-amplitude tremor. Small explosions were recorded in seismic and infrasound data. Elevated surface temperatures were detected in satellite images and incandescence was observed in webcam images overnight. A pilot observed a lava flow in the morning of 2 November. Sporadic incandescence recorded by the webcam overnight during 2-3 November suggested minor explosive activity and/or lava fountaining. On 3 November lava overflowed the summit crater and traveled at least 400 m down the NW flank and 300 m down the SE flank. By 4 November the flow on the NW flank had branched and lengthened to 1 km. Lahars were as long as 2 km on the N and S flanks. Spatter deposits from explosions or fountaining were visible on the summit cone. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geological summary: The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is blanketed by massive aa lava flows. Frequent explosive activity, primarily consisting of strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century. This volcano is located within the Aleutian Islands, a UNESCO Biosphere Reserve property.

Ongoing Activity

Aira, Kyushu (Japan)

31.593°N, 130.657°E, Elevation 1117 m

JMA reported that incandescence from Minamidake crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 28 October-5 November. There were 32 explosions and 16 non-explosive eruptive events detected by the seismic network. Eruption plumes rose as high as 2.8 km above the crater rim and large blocks were ejected as far as 1.3 km away. 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.

Dukono, Halmahera (Indonesia)

1.693°N, 127.894°E, Elevation 1229 m

Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 30 October-5 November ash plumes from Dukono rose to an altitude of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE, E, and SE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

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, Elevation 1103 m

Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 25-26 and 29-30 October that sent ash plumes up to 2.5 km (8,200 ft) a.s.l. Ash plumes drifted E and NE. A weak thermal anomaly was identified in satellite images on 29 October. 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.

Ibu, Halmahera (Indonesia)

1.488°N, 127.63°E, Elevation 1325 m

PVMBG reported that during 1-5 November white-and-gray plumes from Ibu rose 200-800 m above the summit and drifted E and N. The Alert Level remained at 2 (on a scale of 1-4), and 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.

Karangetang, Siau Island (Indonesia)

2.781°N, 125.407°E, Elevation 1797 m

PVMBG reported that during 1-5 November lava continued to effuse from Karangetang’s Main Crater (S), traveling as far as 1.5 km down the Nanitu, Pangi, and Sense drainages on the SW and W flanks. Sometimes dense white plumes rose to 200 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Geological summary: Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi island. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.

Kerinci, Indonesia

1.697°S, 101.264°E, Elevation 3800 m

PVMBG reported that at 0614 on 30 October a brownish-white ash emission from Kerinci rose around 800 m above the summit and drifted NE, E, and SE. Brownish ash emissions rose 800 m and drifted WSW at 1721 on 30 October and to 500 m and drifted ESE at 0543 on 1 November. An eruptive event at 0553 on 2 November generated a brown ash emission that rose 500 m and drifted ESE. During 3-5 November brown ash plumes rose 100-500 m. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

Geological summary: Gunung Kerinci in central Sumatra forms Indonesia's highest volcano and is one of the most active in Sumatra. It is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. There is a deep 600-m-wide summit crater often partially filled by a small crater lake that lies on the NE crater floor, opposite the SW-rim summit. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. Frequently active, Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838. This volcano is located within the Tropical Rainforest Heritage of Sumatra, a UNESCO World Heritage property.

Sabancaya, Peru

15.787°S, 71.857°W, Elevation 5960 m

Instituto Geofísico del Perú (IGP) reported that an average of 28 low-to-medium intensity explosions per day occurred at Sabancaya during 28 October-3 November. Gas-and-ash plumes rose as high as 2 km above the summit and drifted W, SW, and S. There were nine thermal anomalies identified in satellite data. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of 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.

Sangeang Api, Indonesia

8.2°S, 119.07°E, Elevation 1912 m

The Darwin VAAC reported that during 30-31 October and 3-4 November discrete and short-lived ash emissions from Sangeang Api rose 2.7-3.5 km (9,000-11,000 ft) a.s.l. and drifted NW, W, and SW. Thermal anomalies were visible on 3 and 5 November. The Alert Level remained at 2 (on a scale of 1-4).

Geological summary: Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, Doro Api and Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent historical eruptions have been recorded since 1512, most of them during in the 20th century.

Semeru, Eastern Java (Indonesia)

8.108°S, 112.922°E, Elevation 3657 m

The Darwin VAAC reported that on 30 October an ash plume from Semeru rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted SE and S based on satellite images and weather models. The Alert Level remained at 2 (on a scale of 1-4).

Geological summary: Semeru, the highest volcano on Java, and one of its most active, lies at the southern end of a volcanic massif extending north to the Tengger caldera. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises above coastal plains to the south. Gunung Semeru was constructed south of the overlapping Ajek-ajek and Jambangan calderas. A line of lake-filled maars was constructed along a N-S trend cutting through the summit, and cinder cones and lava domes occupy the eastern and NE flanks. Summit topography is complicated by the shifting of craters from NW to SE. Frequent 19th and 20th century eruptions were dominated by small-to-moderate explosions from the summit crater, with occasional lava flows and larger explosive eruptions accompanied by pyroclastic flows that have reached the lower flanks of the volcano. This volcano is located within the Bromo Tengger Semeru-Arjuno, a UNESCO Biosphere Reserve property.​

Sheveluch, Central Kamchatka (Russia)

56.653°N, 161.36°E, Elevation 3283 m

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 25 October-1 November. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geological summary: The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 km3 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, Elevation 924 m

INGV reported that during 30 October-5 November activity at Stromboli was characterized by ongoing Strombolian activity and degassing from multiple vents within the crater terrace. Explosions originated at a rate of 2-13 per hour from vents in Area N (north crater area) and at a rate of 7-16 per hour from vents in Area C-S (south central crater area). Explosions from Area N ejected lapilli and bombs no more than 175 m high, while explosions at Area C-S ejected tephra to heights under 250 m.

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 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 took place between about 13,000 and 5,000 years ago. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5,000 years ago due to 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. This volcano is located within the Isole Eolie (Aeolian Islands), a UNESCO World Heritage property.

Suwanosejima, Ryukyu Islands (Japan)

29.638°N, 129.714°E, Elevation 796 m

JMA reported that at 1225 on 19 October a very small eruptive event at Suwanosejima’s Ontake Crater generated a gray plume that rose 300 m above the crater rim. A small amount of ash fell in Toshima, 4 km SW. Very small eruptions during 29-30 October generated grayish-white plumes that rose 800 m. Ashfall was reported in Toshima on 29 October. The Alert Level remained at 2 (on a 5-level scale).

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.

Yasur, Vanuatu

19.532°S, 169.447°E, Elevation 361 m

On 31 October the Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that recent observations and data from Yasur’s seismic network confirmed ongoing sometimes strong explosions. The Alert Level remained at 2 (on a scale of 0-4). VMGD reminded residents and tourists that hazardous areas were near and around the volcanic crater, within a 395-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. The active cone 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.

Source: GVP

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