New activity/unrest was observed at 4 volcanoes from April 8 – 14, 2015. During the same period, ongoing activity was observed at 14 volcanoes.
New activity/unrest: Chirinkotan, Kuril Islands (Russia) | Semeru, Eastern Java (Indonesia) | Tungurahua , Ecuador | Villarrica, Chile.
Ongoing activity: Aira, Kyushu (Japan) | Chirpoi, Kuril Islands (Russia) | Colima, Mexico | Dukono, Halmahera (Indonesia) | Etna, Sicily (Italy) | Karymsky, Eastern Kamchatka (Russia) | Kerinci, Indonesia | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Popocatepetl, Mexico | San Miguel, El Salvador | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Slamet, Central Java (Indonesia) | Suwanosejima, Ryukyu Islands (Japan) | Ubinas, Peru | Zhupanovsky, Eastern Kamchatka (Russia).
Chirinkotan, Kuril Islands (Russia)
48.98°N, 153.48°E, Elevation 724 m
SVERT reported that on 6 April a thermal anomaly over Chirinkotan was detected in satellite images. Weak gas-and-steam emissions were noted on 8 April. Cloud cover prevented views of the volcano on the other days during 7-13 April. The Aviation Color Code remained at Yellow.
Geologic summary: The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.
Semeru, Eastern Java (Indonesia)
8.108°S, 112.92°E, Elevation 3676 m
PVMBG reported that during 1 January-10 April white and gray plumes were observed rising above Semeru even though inclement weather sometimes prevented visual observations. During January white plumes and nine instances of grayish-white plumes rose 200-500 m above the crater. Seven incandescent avalanches from a lava-flow front traveled at most 300 m down the flank. In February white plumes and 19 instances of grayish-white plumes rose 200-600 m above the crater. Eruption sounds were reported five times. In March white plumes and 21 instances of grayish-white plumes rose 200-500 m above the crater. Nine explosions were heard. During 1-10 April there were 18 instances of grayish-white emissions. Seismicity from 1 January through 10 April fluctuated, and was dominated by emission and explosion signals. The Alert Level remained at 2 (on a scale of 1-4) and the public was reminded not to approach the crater within a 4-km radius.
Geologic 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 abruptly to 3676 m 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. Semeru has been in almost continuous eruption since 1967.
1.467°S, 78.442°W, Elevation 5023 m
IG reported that minor ash emissions from Tungurahua were seen almost daily during 8-14 April, although cloud cover often prevented visual observations. During 7-8 April ash emissions rose 500-800 m above the crater and drifted NW, W, and SW; ashfall was reported in Quero (20 km NW), Guanto, Guazmo, Mirador, Santuario, and in the sectors of El Manzano (8 km SW), Pillate (8 km W), and Choglontus (13 km WSW). Ashfall was reported in Chonglontus on 9 April. Later that day a plume with low ash content drifted W. During 9-10 April seismicity increased to a high level, and "drumbeat" events were detected there for the first time during 16 years of monitoring. Ashfall was reported in El Manzano and Chonglontus. On 11 April an emission with low ash content drifted W. On 13 April a steam-and-ash plume drifted W and SW, causing ashfall in El Manzano. On 14 April an emission with low ash content drifted W; ash fell in Mapayacu.
Geologic summary: Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater, accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.
39.42°S, 71.93°W, Elevation 2847 m
OVDAS-SERNAGEOMIN reported that infrasound data indicated explosions at Villarrica on 8 April. The next day seismicity increased and acoustic signals suggested discontinuous Strombolian activity and an oscillating lava lake in the crater. Gas emissions and nighttime incandescence from the crater were observed; this activity continued through 14 April. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public was warned to stay outside of a 5-km radius around the crater and away from drainages.
Geologic summary: Glacier-clad Villarrica, one of Chile's most active volcanoes, rises above the lake and town of the same name. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide caldera formed during the late Pleistocene. A 2-km-wide caldera that formed about 3500 years ago is located at the base of the presently active, dominantly basaltic to basaltic-andesitic cone at the NW margin of the Pleistocene caldera. More than 30 scoria cones and fissure vents dot Villarrica's flanks. Plinian eruptions and pyroclastic flows that have extended up to 20 km from the volcano have been produced during the Holocene. Lava flows up to 18 km long have issued from summit and flank vents. Historical eruptions, documented since 1558, have consisted largely of mild-to-moderate explosive activity with occasional lava effusion. Glaciers cover 40 sq km of the volcano, and lahars have damaged towns on its flanks.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Elevation 1117 m
JMA reported that 15 explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 6-10 April. Incandescence from the crater was visible at night on 7 and 9 April, and inflation continued to be detected. The Alert Level remained at 3 (on a scale of 1-5). Based on JMA notices, the Tokyo VAAC reported that explosions during 8-13 April generated plumes which rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted in multiple directions. Pilots observed ash plumes that rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) and drifted E and SE during 10-11 April.
