New activity/unrest was observed at 5 volcanoes from July 1 – 7, 2015. During the same period, ongoing activity was observed at 18 volcanoes.
New activity/unrest: Fuego, Guatemala | Hakoneyama, Honshu (Japan) | Raung, Eastern Java (Indonesia) | Sangeang Api, Indonesia | Sirung, Pantar Island (Indonesia)
Ongoing activity: Aira, Kyushu (Japan) | Batu Tara, Komba Island (Indonesia) | Concepcion, Nicaragua | Dukono, Halmahera (Indonesia) | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Manam, Papua New Guinea | Ontakesan, Honshu (Japan) | Popocatepetl, Mexico | Reventador, Ecuador | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Sinabung, Indonesia | Soputan, Sulawesi (Indonesia) | Tungurahua, Ecuador | Ubinas, Peru | Zhupanovsky, Eastern Kamchatka (Russia)
14.473°N, 90.88°W, Summit elev. 3763 m
Based on INSIVUMEH notices, CONRED reported that for a 30-hour period during 30 June-1 July activity at Fuego was at a high level, characterized by explosions, high-temperature pyroclastic flows (that began on 1 July), and ashfall. Ash plumes rose 4.8 km above the crater and drifted 25 km W and NW, producing ashfall in 22 local communities. The majority of material deposited by pyroclastic flows was in the Las Lajas drainage. Activity decreased later that day. During 4-6 July, INSIVUMEH reported that explosions produced ash plumes that rose as high as 800 m above the crater and drifted 8-10 km SW and W. Incandescent material was ejected 100 m high, and avalanches descended the Santa Teresa and other nearby drainages.
Geologic summary: Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at Acatenango. In contrast to the mostly andesitic Acatenango, eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.
Hakoneyama, Honshu (Japan)
35.233°N, 139.021°E, Summit elev. 1438 m
According to a news article a drone that surveyed the Owakudani hot spring district at Hakoneyama recorded damage to three hot spring supply facilities; an exclusion zone for visitors was in effect due to increased seismic activity and an Alert Level raise to 2 (on a 5-level scale) on 6 May. At 1230 on 30 June a small-scale eruption occurred and the Alert Level was raised to 3. On 1 July a news article noted another small-scale eruption (occurring between 0400 and 0500), and JMA reported that ash deposits were visible with the webcam. During fieldwork on 2 July, scientists confirmed new fumaroles at Owakudani that were vigorously emitting white plumes; the new fumaroles had formed during 29-30 June. White fumarolic plumes continued to be emitted through 5 July.
Geologic summary: Hakoneyama volcano is truncated by two overlapping calderas, the largest of which is 10 x 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000-60,000 years ago. Scenic Lake Ashi lies between the SW caldera wall and a half dozen post-caldera lava domes that were constructed along a SW-NE trend cutting through the center of the calderas. Dome growth occurred progressively to the south, and the largest and youngest of these, Kamiyama, forms the high point of Hakoneyama. The calderas are breached to the east by the Hayakawa canyon. A phreatic explosion about 3000 years ago was followed by collapse of the NW side of Kamiyama, damming the Hayakawa valley and creating Lake Ashi. The latest magmatic eruptive activity about 2900 years ago produced a pyroclastic flow and a lava dome in the explosion crater, although phreatic eruptions took place as recently as the 12-13th centuries CE. Seismic swarms have occurred during the 20th century. Lake Ashi, along with major thermal areas in the caldera, forms a popular resort area SW of Tokyo.
Raung, Eastern Java (Indonesia)
8.125°S, 114.042°E, Summit elev. 3332 m
Based on notices from the Ujung Padang MWO and PVMBG, satellite images, and pilot observations, the Darwin VAAC reported that during 1 and 3-7 July ash plumes from Raung rose to altitudes of 3.7-6.1 km (12,000-20,000 ft) a.s.l. and drifted 25-110 km E, ESE, and SE. According to news articles, flights in and out of an airport in Bali were cancelled due to ash emissions during 3-4 July. On 5 July BNPB reported that roaring was heard from continuous explosions and Strombolian activity at Raung. Dense white-and-gray plumes rose as high as 400 m and drifted SE. The Alert Level remained at 3 (on a scale of 1-4), and the public was reminded not to approach the crater within a 3-km radius.
Geologic summary: Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The 3332-m-high, unvegetated summit of Gunung Raung is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the west flank produced a large debris avalanche that traveled 79 km from the volcano, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and west, respectively.
Sangeang Api, Indonesia
8.2°S, 119.07°E, Summit elev. 1949 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 7 July an ash plume from Sangeang Api rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted over 35 km E.
Geologic 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-
Sirung, Pantar Island (Indonesia)
8.508°S, 124.13°E, Summit elev. 862 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 7 July an ash plume from Sirung rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted 85 km SW.
