The Weekly Volcanic Activity Report: October 4 - 10, 2017

The Weekly Volcanic Activity Report: October 4 - 10, 2017

New activity/unrest was reported for 3 volcanoes between October 4 and 10, 2017. During the same period, ongoing activity was reported for 16 volcanoes.

New activity/unrest: Agung, Bali (Indonesia) | Aoba, Vanuatu | Lewotolo, Lomblen Island (Indonesia).

Ongoing activity: Aira, Kyushu (Japan) | Bezymianny, Central Kamchatka (Russia) | Cleveland, Chuginadak Island (USA) | Dukono, Halmahera (Indonesia) | Ebeko, Paramushir Island (Russia) | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaiian Islands (USA) | Langila, New Britain (Papua New Guinea) | Reventador, Ecuador | Rincon de la Vieja, Costa Rica | Sabancaya, Peru | Sangay, Ecuador | Sheveluch, Central Kamchatka (Russia) | Sinabung, Indonesia | Turrialba, Costa Rica.

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 23:00 UTC every Wednesday, notices of volcanic activity posted are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New activity/unrest

Agung, Bali (Indonesia)

8.343°S, 115.508°E, Summit elev. 2995 m

On 5 October PVMBG reported that the rate of volcanic earthquakes at Agung had not increased during the previous 12 days, but continued to fluctuate at a high level. The seismic network detected 1-3 earthquakes per minute on average, with a total more than 600 events per day. The number of shallow volcanic earthquakes increased to 200 per day during 24 September-5 October, possibly indicating that magmatic activity at shallow depths was still high. The number of earthquakes felt by staff at the Mt. Agung Volcano Observatory in Rendang village, 12.5 km SSW, peaked on 27 September and then decreased afterwards. Gas plumes rose 50-200 m above the crater rim. Satellite data indicated an area of water expulsion near the solfatara field on the crater floor thought to reflect a disturbance to the hydrologic system in response to intruded magma at depth. On 5 October BNPB reported that the number of evacuees reached 146,797 (spread out in 427 shelters), though about 28 villages (70,000 people) were located within the evacuation zone. About 10,000 farm animals had also been evacuated. On 7 October a white plume likely composed mostly of water vapor rose 1.5 km above the crater rim and slowly drifted E. During 8-10 October fumarolic plumes rose 50-200 m above the rim. The Alert Level remained at 4 (the highest level on a scale of 1-4) with the exclusion zone at 9 km, and an additional expansion to 12 km in the SE, S, and SW directions.

Geological summary: Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.

Aoba, Vanuatu

15.4°S, 167.83°E, Summit elev. 1496 m

Vanuatu Geohazards Observatory (VGO) stated that photographs and thermal infrared images taken on 30 September, and 1, 3, and 5 October during overflights of Aoba’s Lake Voui confirmed that the eruption was ongoing. Activity consisted of small explosions ejecting hot rock from vents on a new small island in the lake, and a small lava flow that traveled from the vent into the lake. On 6 October VGO noted that there was no evidence of the eruption escalating; the Alert Level was lowered to 3 (the middle level on a scale of 0-5) and residents and tourists were reminded to stay outside of the Red Zone defined as a 3 km radius around the active cone. Based on analyses of satellite imagery and model data, the Wellington VAAC reported that during 10-11 October ash plumes rose as high as 3.7 km (12,000 ft) a.s.l. and drifted N. On 11 October a news article stated that the government extended a state of emergency on the island to 24 October, delaying the return of the 11,000 residents that had been evacuated.

