Active volcanoes in the world: August 6 – August 12, 2014

New activity/unrest was observed at 10 volcanoes from August 6 – August 12, 2014. Ongoing activity was reported for 16 volcanoes.

New activity/unrest: Ambang, Sulawesi (Indonesia)  | Bagana, Bougainville (Papua New Guinea)  | Dieng Volcanic Complex, Central Java (Indonesia)  | Etna, Sicily (Italy)  | Ijen, Eastern Java (Indonesia)  | Kelut, Eastern Java (Indonesia)  | Sabancaya, Peru  | Slamet, Central Java (Indonesia)  | Soputan, Sulawesi (Indonesia)  | Stromboli, Aeolian Islands (Italy)

Ongoing activity: Aira, Kyushu (Japan)  | Dukono, Halmahera (Indonesia)  | Fuego, Guatemala  | Kilauea, Hawaiian Islands (USA)  | Kuchinoerabujima, Ryukyu Islands (Japan)  | Kusatsu-Shiranesan, Honshu (Japan)  | Pacaya, Guatemala  | Popocatepetl, Mexico  | Reventador, Ecuador  | San Miguel, El Salvador  | Santa Maria, Guatemala  | Shishaldin, Fox Islands (USA)  | Shiveluch, Central Kamchatka (Russia)  | Tungurahua, Ecuador  | Ubinas, Peru  | Zhupanovsky, Eastern Kamchatka (Russia)

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 on these pages are preliminary and subject to change as events are studied in more detail.

New activity/unrest

Ambang, Sulawesi (Indonesia)
0.75°N, 124.42°E, Summit elev. 1795 m

PVMBG noted that due to decreased volcanic seismicity and activity the Alert Level for Ambang was lowered to 1 (on a scale of 1-4) on 8 August. Residents and visitors were advised to not approach the crater.

Geologic summary: The compound Ambang volcano is the westernmost of the active volcanoes on the northern arm of Sulawesi. The 1795-m-high stratovolcano rises 750 m above lake Danau. Several craters up to 400 m in diameter and five solfatara fields are located at the summit.

Bagana, Bougainville (Papua New Guinea)
6.14°S, 155.195°E, Summit elev. 1750 m

During 6-12 August, DMPGM reported increasing volcanic activity at Bagana volcano. Thin to thick white vapor plumes from Bagana were accompanied on 6, 8 August by reports of rockfalls. On 10 August an ash plume rose to an estimated several hundred meters above the crater drifting SW and W. Moderate ash was reported in Wakovi (6 km W) and decreased downwind. Residents were advised to evacuate to Gotana (9 km SW) if ashfall continued. On 11 August the DarwinVAAC reported ash plumes rose to 3 km (10,000 ft) a.s.l. and drifted up to 55 km SW. On 12 August Darwin VAAC raised the Aviation Color Code to Red as ash plumes rose to 7.6 km (25,000 ft) a.s.l. and drifted up to 167 km SW.

Geologic summary: Bagana volcano, occupying a remote portion of central Bougainville Island, is one of Melanesia's youngest and most active volcanoes. Bagana is a massive symmetrical, roughly 1750-m-high lava cone largely constructed by an accumulation of viscous andesitic lava flows. The entire lava cone could have been constructed in about 300 years at its present rate of lava production. Eruptive activity at Bagana is frequent and is 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 volcano's flanks on all sides.

Dieng Volcanic Complex, Central Java (Indonesia)
7.2°S, 109.92°E, Summit elev. 2565 m

PVMBG noted that due to decreased activity and no observable flow of gas in high concentrations from the crater the Alert Level for Dieng was lowered to 1 (on a scale of 1-4) on 11 August. Residents and visitors were advised to not enter the crater and to be vigilant if excavating to depths greater than 1 m around the crater.

Geologic summary: The Dieng plateau in the highlands of central Java is renowned both for the variety of its volcanic scenery and as a sacred area housing Java's oldest Hindu temples, dating back to the 9th century CE. The Dieng volcanic complex consists of two or more stratovolcanoes and more than 20 small craters and cones of Pleistocene-to-Holocene age over a 6 x 14 km area. Prahu stratovolcano was truncated by a large Pleistocene caldera, which was subsequently filled by a series of dissected to youthful cones, lava domes, and craters, many containing lakes. Lava flows cover much of the plateau, but have not occurred in historical time, when activity has been restricted to minor phreatic eruptions. Toxic volcanic gas emission has caused fatalities and is a hazard at several craters. The abundant thermal features that dot the plateau and high heat flow make Dieng a major geothermal prospect.