Geologic 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.
Chirpoi, Kuril Islands (Russia)
46.525°N, 150.875°E, Elevation 742 m
SVERT reported that satellite images over Snow, a volcano of Chirpoi, detected a thermal anomaly during 8-11 April. Cloud cover obscured views on other days during 7-13 April. The Aviation Color Code remained at Yellow.
Geologic summary: Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.
19.514°N, 103.62°W, Elevation 3850 m
Based on satellite images, and webcam views, Mexico City MWO notices, and wind data, the Washington VAAC reported multiple ash emissions per day from Colima during 8-10 and 13-14 April. Ash plumes rose to altitudes of 5.5-8.5 km (18,000-28,000 ft) a.s.l. and drifted in varied directions during 9-10 and 13-14 April.
Geologic 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.
Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Elevation 1335 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 8-10 and 12-14 April ash plumes from Dukono rose to altitudes of 2.4-2.7 km (8,000-9,000 ft) a.s.l. and drifted 35-75 km NE, E, and SE.
Geologic 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
INGV reported that on 12 April two explosions from the W part of Etna’s Bocca Nuova Crater were recorded within a 3-minute period beginning at 1505. Resulting ash puffs rose a few hundred meters above the crater and dispersed.
Geologic 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.
Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Elevation 1513 m
KVERT reported that during 3-10 April moderate activity at Karymsky continued. Satellite images detected ash plumes drifting 85 km SE on 3 April, and a thermal anomaly over the volcano on 9 April. The Aviation Color Code remained at Orange.7
Geologic 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.
1.697°S, 101.264°E, Elevation 3800 m
PVMBG reported that on 2 June 2013 an eruption at Kerinci from 0843 to 0848 generated an ash plume that rose 1 km above the crater. Ashfall as thick as 5 mm was reported in areas E, including Tangkil. During 1 February-13 April 2015 white plumes rose 50-150 m and drifted E and W. The Alert Level remained at 2 (on a scale of 1-4). Residents and visitors were advised not to enter an area within 3 km of the summit.
Geologic summary: The 3800-m-high Gunung Kerinci in central Sumatra forms Indonesia's highest volcano and is one of the most active in Sumatra. Kerinci is capped by an unvegetated young summit cone that was constructed NE of an older crater remnant. The volcano contains 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 of Kerinci. The massive 13 x 25 km wide volcano towers 2400-3300 m above surrounding plains and is elongated in a N-S direction. The frequently active Gunung Kerinci has been the source of numerous moderate explosive eruptions since its first recorded eruption in 1838.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Elevation 1222 m
During 8-14 April HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active with three areas of breakouts within and along the flow-field margins. The three main areas of breakouts were the 21 February breakout on the flank of Pu'u 'O'o, the 9 March breakout near the forested cone of Kahauale'a, and a relatively small forked breakout 5-6 km farther NE of Pu'u 'O'o. The circulating lava lake occasionally rose and fell in the deep pit within Halema'uma'u Crater. Gas emissions remained elevated. A lava flow from a vent at the S edge of Pu'u 'O'o began at 1700 on 7 April and remained active through 9 April.
Geologic 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 of Kilauea 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 gas-and-steam emissions at Klyuchevskoy increased at 0840 on 13 April and continued at least through 1215 on 14 April. Incandescence at the summit was indicative of renewed Strombolian activity. The Aviation Color Code was raised to Yellow.
Geologic 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.
19.023°N, 98.622°W, Elevation 5426 m
CENAPRED reported that after a series of explosions ended at 1200 on 7 April the seismic network at Popocatépetl recorded 78 low-intensity emissions through 1100 on 8 April; gas-and-steam plumes containing small amounts of ash drifted SE. Also during this period 93 explosions occurred, and 12 minutes of harmonic tremor were detected on 8 April. During 8-14 April the seismic network recorded 20-112 gas, steam, and ash emissions, and nighttime crater incandescence was often noted. On 9 and 10 April the network detected 41 and 120 minutes of harmonic tremor, respectively. During an overflight on 10 April scientists confirmed that a lava dome was emplaced in the bottom of the crater between 24 March and 4 April. The lava dome was at least 250 m in diameter and 30 m thick. The surface of the dome had concentric fractures and the central part was collapsed from deflation. Explosions were detected during 13-14 April. The Alert Level remained at Yellow, Phase Two.
