New activity/unrest was observed at 5 volcanoes from October 8 - 14, 2014. Ongoing activity was reported for 13 volcanoes.
New activity/unrest: Copahue, Central Chile-Argentina border | Mayon, Luzon (Philippines) | Ontakesan, Honshu (Japan) | Poas, Costa Rica | Sinabung, Indonesia
Ongoing activity: Aira, Kyushu (Japan) | Bardarbunga, Iceland | Chirpoi, Kuril Islands (Russia) | Dukono, Halmahera (Indonesia) | Fuego, Guatemala | Kilauea, Hawaiian Islands (USA) | Popocatepetl, Mexico | Santa Maria, Guatemala | Sheveluch, Central Kamchatka (Russia) | Shishaldin, Fox Islands (USA) | Stromboli, Aeolian Islands (Italy) | Ubinas, Peru | Zhupanovsky, Eastern Kamchatka (Russia)
Copahue, Central Chile-Argentina border
37.856°S, 71.183°W, Summit elev. 2953 m
SERNAGEOMIN reported that two explosions from Copahue’s El Agrio Crater occurred at 0752 and 1349 on 11 October, and generated dark gray ash plumes that rose at most 3.6 km above the crater. Some minor explosions were detected after the second explosion. Incandescence in the vicinity of the crater was observed at night. The Alert Level was raised to Orange. Cameras near the volcano recorded dark gray ash plumes rising to a maximum height of 1.9 km and drifting 35 km NE on 12 October, 2.2 km and drifting E on 13 October, and 0.4 km and drifting E on 14 October. Minor explosions continued to be detected.
Geologic summary: Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.
Mayon, Luzon (Philippines)
13.257°N, 123.685°E, Summit elev. 2462 m
PHIVOLCS reported that during 8-12 October white plumes rose from Mayon's crater and drifted NW, NE, ESE, SE, and SSW. During an overflight of Mayon on 12 October volcanologists observed a 350-m-long lava flow traveling down the SE flank, on the E side of Bonga Gully. The report noted that the small number of volcanic earthquakes and rockfall signals recorded during the previous few days indicated slow lava extrusion from the crater and a slow-moving lava flow. The Alert Level remained at 3 (on a 0-5 scale).
Geologic summary: Beautifully symmetrical Mayon volcano, which rises to 2462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes averaging 35-40 degrees that are capped by a small summit crater. Historical eruptions at this basaltic-andesitic volcano date back to 1616 and range from strombolian to basaltic plinian, with cyclical activity beginning with basaltic eruptions, followed by longer term andesitic lava flows. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1200 people and devastated several towns.
Ontakesan, Honshu (Japan)
35.893°N, 137.48°E, Summit elev. 3067 m
JMA reported that during 8-9 October ash emissions from Ontakesan continued. The plume turned white on 10 October, but during 10-14 October the emissions may have contained small amounts of ash. Tremor was below detection limits during 8-14 October. A news article from 12 October noted that the number of people killed in the 27 September eruption had reached 56; seven more were still missing. The Alert Level remained at 3 (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. 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 the mountain had many hikers, resulted in more than 30 fatalities.
Poas, Costa Rica
10.2°N, 84.233°W, Summit elev. 2708 m
OVSICORI-UNA reported that a strong phreatic eruption from the hot lake at Poás was recorded at 1745 on 8 October. The event lasted one minute and ejected material over 250 m above the crater lake’s surface. The seismic record indicated that it was the most energetic event so far in 2014.
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.
3.17°N, 98.392°E, Summit elev. 2460 m
The Darwin VAAC reported that an eruption from Sinabung, observed in the webcam at 1248 on 8 October, generated a pyroclastic flow. An ash plume rose to an altitude of 4.9 km (16,000 ft) a.s.l. (based on webcam views and wind models) and drifted E. Eruptions recorded at 0636 and 1107 on 9 October generated ash plumes that rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted NE, based on webcam views and wind models. On 10 October satellite images and the webcam detected an ash plume drifting 55 km NE. An ash plume drifting SW at an altitude of 3 km (10,000 ft) a.s.l. was recorded by the webcam on 11 October. On 14 October an ash plume was again recorded by the webcam and rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted SW.
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 of Sinabung 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.
Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m
JMA reported that six explosions from Showa Crater at Aira Caldera’s Sakurajima volcano ejected tephra as far as 1,300 m during 6-10 October. Incandescence from Showa Crater was visible at night. The Alert Level remained at 3 (on a scale of 1-5). The Tokyo VAAC reported that during 9-10 October plumes rose to altitudes of 1.5-1.8 km (5,000-6,000 ft) a.s.l. and drifted W.
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.
64.63°N, 17.53°W, Summit elev. 2009 m
During 8-14 October, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. Subsidence of the Bárdarbunga Caldera continued. The lava field continued to grow, with lava production unchanged. Seismic activity was low in the N part of the dyke and around the eruption site.
Geologic summary: The large central volcano of Bárdarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 cu km, have occurred throughout the Holocene into historical time from the Veidivötn fissure system. The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system located SW of Bárdarbunga volcano is also part of the Bárdarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárdarbunga potentially affect drainages in all directions.
Chirpoi, Kuril Islands (Russia)
46.525°N, 150.875°E, Summit elev. 742 m
SVERT reported that satellite images over Snow, a volcano of Chirpoi, showed a thermal anomaly on 6, 9, and 12 October. Cloud cover obscured views on other days during 7-13 October. The Aviation Color Code remained at Yellow.
