Active volcanoes in the world: June 13 - 20, 2017

Active volcanoes in the world: June 13 - 20, 2017

New activity/unrest was reported for 5 volcanoes between June 14 and 20, 2017. During the same period, ongoing activity was reported for 15 volcanoes.

New activity/unrest: Bogoslof, Fox Islands (USA) | Karymsky, Eastern Kamchatka (Russia) | Pavlof, United States | Rincon de la Vieja, Costa Rica | Sheveluch, Central Kamchatka (Russia).

Ongoing activity: Aira, Kyushu (Japan) | Bagana, Bougainville (Papua New Guinea) | Bezymianny, Central Kamchatka (Russia) | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Ibu, Halmahera (Indonesia) | Kilauea, Hawaiian Islands (USA) | Klyuchevskoy, Central Kamchatka (Russia) | Langila, New Britain (Papua New Guinea) | Poas, Costa Rica | Sabancaya, Peru | Sinabung, Indonesia | Turrialba, Costa Rica.

New activity/unrest

Bogoslof, Fox Islands (USA)

53.93°N, 168.03°W, Summit elev. 150 m

AVO reported that elevated surface temperatures and a small steam emission at Bogoslof were identified in satellite images during 13-14 June. Weakly elevated surface temperatures were detected on 16 June, and a 13-km-long steam plume was visible on 18 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geologic 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.

Karymsky, Eastern Kamchatka (Russia)

54.049°N, 159.443°E, Summit elev. 1513 m

KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 10-12 and 14-15 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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.

Pavlof, United States

55.417°N, 161.894°W, Summit elev. 2493 m

AVO reported that seismicity at Pavlof had declined since the small increase on 7 June, and no unusual activity was observed in seismic or infrasound data through 20 June. Minor steam emissions occasionally rose from the summit crater. Satellite images showed an approximately 55 km-long steam plume drifting W on 14 June, and a thermal anomaly during 15-16 and 20 June. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Geologic summary: The most active volcano of the Aleutian arc, Pavlof is a 2519-m-high Holocene stratovolcano that was constructed along a line of vents extending NE from the Emmons Lake caldera. Pavlof and its twin volcano to the NE, 2142-m-high Pavlof Sister, form a dramatic pair of symmetrical, glacier-covered stratovolcanoes that tower above Pavlof and Volcano bays. A third cone, Little Pavlof, is a smaller volcano on the SW flank of Pavlof volcano, near the rim of Emmons Lake caldera. Unlike Pavlof Sister, Pavlof has been frequently active in historical time, typically producing Strombolian to Vulcanian explosive eruptions from the summit vents and occasional lava flows. The active vents lie near the summit on the north and east sides. The largest historical eruption took place in 1911, at the end of a 5-year-long eruptive episode, when a fissure opened on the N flank, ejecting large blocks and issuing lava flows.

Rincon de la Vieja, Costa Rica

10.83°N, 85.324°W, Summit elev. 1916 m

OVSICORI-UNA reported that on 15 June a diffuse plume of mainly water vapor rose 50 m above Rincón de la Vieja's crater rim. A small hydrothermal explosion from the crater with the highly acidic lake was detected around noon on 18 June. In a report posted the next day OVSICORI-UNA noted that seismicity was characterized by low-frequency events, volcano-tectonic events, and tremor with intensifying amplitude; the seismic patterns were similar to those that preceded the phreatomagmatic events on 23 May and 11 June, though the recent seismicity was not as energetic.

Geologic summary: Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge that was constructed within the 15-km-wide early Pleistocene Guachipelín caldera, whose rim is exposed on the south side. Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 cu km and contains at least nine major eruptive centers. Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of 1916-m-high Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5-km-wide caldera and has a 500-m-wide crater. A plinian eruption producing the 0.25 cu km Río Blanca tephra about 3500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16th century, have been from the prominent crater containing a 500-m-wide acid lake (known as the Active Crater) located ENE of Von Seebach crater.

Sheveluch, Central Kamchatka (Russia)

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

KVERT reported that during 10-13 June explosions at Sheveluch produced ash plumes that rose as high as 8 km (26,200 ft) a.s.l. and drifted 1,500 km SE and NW. At 0425 on 15 June powerful explosions generated ash plumes that rose as high as 12 km (39,400 ft) a.s.l. The Aviation Color Code was raised to Red (the highest level on a four-color scale), and then back down to Orange at the end of the day. Ash plumes drifted 1,000 km NE and SW during 15-16 June. Ash fell in Klyuchi (50 km SW), Maiskoe, Kozyrevsk (115 km SW), and Atlasovo (160 km SW).

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.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that an event at Showa Crater (at Aira Caldera’s Sakurajima volcano) at 1208 on 15 June generated an ash plume that rose 2.8 km above the crater rim. 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.

Bagana, Bougainville (Papua New Guinea)

6.137°S, 155.196°E, Summit elev. 1855 m

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 14 June an ash plume from Bagana drifted W at an altitude of 2.1 km (7,000 ft) a.s.l. No ash was identified in inages later that day.