Geologic summary: Volcán Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5426 m 70 km SE of Mexico City to form North America's 2nd-highest volcano. The glacier-clad stratovolcano contains a steep-walled, 400 x 600 m wide crater. The generally symmetrical volcano is modified by the sharp-peaked Ventorrillo on the NW, a remnant of an earlier volcano. At least three previous major cones were destroyed by gravitational failure during the Pleistocene, producing massive debris-avalanche deposits covering broad areas to the south. The modern volcano was constructed south of the late-Pleistocene to Holocene El Fraile cone. Three major plinian eruptions, the most recent of which took place about 800 CE, have occurred from Popocatépetl since the mid Holocene, accompanied by pyroclastic flows and voluminous lahars that swept basins below the volcano. Frequent historical eruptions, first recorded in Aztec codices, have occurred since precolumbian time.
San Miguel, El Salvador
13.434°N, 88.269°W, Elevation 2130 m
SNET reported that at 1515 on 11 April a small explosion at San Miguel generated a gas-and-ash plume that rose 800 m and quickly dissipated to the SW. Minor ashfall (1 mm thick) was reported WSW of the crater, in La Piedra, Moritas, and San Jorge.
Geologic summary: The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit of the 2130-m-high volcano rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit of the towering volcano, which is also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the north, NE, and SE sides. The SE-flank lava flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.
Sheveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Elevation 3283 m
KVERT reported that during 3-10 April lava-dome extrusion onto Sheveluch’s N flank was accompanied by incandescence, hot block avalanches, and fumarolicactivity. Strong explosions on 3 and 7 April generated ash plumes that rose to altitudes of 9 and 12 km (32,800 ft) a.s.l., and drifted 100 km SE and more than 450 km NE, respectively. A daily thermal anomaly was also visible in satellite images. The Aviation Color Code remained at Orange.
Geologic 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.
Shishaldin, Fox Islands (USA)
54.756°N, 163.97°W, Elevation 2857 m
AVO reported that seismicity at Shishaldin continued to be elevated over background levels during 8-14 April. They interpreted those data as indicating that low-level eruptive activity confined to the summit crater likely continued. Cloud cover frequently prevented satellite and webcam observations. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Geologic 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.
Slamet, Central Java (Indonesia)
7.242°S, 109.208°E, Elevation 3428 m
PVMBG reported that during 1 February-10 April dense white plumes rose 50-800 m above Slamet's crater. Seismicity consisted of emission signals and tremor; emission signals started to increase on 18 February and periods of continuous tremor were recorded during 21-22 and 28-29 March. RSAM values fluctuated but rose overall. The Alert Level remained at 2 (on a scale of 1-4). Residents and tourists were warned to not approach the crater within a radius of 2 km.
Geologic summary: Slamet, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. It is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper E flank on the younger edifice fed a lava flow that extends 6 km E. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time. Historical eruptions, recorded since the 18th century, have originated from a 150-m-deep, 450-m-wide, steep-walled crater at the western part of the summit and have consisted of explosive eruptions generally lasting a few days to a few weeks.
Suwanosejima, Ryukyu Islands (Japan)
29.638°N, 129.714°E, Elevation 796 m
Based on JMA notices, the Tokyo VAAC reported that an eruption at Suwanose-jima on 13 April generated a plume that rose to an altitude of 2.1 km (7,000 ft)a.s.l. and drifted N.7
Geologic 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 persons live on the island.
16.355°S, 70.903°W, Elevation 5672 m
INGEMMET's Observatorio Vulcanológico (OVI) reported that after a decline in activity at Ubinas during the previous five months two phreatic explosions were detected on 8 April. The explosions occurred at 0424 and 0550, generated ash-and-gas plumes that rose 2-2.5 km above the crater and drifted SE. According to Observatorio Volcanológico del Sur (OVS) snowmelt during 12-13 April led to large lahars that descended the S flank. A report on 13 April noted that large volumes of ash continued to be emitted during the previous 48 hours.
Geologic summary: A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Perú. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.
Zhupanovsky, Eastern Kamchatka (Russia)
53.589°N, 159.15°E, Elevation 2899 m
KVERT reported that a moderate explosive eruption at Zhupanovsky continued during 3-10 April. Satellite images detected ash plumes drifting 25 km SE on 3 April and a thermal anomaly over the volcano on 9 April. The Aviation Color Code remained at Orange.
Geologic summary: The Zhupanovsky volcanic massif consists of four overlapping stratovolcanoes along a WNW-trending ridge. The elongated volcanic complex was constructed within a Pliocene-early Pleistocene caldera whose rim is exposed only on the eastern side. Three of the stratovolcanoes were built during the Pleistocene, the fourth is Holocene in age and was the source of all of Zhupanovsky's historical eruptions. An early Holocene stage of frequent moderate and weak eruptions from 7000 to 5000 years before present (BP) was succeeded by a period of infrequent larger eruptions that produced pyroclastic flows. The last major eruption took place about 800-900 years BP. Historical eruptions have consisted of relatively minor explosions from the third cone.
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