Geologic summary: Sirung volcano is located at the NE end of a 14-km-long line of volcanic centers that form a peninsula at the southern end of Pantar Island. The low, 862-m-high volcano is truncated by a 2-km-wide caldera whose floor often contains one or more small lakes. Much of the volcano is constructed of basaltic lava flows, and the Gunung Sirung lava dome forms the high point on the caldera's western rim. A number of phreatic eruptions have occurred from vents within the caldera during the 20th century. Forested Gunung Topaki, the 1390-m high point of the volcanic chain, lies at the SW end and contains a symmetrical summit crater.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported 14 explosions during 29 June-6 July from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was occasionally visible. The Alert Level remained at 3 (on a 5-level scale).
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.
Batu Tara, Komba Island (Indonesia)
7.792°S, 123.579°E, Summit elev. 748 m
During 30 June-4 July observers at Batu Tara noted Strombolian eruptions of varying intensity at intervals ranging between 10 and 50 minutes. Three pyroclastic flows traveled as far as 200 m over the sea during a 16-hour period of elevated activity between 2 and 3 July.
Geologic summary: The small isolated island of Batu Tara in the Flores Sea about 50 km N of Lembata (fomerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption, during 1847-52, produced explosions and a lava flow.
11.538°N, 85.622°W, Summit elev. 1700 m
INETER reported that gas explosions continued to be detected at Concepción; by 7 July a total of 2,417 explosions, 117 since 30 June, had been detected by the network since activity increased (date not specified).
Geologic summary: Volcán Concepción is one of Nicaragua's highest and most active volcanoes. The symmetrical basaltic-to-dacitic stratovolcano forms the NW half of the dumbbell-shaped island of Ometepe in Lake Nicaragua and is connected to neighboring Madera volcano by a narrow isthmus. A steep-walled summit crater is 250 m deep and has a higher western rim. N-S-trending fractures on the flanks of the volcano have produced chains of spatter cones, cinder cones, lava domes, and maars located on the NW, NE, SE, and southern sides extending in some cases down to Lake Nicaragua. Concepción was constructed above a basement of lake sediments, and the modern cone grew above a largely buried caldera, a small remnant of which forms a break in slope about halfway up the north flank. Frequent explosive eruptions during the past half century have increased the height of the summit significantly above that shown on current topographic maps and have kept the upper part of the volcano unvegetated.
Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Summit elev. 1335 m
PVMBG reported that during May-June white-and-gray plumes rose as high as 1.2 km above Dukono's Malupang Warirang Crater rim and were accompanied by rumbling and roaring. A powerful explosion on 23 May was followed by minor ashfall in areas to the E. During 1-5 July white-and-gray plumes rose as high as 600 m; minor ashfall was reported in northern areas on 1 July. The Alert Level remained at 2 (on a scale of 1-4). Residents and tourists were advised not to approach the crater within a radius of 2 km.
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 31 June-3 July ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 25-165 km NE. On 7 July ash plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 45 km NE.
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.
Karymsky, Eastern Kamchatka (Russia)
54.049°N, 159.443°E, Summit elev. 1513 m
KVERT reported that explosive activity at Karymsky likely continued during 26 June-3 July; a small ash cloud above the volcano was visible in satellite images on 1 July. The Aviation Color Code remained at Orange.
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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m
HVO reported that seismicity beneath Kilauea's summit, upper East Rift Zone, and Southwest Rift Zone was at background levels during 1-7 July. The lava lake continued to be active in the deep pit within the Overlook vent, vigorously spattering. On 1 July part of the rim and wall of Overlook crater collapsed into the lava lake, starting at about 1430, producing an ashy plume, rapid oscillation of the lava lake, and intense spattering in the lake at the impact site. The June 27th NE-trending lava flow continued to be active with surface flows within 8 km NE of Pu'u 'O'o Crater. Webcams recorded multiple incandescent outgassing vents within Pu'u 'O'o.
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.
Manam, Papua New Guinea
4.08°S, 145.037°E, Summit elev. 1807 m
Based on observations of satellite imagery and wind data analyses, the Darwin VAAC reported that during 1-2 July ash plumes from Manam rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted 45-130 km E and SE.
Geologic summary: The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Ontakesan, Honshu (Japan)
35.893°N, 137.48°E, Summit elev. 3067 m
JMA reported that activity at Ontakesan continued to decline during 26 June-3 July, although the volcano continued to be seismically active and emit white plumes to less than 1 km high. The Alert Level was lowered to 2 (on a scale of 1-5).
Geologic summary: The massive Ontakesan stratovolcano, the second highest volcano in Japan, lies at the southern end of the Northern Japan Alps. Ascending this volcano is one of the major objects of religious pilgrimage in central Japan. It is constructed within a largely buried 4 x 5 km caldera and occupies the southern end of the Norikura volcanic zone, which extends northward to Yakedake volcano. The older volcanic complex consisted of at least four major stratovolcanoes constructed from about 680,000 to about 420,000 years ago, after which Ontakesan was inactive for more than 300,000 years. The broad, elongated summit of the younger edifice is cut by a series of small explosion craters along a NNE-trending line. Several phreatic eruptions post-date the roughly 7300-year-old Akahoya tephra from Kikai caldera. The first historical eruption took place in 1979 from fissures near the summit. A non-eruptive landslide in 1984 produced a debris avalanche and lahar that swept down valleys south and east of the volcano. Very minor phreatic activity caused a dusting of ash near the summit in 1991 and 2007. A significant phreatic explosion in September 2014, when a large number of hikers were at or near the summit, resulted in many fatalities.