Geologic 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, Summit elev. 2882 m

On 15 June KVERT reported that the temperature of a thermal anomaly identified in satellite images had increased, and that the webcam recorded a gas-and-steam plume rising above Bezymianny to 4 km (13,100 ft) a.s.l. and drifted SSE. Hot avalanches of material originated from the lava dome. An explosive event began at 1653 on 16 June, producing an ash cloud 28 x 25 km in size that drifted NE. The Aviation Color Code was raised to Red (the highest level on a four-color scale), but lowered back down to Orange about 5 hours later. At 2110 the ash cloud was 212 x 115 km in size and drifting E; the leading edge of the cloud was about 245 km E.

Geologic 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.

Cleveland, Chuginadak Island (USA)

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

AVO reported that no unusual activity at Cleveland had been detected in seismic or infrasound data during 14-20 June. Minor steaming from the summit was recorded by a webcam during 17-18 June, and slightly elevated surface temperatures were identified in a satellite image acquired on 19 and 20 June. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

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

Dukono, Halmahera (Indonesia)

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

Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 14-20 June ash plumes from Dukono rose to altitudes of 1.5-3 km (5,000-10,000 ft) a.s.l. and drifted in multiple directions.

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.

Ebeko, Paramushir Island (Russia)

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

Based on observations by residents of Severo-Kurilsk (Paramushir Island) about 7 km E of Ebeko, KVERT reported that explosive activity continued at the volcano during 9-16 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Geologic 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.

Fuego, Guatemala

14.473°N, 90.88°W, Summit elev. 3763 m

INSIVUMEH reported that during 13-14 June explosions at Fuego generated shock waves detected within 10 km, and block avalanches descended the Ceniza (SSW), Taniluyá (SW), Santa Teresa (SW), and Trinidad (S) ravines. On 18 June heavy rain triggered a 20-m-wide, 1.5-m-deep lahar that traveled down the El Jute (SE) ravine, carrying tree trunks and blocks as large a 2 m in diameter. Explosions during 18-20 June produced ash plumes that rose as high as 950 m above the crater and drifted 8-12 km S, SW, and W. Ashfall was noted in areas downwind including Morelia (9 km SW), Santa Sofía (12 km SW), Finca Palo Verde, El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), and Panimaché I and II (8 km SW). Incandescent material was ejected 100-200 m above the crater rim, and caused avalanches of material that traveled into the Ceniza, Taniluyá, Trinidad, and Santa Teresa 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.

Ibu, Halmahera (Indonesia)

1.488°N, 127.63°E, Summit elev. 1325 m

Based on PVMBG observations, satellite images, and wind data, the Darwin VAAC reported that during 14 and 17-19 June ash plumes from Ibu rose 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted S, SW, W, and N.

Geologic 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.

Kilauea, Hawaiian Islands (USA)

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

During 14-20 June 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 (which had many small spattering sites along the margin) 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. Field observations on 31 May revealed that the lava delta had grown to an area of approximately 0.01 square kilometers. A solidified lava ramp extended from the tube exit high on the sea cliff down to the delta, whose leading edge was about 100 m from the tube exit on the sea cliff. Lava flows from the upper portion of the flow field continued to advance downslope, producing surface flows above and on the pali.

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 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, Summit elev. 4754 m

KVERT reported that during 9-16 June explosions at Klyuchevskoy generated ash plumes that rose to 6-7 km (19,700-23,000 ft) a.s.l. and drifted about 580 km SE and SW. A weak thermal anomaly was identified in satellite images during 11-16 June. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

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.

Langila, New Britain (Papua New Guinea)

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

Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that on 14 June ash plumes from Langila rose 1.8 km (6,000 ft) a.s.l. and drifted WNW. On 20 June an ash plume drifted NW at an altitude of 2.1 (7,000 ft) a.s.l.

Geologic 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.

Poas, Costa Rica

10.2°N, 84.233°W, Summit elev. 2708 m

OVSICORI-UNA reported that during 13-15 June gas emissions from Poás rose no higher than 500 m above the crater rim and drifted N. During breaks in weather, observers near the crater on 16 June noted ash emissions rising less than 1 km above the crater rim and drifting N. Ash emissions from events at 1340 on 18 June, and 1100 and 1350 on 20 June, rose less than 1 km.

Geologic 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.

Sabancaya, Peru

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

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya slightly decreased from the previous week; there was an average of 26 explosions recorded per day during 12-18 June. Gas-and-ash plumes rose as high as 3.7 km above the crater rim and drifted more than 40 km SW. The MIROVA system detected nine thermal anomalies, spread over the SE, N, and NW flanks. Sulfur dioxide flux was as high as 3,557 tons per day on 14 June.

Geologic 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.

Sinabung, Indonesia

3.17°N, 98.392°E, Summit elev. 2460 m

Based on PVMBG observations, satellite images, and wind data, the Darwin VAAC reported that during 14-17 and 19 June ash plumes from Sinabung rose 3-6.4 km (10,000-21,000 ft) a.s.l. and drifted in multiple directions.

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 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.

Turrialba, Costa Rica

10.025°N, 83.767°W, Summit elev. 3340 m

OVSICORI-UNA reported that during 14-15 June gas emissions at Turrialba sometimes contained ash and rose no higher than 300 m above the crater. Events at 0620 and 1405 on 16 June generated ash plumes that rose 500 m and drifted NW, and 200 m and drifted S, respectively. Passive ash emissions during 19-20 June rose as high as 1 km and drifted in multiple directions.

Geologic summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m summit depression that is breached to the NE. Most activity originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred during the past 3500 years. A series of explosive eruptions during the 19th century were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

Source: GVP

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