Geological summary: Aoba, also known as Ambae, is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

Lewotolo, Lomblen Island (Indonesia)

8.272°S, 123.505°E, Summit elev. 1423 m

The number of shallow and deep volcanic earthquakes at Lewotolo recently increased, prompting PVMBG to raise the Alert Level from 1 to 2 (on a scale of 1-4) on 7 October. The report noted that the public should not enter the 2-km-radius exclusion zone around the crater. Solfatara emissions rose as high as 500 m above the crater rim on 9 October; emissions during 1 August-6 October rose 50-600 m. BNPB reported that five earthquakes recorded by Badan Meteorologi, Klimatologi, dan Geofisika (BMKG) on 10 October ranged in magnitude between 3.9 and 4.9, and were located 10-30 km below Lewotolo. The events were felt by local populations, causing an evacuation of 723 people. Preliminary data suggested that five homes were damaged from rock avalanches, triggered by the earthquakes.

Geological summary: Anchoring the eastern end of an elongated peninsula that is connected to Lembata (formerly Lomblen) Island by a narrow isthmus and extends northward into the Flores Sea, Lewotolo rises to 1423 m. Lewotolo is a symmetrical stratovolcano as viewed from the north and east. A small cone with a 130-m-wide crater constructed at the SE side of a larger crater forms the volcano's high point. Many lava flows have reached the coastline. Historical eruptions, recorded since 1660, have consisted of explosive activity from the summit crater.

Ongoing activity

Aira, Kyushu (Japan)

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

JMA reported that during 2-10 October there were 19 events detected at Showa Crater (at Aira Caldera’s Sakurajima volcano), three of which were explosive. Plumes rose as high as 1.6 km above the crater rim. An explosion on 5 October ejected material as far as 800 m. The Alert Level remained at 3 (on a 5-level scale).

Geological summary: The Aira caldera in the northern half of Kagoshima Bay contains the post-caldera Sakurajima volcano, one of Japan's most active. Eruption of the voluminous Ito pyroclastic flow accompanied formation of the 17 x 23 km caldera about 22,000 years ago. The smaller Wakamiko caldera was formed during the early Holocene in the NE corner of the Aira caldera, along with several post-caldera cones. The construction of Sakurajima began about 13,000 years ago on the southern rim of Aira caldera and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kitadake summit cone ended about 4850 years ago, after which eruptions took place at Minamidake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76.

Bezymianny, Central Kamchatka (Russia)

55.972°N, 160.595°E, Summit elev. 2882 m

On 6 October KVERT reported that a thermal anomaly at Bezymianny was identified in satellite images during 1-2 and 4-5 October, and that lava probably continued to flow down the W flank of the dome. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale).

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.

Cleveland, Chuginadak Island (USA)

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

AVO reported that no significant activity at Cleveland was observed in seismic or infrasound data during 4-10 October, though elevated surface temperatures identified in satellite data on 6 October suggested that the lava dome in the summit crater (first noted on 30 September) continued to grow. Elevated surface temperatures were identified during 8-9 October. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

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, Summit elev. 1229 m

Based on analyses of satellite imagery, model data, and notices from PVMBG, the Darwin VAAC reported that during 4-10 October ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted N, NW, W, and SW. Ash plumes drifted 140-170 km on 8 October.

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, Summit elev. 1103 m

Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 29-30 September and 1 and 5 October generated ash plumes that rose 1.5 km (4,900 ft) a.s.l. 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.

Fuego, Guatemala

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

CONRED and INSIVUMEH reported that during 4-6 October increased explosive activity (8-12 explosions per hour) at Fuego generating ash plumes that rose as high as 1.3 km above the crater. Ash plumes drifted more than 20 km S, SW, and W; ashfall was reported in areas downwind including Panimaché I and II (8 km SW), Santa Sofía (12 km SW), Morelia (9 km SW), and El Porvenir. Incandescent material rose 300 m above the crater, and avalanches of material traveled as far as 1.5 km W down the Seca (Santa Teresa) ravine and SSW down the Ceniza ravine. Shockwaves vibrated local structures. An average of 4-6 explosions per hour were detected during 7-8 October. Ash plumes rose around 1 km and drifted 12 km W, NW, and N. Incandescent material was ejected 150 m above the crater, causing avalanches that were confined to the crater. Ash fell in local communities including San Pedro Yepocapa (8 km N), Sangre de Cristo (8 km WSW), and La Soledad. Vulcanian explosions during 8-9 October produced ash plumes that rose 1 km and drifted 15 km SW, W, and NW, again causing ashfall in Panimaché, Santa Sofía, Morelia, El Porvenir, San Pedro Yepocapa, and Sangre de Cristo. Block avalanches traveled 2 km down the flanks.