Etna, Sicily (Italy)
37.734°N, 15.004°E, Summit elev. 3330 m

On 9 August INGV reported that volcanic tremor decreased and an ash plume rose to 1 km above the July 25 area of Etna and returned to strong Strombolianactivity in the evening. Strombolian activity increased at New Southeast Crater that was accompanied by small emissions of black ash that remained within the crater. The Etna Volcanic Observatory raised the Aviation Color Code to Red on 9 August as an ash plume rose to 4 km (13,000 ft) a.s.l. returning to Orange on 10 August. The Aviation Color Code was raised to Red on 11 August with strong Strombolian activity at Etna accompanied by significant ash.

Geologic summary: Mount Etna, towering above Catania, Sicily's second largest city, has one of the world's longest documented records of historical volcanism, dating back to 1500 BCE. Historical lava flows of basaltic composition cover much of the surface of this massive volcano, whose edifice is the highest and most voluminous in Italy. The Mongibello stratovolcano, truncated by several small calderas, was constructed during the late Pleistocene and Holocene over an older shield volcano. The most prominent morphological feature of Etna is the Valle del Bove, a 5 x 10 km horseshoe-shaped caldera open to the east. Two styles of eruptive activity typically occur at Etna. Persistent explosive eruptions, sometimes with minor lava emissions, take place from one or more of the three prominent summit craters, the Central Crater, NE Crater, and SE Crater (the latter formed in 1978). Flank vents, typically with higher effusion rates, are less frequently active and originate from fissures that open progressively downward from near the summit (usually accompanied by strombolian eruptions at the upper end). Cinder cones are commonly constructed over the vents of lower-flank lava flows. Lava flows extend to the foot of the volcano on all sides and have reached the sea over a broad area on the SE flank.

Ijen, Eastern Java (Indonesia)
8.058°S, 114.242°E, Summit elev. 2799 m

PVMBG noted that due to decreased volcanic seismicity the Alert Level for Ijen was lowered to 1 (on a scale of 1-4) on 11 August. Residents and visitors were advised to not approach the crater rim or crater floor.

Geologic summary: The Ijen volcano complex at the eastern end of Java consists of a group of small stratovolcanoes constructed within the large 20-km-wide Ijen (Kendeng) caldera. The north caldera wall forms a prominent arcuate ridge, but elsewhere the caldera rim is buried by post-caldera volcanoes, including Gunung Merapi stratovolcano, which forms the 2799 m high point of the Ijen complex. Immediately west of Gunung Merapi is the renowned historically active Kawah Ijen volcano, which contains a nearly 1-km-wide, turquoise-colored, acid crater lake. Picturesque Kawah Ijen is the world's largest highly acidic lake and is the site of a labor-intensive sulfur mining operation in which sulfur-laden baskets are hand-carried from the crater floor. Many other post-caldera cones and craters are located within the caldera or along its rim. The largest concentration of post-caldera cones forms an E-W-trending zone across the southern side of the caldera. Coffee plantations cover much of the Ijen caldera floor, and tourists are drawn to its waterfalls, hot springs, and dramatic volcanic scenery.

Kelut, Eastern Java (Indonesia)
7.93°S, 112.308°E, Summit elev. 1731 m

PVMBG noted that due to visual and instrumental monitoring results as well as level of potential hazards the Alert Level for Kelut was lowered to 1 (on a scale of 1-4) on 12 August. Residents and visitors were advised to not approach the crater rim, crater floor, or the rivers that disgorge from Kelut.

Geologic summary: The relatively inconspicuous, 1731-m-high Kelut stratovolcano contains a summit crater lake that has been the source of some of Indonesia's most deadly eruptions. A cluster of summit lava domes cut by numerous craters has given the summit a very irregular profile. Satellitic cones and lava domes are also located low on the eastern, western, and SSW flanks. Eruptive activity has in general migrated in a clockwise direction around the summit vent complex. More than 30 eruptions have been recorded from Gunung Kelut since 1000 CE. The ejection of water from the crater lake during the typically short but violent eruptions has created pyroclastic flows and lahars that have caused widespread fatalities and destruction. After more than 5000 people were killed during an eruption in 1919, an ambitious engineering project sought to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels. After more than 200 deaths in the 1966 eruption, a new deeper tunnel was constructed, and the lake's volume before the 1990 eruption was only about 1 million cubic meters.