19.023°N, 98.622°W, Summit elev. 5426 m
CENAPRED reported that during 1-7 July the seismic network at Popocatépetl recorded 18-118 daily emissions consisting of water vapor, gas, with ash seen on 7 July only; cloud cover often prevented visual observations. Gas-and-steam plumes were observed daily, and variable nighttime crater incandescence was observed. An explosion was detected at 1024 on 1 July, and 14 were detected during 5-7 July. 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.
0.077°S, 77.656°W, Summit elev. 3562 m
During 1-7 July IG reported a high level of seismic activity including explosions, tremor, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador; cloud cover sometimes prevented visual observations. Incandescent material that traveled more than 1 km down the SE flank was visible during 1-2 and 6 July in thermal images. Ash emissions were visible on 2 July, and a steam-and-ash plume that rose 2 km and drifted SW was visible the next day. A minor ash emission rose less than 500 m and drifted W on 6 July.
Geologic summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.
Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m
INSIVUMEH reported that an explosion at 0436 on 5 July from Caliente cone, part of Santa María's Santiaguito lava-dome complex, generated an ash plume that rose 500 m and drifted SW. Explosions during 5-6 July produced ash plumes that rose 800 m and drifted W, causing ashfall in the Palajunoj area. Avalanches from lava-flow fronts descended the flanks.
Geologic 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, Summit elev. 3283 m
KVERT reported that during 26 June-3 July lava-dome extrusion onto Sheveluch’s N flank was accompanied by fumarolic activity. Satellite images showed a thermal anomaly over the volcano during 25-28 and 30 June; weather clouds obscured the volcano on the other days. 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, Summit elev. 2857 m
AVO reported that seismicity at Shishaldin continued to be elevated over background levels 1-7 July indicating that low-level eruptive activity confined to the summit crater likely continued. Although cloud cover often prevented visual observations, webcam images showed periodic steaming, and ash at the summit during 2-3 July. Elevated surface temperatures at the summit were detected in satellite images on 3 and 7 July. 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.
3.17°N, 98.392°E, Summit elev. 2460 m
Based on reports from PVMBG, the Darwin VAAC reported that on 1 July an ash plume rose 2 km above Sinabung’s summit crater and drifted E. The next day an ash plume rose 1.6 km above the crater.
Geologic 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.
Soputan, Sulawesi (Indonesia)
1.108°N, 124.73°E, Summit elev. 1784 m
PVMBG reported that during June-3 July white plumes were observed rising as high as 750 m above Soputan even though inclement weather sometimes obscured crater views. Seismicity during the previous three months had declined (specifically shallow volcanic earthquakes, volcanic earthquakes, and signals indicating emissions and avalanches) but remained higher than levels recorded prior to the elevated activity which lead to the Alert Level increase on 26 December 2014. Low-frequency harmonic tremor was occasionally detected. The Alert Level was lowered to 2 (on a scale of 1-4). Residents and tourists were advised not to approach the craters within a radius of 4 km, or 6.5 km on the WSW flank.
Geologic summary: The small Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Sempu volcano. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.
1.467°S, 78.442°W, Summit elev. 5023 m
IG reported moderate seismic activity at Tungurahua during 31 June-7 July, characterized by long-period events, minor instances of tremor, and one explosion. Cloud cover often prevented visual observations. On 31 June a vapor plume rose 500 m and drifted NW. Small amounts of ash fell in Choglontus (13 km WSW) and El Manzano (8 km SW), and roaring was reported. A steam emission rose 300 m on 3 July, and minor ashfall was again reported in Choglontus. An explosion produced a steam-and-ash plume that rose 1 km and drifted NW. A small pyroclastic flow occurred near the crater. Ashfall was reported in Choglontus. On 6 July minor ashfall was reported in El Manzano and a small explosion was recorded at 0554. A lahar descended the Achupashal drainage causing a road closure near Pájaros-Penipe.
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.
16.355°S, 70.903°W, Summit elev. 5672 m
Instituto Geofísico del Perú (IGP) Observatorio Volcanológico del Sur (OVS) reported that during 30 June-6 July volcano-tectonic earthquakes decreased and the rate of long-period events remained steady as compared to the previous week. The number of hybrid events slightly increased. Explosions were observed, and ash emissions rose as high as 1.6 km above the crater base and drifted NE, E, and SE.
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, Summit elev. 2899 m
KVERT reported that explosive activity at Zhupanovsky probably continued during 26-3 July; weather clouds obscured views of the volcano. 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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