New activity/unrest was reported for 6 volcanoes between April 19 and 25, 2017. During the same period, ongoing activity was reported for 13 volcanoes.
New activity/unrest: Ibu, Halmahera (Indonesia) | Kambalny, Southern Kamchatka (Russia) | Langila, New Britain (Papua New Guinea) | Manam, Papua New Guinea | Nishinoshima, Japan | Poas, Costa Rica.
Ongoing activity: Bagana, Bougainville (Papua New Guinea) | Bezymianny, Central Kamchatka (Russia) | Bogoslof, Fox Islands (USA) | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Nevados de Chillan, Chile | Sabancaya, Peru | San Miguel, El Salvador | Sheveluch, Central Kamchatka (Russia), Sinabung, Indonesia.
Ibu, Halmahera (Indonesia)
1.488°N, 127.63°E, Elevation 1325 m
Based on PVMBG observations the Darwin VAAC reported that during 19-21 April ash plumes from Ibu rose 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted E and N.
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.
Kambalny, Southern Kamchatka (Russia)
51.306°N, 156.875°E, Elevation 2116 m
KVERT reported that moderate activity at Kambalny continued during 15-21 April. Observers in the South Kamchatka Sanctuary noted minor ashfall in the Kurilskoe Lake area on 19 April. The Aviation Color Code remained at Orange.
Geological summary: The southernmost major stratovolcano on the Kamchatka peninsula, 2116-m-high Kambalny has a summit crater that is breached to the SE. Five Holocene cinder cones on the W and SE flanks have produced fresh-looking lava flows. Beginning about 6300 radiocarbon years ago, a series of major collapses of the edifice produced at least three debris-avalanche deposits. The last major eruption took place about 600 years ago, although younger tephra layers have been found, and an eruption was reported in 1767. Active fumarolic areas are found on the flanks of the volcano, which is located south of the massive Pauzhetka volcano-tectonic depression.
Langila, New Britain (Papua New Guinea)
5.525°S, 148.42°E, Elevation 1330 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 23-25 April ash plumes from Langila rose to an altitude of 2.1 km (7,000 ft) a.s.l., and drifted S and 55 km SE.
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.
Manam, Papua New Guinea
4.08°S, 145.037°E, Elevation 1807 m
RVO reported that activity at Manam decreased on 18 April and continued at low levels through 21 April. Roaring noises came from both Main and Southern craters. Both craters were incandescent, but only Southern Crater ejected incandescent tephra, which became intense during 0900-1100 on 20 April. Pale gray-to-brown plumes with a minor amounts of ash rose from both craters and drifted SE. RSAM values were about 75-150 units, but between about midnight and 0100 on 22 April they began to rise. RSAM values were 600 at 0500, and then they fluctuated between 400 and 1,400 units at least through 1400, the time of the report posting. According to a news article from 25 April the Alert Level was raised to Stage 3, and an official on the island noted that women and children have begun to be evacuated to Bogia on the mainland.
Geological 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.
27.247°N, 140.874°E, Elevation 25 m
Satellite images of Nishinoshima acquired on 19 April and processed by NASA's Earth Observatory showed an area of hot lava in the crater. According to a news article, observers aboard a plane passing the volcano on 21 April noted intense activity in the crater. Bombs were ejected as high as 100 m above the crater and incandescent rocks rolled down the flanks, reaching the sea. The report noted brown plumes rising from the crater and lava effusing from an area near the top of the vent.
Geological summary: The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previous exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since. The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m of the sea surface 9 km SSE.