Sabancaya, Peru
15.78°S, 71.85°W, Summit elev. 5967 m

IGP reported that on 6 August there was increasing seismic and fumarolic activity at Sabancaya over the past four days. Fumarolic emissions increased, were white to blueish white and gray and rose to 3 km above the crater. On 9 August IGP reported an explosion that lasted 50 seconds at Sabancaya accompanied by increasing seismic activity including a strong increase in hybrid earthquakes. Intermittent views in cloudy conditions showed strong fumarolic emissions continued.

Geologic summary: Sabancaya, located on the saddle between 6288-m-high Ampato and 6025-m-high 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 volcanoes, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. Both Nevado Ampato and Nevado Sabancaya are only slightly affected by glacial erosion and consist of a series of lava domes aligned along a NW-SW trend. The name of 5967-m-high Sabancaya (meaning "tongue of fire" in the Quechua Indian 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.

Slamet, Central Java (Indonesia)
7.242°S, 109.208°E, Summit elev. 3428 m

PVMBG reported that during 1-12 August 100 thick gray ash plumes rose 300-800 m above the summit drifting N, E, and W, seismicity increased, and ejected material was deposited on the flanks 1.5 km from the crater on the W and SW at Slamet. Incandescence and rumbling/roaring noises were reported. The Alert Level was raised to 3 (on a scale of 1-4) on 12 August. Residents and tourists were warned not approach the crater within a radius of 4 km.

Geologic summary: Slamet, Java's second highest volcano at 3428 m and one of its most active, has a cluster of about three dozen cinder cones on its lower SE-NE flanks and a single cinder cone on the western flank. It is composed of two overlapping edifices, an older basaltic-andesite to andesitic volcano on the west and a younger basaltic to basaltic-andesite one on the east. Gunung Malang II cinder cone on the upper E flank on the younger edifice fed a lava flow that extends 6 km E. Four craters occur at the summit of Gunung Slamet, with activity migrating to the SW over time. Historical eruptions, recorded since the 18th century, have originated from a 150-m-deep, 450-m-wide, steep-walled crater at the western part of the summit and have consisted of explosive eruptions generally lasting a few days to a few weeks.

Soputan, Sulawesi (Indonesia)
1.108°N, 124.73°E, Summit elev. 1784 m

PVMBG noted that the Alert Level for Soputan was lowered to 1 (on a scale of 1-4) on 8 August and recommended people not approach within 1.5 km of the summit or within 4 km of the summit on the W.

Geologic summary: The small Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Sempu volcano. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

Stromboli, Aeolian Islands (Italy)
38.789°N, 15.213°E, Summit elev. 924 m

INGV reported that during 6-10 August, a new lava overflow occurred from the crater terrace of Stromboli in the central part of the Sciara del Fuoco. This new lava flow began on 6 August accompanied by large landslides of hot material that reached tens of meters onto the ocean surface. On 7-9 August, a second lava overflow occurred from the north of the crater terrace that covered a plateau at 600 m elevation and six arms of the flow reached the sea. Explosions from lava/sea interactions produced jets of steam, ash and blocks the rose tens of meters into the air that continued 10 August.

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.

Ongoing activity

Aira, Kyushu (Japan)
31.593°N, 130.657°E, Summit elev. 1117 m

JMA reported an explosion from Showa Crater at Aira Caldera’s Sakurajima volcano on 6 August that ejected ballistics 300-500 m from Showa crater and a plume that rose 500 m above the crater. On 10 August three explosions ejected ballistics 500-800 m from Showa crater accompanied by volcanic earthquakes and volcanic tremor. On 6-11 August, incandescence was clearly visible at night by high-sensitivity camera. The Tokyo VAAC reported that plumes from explosions on 6, 8-10 August rose to an altitude of 1.2-2.4 km (4,000-8,000 ft) a.s.l. and drifted NW, N, E, SE, and S. The Alert Level remained at 3 (on a scale of 1-5).

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.

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 on 6 August a low level plume from Dukono rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 93 km NE and that on 8 August a plume from Dukono rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 83 km NE.

Geologic summary: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the north-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time.

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

During 6-12 August, INSIVUMEH reported weak to moderate explosions at Fuego with incandescent blocks being expelled 500-800 m above the crater accompanied by ash that rose 300-400 m above the crater and drifted W and produced rumbling from shock waves that rattled structures up to 8 km from the volcano. On most days, incandescent blocks were expelled 100-200 m above the crater and weak to moderate avalanches of blocks were channeled into the canyons Las Lajas (SE), Trinidad (S), Ceniza (SSW), Taniluyá (SW) and Barranca Honda. Dark gray to white plumes rose 4.0-4.6 km (13,100-15,100 ft) a.s.l. and drifted 8-15 km W and SW. Ashfall was reported in villages of Morelia (9 km SW), Panimaché (8 km SW), Panimaché II, Sangre de Cristo (8 km WSW), Yepocapa (8 km WNW), Hagia Sophia, and around the Observatory. On 6-8 August Washington VAAC reported ongoing emissions and on 7 August an ash plume rose to 4.5 km (15000 ft) a.s.l.