Geologic summary: Chirpoi, a small island lying between the larger islands of Simushir and Urup, contains a half dozen volcanic edifices constructed within an 8-9 km wide, partially submerged caldera. The southern rim of the caldera is exposed on nearby Brat Chirpoev Island. The symmetrical Cherny volcano, which forms the 691 m high point of the island, erupted twice during the 18th and 19th centuries. The youngest volcano, Snow, originated between 1770 and 1810. It is composed almost entirely of lava flows, many of which have reached the sea on the southern coast. No historical eruptions are known from 742-m-high Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.
Dukono, Halmahera (Indonesia)
1.68°N, 127.88°E, Summit elev. 1335 m
Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 8-9 and 14 October ash plumes from Dukono rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 75-95 km NNE and ENE.
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.
14.473°N, 90.88°W, Summit elev. 3763 m
INSIVUMEH reported that during 11-12 October explosions at Fuego produced ash plumes that rose 1,650-1,950 m above the crater and drifted 10-12 km WSW. Explosions ejected incandescent tephra 150 m above the crater and generated shock waves that rattled structures within a 13-km radius. Ashfall was reported in Panimaché (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), San Pedro, and Yepocapa (8 km NW). During 12-14 October explosions produced ash plumes that rose 500-800 m above the crater and drifted 7-12 km S and SW. Incandescent pulses rose 100-150 m above the crater. During 13-14 explosions rattled structures in Morelia, Panimache, and Sangre de Cristo, and incandescent blocks from the crater were observed at night.
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.
Kilauea, Hawaiian Islands (USA)
19.421°N, 155.287°W, Summit elev. 1222 m
During 8-14 October HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Gas emissions remained elevated. The plume from the vent continued to deposit variable amounts of tephra onto nearby areas; smaller particles may have been dropped several kilometers away. At Pu'u 'O'o Crater, glow emanated from several outgassing openings in the crater floor.
The 27 June NE-trending lava flow continued to advance. Volcanologists aboard an overflight on 13 October noted that the flow had advanced about 220 m since 10 October, with an average travel rate of approximately 75 m/day since 6 October. The leading edge of the flow was 1.4 km upslope from Apa’a Street. Vegetation along the flow margins was burning. An overflight on 14 October revealed that the flow had advanced an additional 40 m. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Warning.
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.
19.023°N, 98.622°W, Summit elev. 5426 m
CENAPRED reported that during 7-13 October seismicity at Popocatépetl indicated continuing emissions of water vapor, gas, and occasional small amounts of ash. Incandescence from the crater was observed at night during 9-10 October. Cloud cover often prevented visual observations, although steam-and-gas plumes were observed daily. During 7-8 October ash plumes rose 1 km and drifted W. Ashfall was reported in Cuautla (43 km SW), Tetela del Volcán (20 km SW), Huaquechula (30 km SSW), and Morelos (60 km SW). On 9 October ash plumes rose 800 m and drifted NW. Gas-and-ash plumes on 10 October rose 1.4 km and drifted NW. On 12 October ash plumes rose 2 km and drifted NE. Ashfall was reported in Paso de Cortés (8 km NNW) and Tlalmanalco (30 km NW). The Alert Level remained at to 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.
Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m
Although cloud cover prevented visual observations of Santa María's Santiaguito lava-dome complex, during 11-12 October INSIVUMEH reported that the lava-flow front remained active. During 12-13 October avalanches from the flow fronts descended the E flank.
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 of Volcán Santa María 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 3-10 October lava-dome extrusion onto Sheveluch’s N flank was accompanied by ash explosions, incandescence, hot avalanches, and fumarolic activity. Satellite images detected a thermal anomaly over the dome during 3 and 8-9 October; cloud cover prevented views of 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, although cloud cover often obscured views of Shishaldin during 8-14 October, seismicity indicated a low-level eruption was likely continuing. Strongly elevated surface temperatures at the summit were periodically detected in cloud-free satellite images during 10-11 and 13-14 October. Tremor and ground-coupled airwaves from small explosions were occasionally detected in seismic data. 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.
Stromboli, Aeolian Islands (Italy)
38.789°N, 15.213°E, Summit elev. 924 m
Based on SIGMET notices, the Toulouse VAAC reported that ash from Stromboli was detected below an altitude of 3 km (10,000 ft) a.s.l. during 8-10 October however ash was not detected in good satellite views.
Geologic summary: Spectacular incandescent nighttime explosions at Stromboli volcano have long attracted visitors to the "Lighthouse of the Mediterranean." Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout much of historical time. The small, 924-m-high island of Stromboli is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The Neostromboli eruptive period from about 13,000 to 5000 years ago was followed by formation of the modern Stromboli edifice. The active summit vents are located at the head of the Sciara del Fuoco, a prominent horseshoe-shaped scarp formed about 5000 years ago as a result of the most recent of a series of slope failures that extend to below sea level. The modern volcano has been constructed within this scarp, which funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild strombolian explosions, sometimes accompanied by lava flows, have been recorded at Stromboli for more than a millennium.
16.355°S, 70.903°W, Summit elev. 5672 m
IGP and INGEMMET reported that the Alert Level for Ubinas was lowered to Yellow on 10 October; seismicity, the number of explosions, and sulfur dioxide output had all declined. The report noted that sporadic ash emissions as well as explosions were expected to continue.
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 an explosive eruption at Zhupanovsky continued during 3-10 October. Satellite images detected a thermal anomaly on 3 and 9 October; cloud cover prevented views of the volcano on the other days. 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.