Poas, Costa Rica
10.2°N, 84.233°W, Elevation 2708 m
OVSICORI-UNA reported that on 20 April a dense water vapor plume rose from a vent in the newly-forming pyroclastic cone at the site of the old dome in the hot lake at Poás. Gas flux increased from 1,000 tons/day (t/d) on 13 April to 2,500 t/d on 20 April. During 20-22 April Strombolian activity ejected tephra that fell around the vent within a 300-m radius. Gas-and-ash plumes rose 200 m above the vent. The Red Cross of Grecia reported ashfall in Alajuela, Fraijanes, San Miguel, Carbonal, Cajón, San Francisco, San Roque, and San Juan Norte de Poás. Events at 1316 and 1603 on 22 April produced plumes of unknown height. Several more eruptive events were recorded that day; an event at 2212 was very intense, ejecting bombs large distances. An event at 1215 on 23 April generated a plume of unknown height.
Geological summary: The broad, well-vegetated edifice of Poás, one of the most active volcanoes of Costa Rica, contains three craters along a N-S line. The frequently visited multi-hued summit crater lakes of the basaltic-to-dacitic volcano, which is one of Costa Rica's most prominent natural landmarks, are easily accessible by vehicle from the nearby capital city of San José. A N-S-trending fissure cutting the 2708-m-high complex stratovolcano extends to the lower northern flank, where it has produced the Congo stratovolcano and several lake-filled maars. The southernmost of the two summit crater lakes, Botos, is cold and clear and last erupted about 7500 years ago. The more prominent geothermally heated northern lake, Laguna Caliente, is one of the world's most acidic natural lakes, with a pH of near zero. It has been the site of frequent phreatic and phreatomagmatic eruptions since the first historical eruption was reported in 1828. Eruptions often include geyser-like ejections of crater-lake water.
Bagana, Bougainville (Papua New Guinea)
6.137°S, 155.196°E, Elevation 1855 m
Based on analyses of satellite imagery and model data, the Darwin VAAC reported that during 16-17 April ash plumes from Bagana rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted N, SE, and S. Plumes drifted 55-85 km during 19 and 23-24 April.
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.
Bezymianny, Central Kamchatka (Russia)
55.972°N, 160.595°E, Elevation 2882 m
KVERT reported that during 14-21 April lava continued to advance down the NW flank of Bezymianny's lava dome. A thermal anomaly was identified in satellite images during 14-17 April. The Aviation Color Code remained at Orange.
Geological summary: Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.
Bogoslof, Fox Islands (USA)
53.93°N, 168.03°W, Elevation 150 m
On 19 April AVO noted that no new volcanic activity at Bogoslof had been detected in satellite, seismic, or infrasound data since a short-lived increase in seismicity on 15 April; AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory.
Geological summary: Bogoslof is the emergent summit of a submarine volcano that lies 40 km north of the main Aleutian arc. It rises 1500 m above the Bering Sea floor. Repeated construction and destruction of lava domes at different locations during historical time has greatly modified the appearance of this "Jack-in-the-Box" volcano and has introduced a confusing nomenclature applied during frequent visits of exploring expeditions. The present triangular-shaped, 0.75 x 2 km island consists of remnants of lava domes emplaced from 1796 to 1992. Castle Rock (Old Bogoslof) is a steep-sided pinnacle that is a remnant of a spine from the 1796 eruption. Fire Island (New Bogoslof), a small island located about 600 m NW of Bogoslof Island, is a remnant of a lava dome that was formed in 1883.
Cleveland, Chuginadak Island (USA)
52.825°N, 169.944°W, Elevation 1730 m
AVO reported that recent satellite images of Cleveland revealed that a lava dome has been extruded in the summit crater, with growth likely beginning after the last explosion on 31 March. The Aviation Color Code was raised to Orange and the Volcano Alert Level was raised to Watch.
Slightly elevated surface temperatures were identified in satellite images over the past couple of weeks. The new dome was first visible in images on 15 April, with the presence of a small (less than 10 m diameter) mound deep in the crater. By 23 April this mound had grown to 45 m in diameter. Dome growth had occurred with no detectable seismicity.
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, Elevation 1229 m
Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 19-25 April ash plumes from Dukono rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted NE, E, and SE.