Geological 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.

Karymsky, Eastern Kamchatka (Russia)

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

KVERT reported that an ash cloud was identified in satellite images drifting about 85 km ENE from Karymsky on 3 October. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale).

Geological 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

During 4-10 October 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 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 although the plume at the entry was weaker. Surface lava flows were active above and on the pali, and on the coastal plain.

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.

Langila, New Britain (Papua New Guinea)

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

Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 4 October a minor ash emission from Langila rose 1.8 km (6,000 ft) a.s.l. and drifted N.

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.

Reventador, Ecuador

0.077°S, 77.656°W, Summit elev. 3562 m

During 3-10 October IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador. Steam, gas, and ash plumes rose sometimes higher that 1.1 km above the crater rim and drifted mainly NW, W, and SW. Incandescent blocks rolled as far as 800 m down the flanks. Weather clouds sometimes prevented visual observations.

Geological 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.

Rincon de la Vieja, Costa Rica

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

OVSICORI-UNA reported that at 1048 on 9 October a small eruption at Rincón de la Vieja produced a plume that rose 700 m above the crater rim.

Geological 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 km3 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 km3 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 active crater containing a 500-m-wide acid lake located ENE of Von Seebach crater.

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 declined; there was an average of 42 explosions recorded per day during 2-8 October. The earthquakes were dominated by long-period events, with fewer numbers of signals indicating emissions and hybrid events. Gas-and-ash plumes rose 3.5 km above the crater rim and drifted no more than 40 km N, NW, and W. The MIROVA system detected 10 thermal anomalies. The report warned the public not to approach the crater within a 12-km radius.

Geological summary: Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of historical eruptions date back to 1750.

Sangay, Ecuador

2.005°S, 78.341°W, Summit elev. 5286 m

In a special report from 4 October IG stated that the current eruption at Sangay which began on 20 Julycontinued, and that the activity had not changed significantly during the previous two months. Activity was characterized by explosions at the central vent and lava from the Ñuñurco lava dome flowing down the E and ESE flanks. On each day during the previous week there were about 65 explosions, 25 long-period events, and a few harmonic tremor signals. Ash plumes rose 1 km above the crater rim and caused ashfall in areas to the W and NW (Culebrillas and Licto (35 km NW)).

Geological summary: The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands. The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex.

Sheveluch, Central Kamchatka (Russia)

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

KVERT reported that a thermal anomaly over Sheveluch was identified daily in satellite images on 2 and 5 October. The Aviation Color Code remained at Orange.

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.

Sinabung, Indonesia

3.17°N, 98.392°E, Summit elev. 2460 m

Based on observations by PVMBG and BMKG, webcam and satellite images, and model data, the Darwin VAAC reported that during 4-5 and 7-9 October ash plumes from Sinabung rose 3-5.8 km (10,000-19,000 ft) a.s.l. and drifted in multiple directions.

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.

Turrialba, Costa Rica

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

OVSICORI-UNA reported that an event at Turrialba at 0815 on 6 October produced a plume that rose 50 m above the crater rim and drifted NW. An event at 1040 on 9 October generated a plume that rose 200 m and drifted NW.

Geological 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

Comments

MARGARETE FRATTAROLI 2 days ago

How did you miss this one in Japan: Sakurajima volcano in Japan erupts

TW (@MARGARETE FRATTAROLI) 2 days ago

Didn't miss. That's Aira. It's 'always' erupting and 'always' in The Weekly.

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