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
KVERT reported that on 14, 16, and 19 April several explosions at Ebeko were observed by residents of Severo-Kurilsk (Paramushir Island) about 7 km E. Ash plumes rose as high as 3.2 km (10,500 ft) a.s.l. Minor amounts of ash fell in Severo-Kurilsk on 18 April. 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, Elevation 1222 m
During 19-25 April 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, from a vent high on the NE flank of the cone, and from a small lava pond in a pit on the W side of the crater. The 61G lava flow, originating from a vent on Pu'u 'O'o Crater's E flank, continued to enter the ocean at Kamokuna. A growing lava delta is building where the lava enters the water. Surface lava flows were active above the pali.
Geological summary: Kilauea volcano, which overlaps the east flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island.
Klyuchevskoy, Central Kamchatka (Russia)
56.056°N, 160.642°E, Elevation 4754 m
KVERT reported that a weak thermal anomaly was detected over Klyuchevskoy during 14-17 and 23 April. A steam-and-gas plume that rose to 5 km (16,400 ft) a.s.l. and drifted 125 km SW on 23 April contained some ash, prompting KVERT to raise the Aviation Color Code to Orange. On 24 April satellite images showed an ash plume drifting 72 km SW at an altitude of 7 km (23,000 ft) a.s.l. On 25 April KVERT noted that activity had significantly decreased and only steam-and-gas emissions were observed. The Aviation Color Code was lowered to Yellow. On 25 April ash was again present in a plume; KVERT raised the Aviation Color Code to Orange. The plume rose 3-4 km (9,800-13,100 ft) a.s.l. and drifted 60 km SW.
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.
Nevados de Chillan, Chile
36.863°S, 71.377°W, Elevation 3212 m
The Buenos Aires VAAC reported that on 21 April a webcam recorded a steam, gas, and ash puff rising from Nevados de Chillán to 4 km (13,000 ft) a.s.l. and dispersing rapidly near the summit.
Geological summary: The compound volcano of Nevados de Chillán is one of the most active of the Central Andes. Three late-Pleistocene to Holocene stratovolcanoes were constructed along a NNW-SSE line within three nested Pleistocene calderas, which produced ignimbrite sheets extending more than 100 km into the Central Depression of Chile. The largest stratovolcano, dominantly andesitic, Cerro Blanco (Volcán Nevado), is located at the NW end of the group. Volcán Viejo (Volcán Chillán), which was the main active vent during the 17th-19th centuries, occupies the SE end. The new Volcán Nuevo lava-dome complex formed between 1906 and 1945 between the two volcanoes and grew to exceed Volcán Viejo in elevation. The Volcán Arrau dome complex was constructed SE of Volcán Nuevo between 1973 and 1986 and eventually exceeded its height.
15.78°S, 71.85°W, Elevation 5967 m
Based on webcam images, satellite views, and seismic data the Buenos Aires VAAC reported sporadic gas-and-ash puffs from Sabancaya during 18-25 April, sometimes rising as high as 8.2 km (25,000 ft) a.s.l.; clouds sometimes hindered observations of the volcano.
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.
San Miguel, El Salvador
13.434°N, 88.269°W, Elevation 2130 m
In a special report from 17 April, SNET reported an increase in seismicity and gas emissions from San Miguel in recent days. Earlier that day during 0620-0630 RSAM values spiked to 356, an increase over normal values around 50. During 18-21 and 23-24 April RSAM values fluctuated between 80 and over 300.
Geological 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, 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 15-21 April lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a thermal anomaly over the dome during 13-17 April, and an ash plume that drifted 95 km E on 15 April. 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 cu km volcano is one of Kamchatka's largest and most active volcanic structures. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes dot its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large horseshoe-shaped caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. At least 60 large eruptions have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.
3.17°N, 98.392°E, Elevation 2460 m
Based on PVMBG observations, satellite images, and wind data, the Darwin VAAC reported that during 20-22 and 24 April ash plumes from Sinabung rose to altitudes of 3.3-4.3 km (11,000-14,000 ft) a.s.l. and drifted SW and E.
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.
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