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 6-12 August 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 ash, spatter, and Pele's hair onto nearby areas; smaller particles may have been dropped several kilometers away. On 6 August a small collapse of the north rim and wall of Halema'uma'u Crater temporarily increased spatter on the lava lake surface. 

On 6-12 August HVO reported one small lava pond on the S and glow along the S, SE, and NE edges of the crater floor of Pu?u ?O?o . On August 6 June 27th flow front had encroached on forest 7 Km ENE of Pu?u ?O?o . Monitoring of the volcanoes was disrupted by Hurricane Iselle on 7 August and HVO is working to fully recover from the impacts of the storm. In the interim, staff from the Alaska Volcano Observatory and from USGS Headquarters in Reston, VA have increased satellite monitoring for volcanoes in Hawai’i.

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.

Kuchinoerabujima, Ryukyu Islands (Japan)
30.443°N, 130.217°E, Summit elev. 657 m

JMA reported on 6, 12 August a white plume rose 800m and 300 m respectively above the crater rim at Kuchinoerabujima. Views of the volcano remained obscured by clouds other days, but instruments recorded volcanic seismicity and volcanic tremor. The Alert Level for Kuchinoerabujima remained at 3 (on a scale of 1-5).

Geologic summary: A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyus, 15 km west of Yakushima. Furutake, Shintake, and Noike were erupted from south to north, respectively, to form a composite cone that is parallel to the trend of the Ryukyu Islands. The highest peak, Furutake, reaches only 657 m above sea level. The youngest cone, 640-m-high Shintake, was formed after the NW side of Furutake was breached by an explosion. All historical eruptions have occurred from Shintake, although a lava flow from the S flank of Furutake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shintake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Kusatsu-Shiranesan, Honshu (Japan)
36.618°N, 138.528°E, Summit elev. 2165 m

On 6-8 August, JMA reported volcanic earthquakes continue at Kusatsu-Shiranesan’s crater, although decreased from early August and tremor was absent. The Alert Level remains at 2 (on a scale of 1-5).

Geologic summary: The summit of Kusatsu-Shiranesan volcano, located immediately north of Asama volcano, consists of a series of overlapping pyroclastic cones and three crater lakes. The andesitic-to-dacitic volcano was formed in three eruptive stages beginning in the early to mid Pleistocene. The Pleistocene Oshi pyroclastic flow produced extensive welded tuffs and non-welded pumice that covers much of the east, south and SW flanks. The latest eruptive stage began about 14,000 years ago. All historical eruptions have consisted of phreatic explosions from the acidic crater lakes or their margins. Fumaroles and hot springs that dot the flanks have strongly acidified many rivers draining from the volcano. The crater was the site of active sulfur mining for many years during the 19th and 20th centuries.

Pacaya, Guatemala
14.381°N, 90.601°W, Summit elev. 2552 m

INSIVUMEH reported that during 6-12 August white fumarolic plumes rose 50-75 m above Mackenney Crater at Pacaya and drifted 400-500 m NW, W, SW, and S.

Geologic summary: Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex basaltic volcano constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo volcano between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and was last active in the 19th century. During the past several decades, activity at Pacaya has consisted of frequent strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.

Popocatepetl, Mexico
19.023°N, 98.622°W, Summit elev. 5426 m

CENAPRED reported that during 6-12 August cloudy conditions with intermittent views showed steam-and-gas emissions with minor ash rose above Popocatépetl’s crater. On 7 August there was an explosion and ash was reported in the area of Paso de Cortés. On 9 August there were 5 explosions and ash columns that rose 1 km above the crater. Slight nighttime incandescence was observed. 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.

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

IG reported moderate volcanic activity including explosions, long period earthquakes, harmonic tremor, and tremor at Reventador during 6-12 August. On 6 August a dark gray plume rose 300 m above the summit and drifted NW. On 7, 8 and 10 August steam and steam-and-minor ash rose 300 to 800 m above the summit and drifted SW and NW. On 9 August views of the volcano were obscured by clouds and no report was available 11 August.

Geologic summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well east of the principal volcanic axis. The forested, dominantly andesitic Volcán El Reventador stratovolcano rises to 3562 m above the jungles of the western Amazon basin. A 4-km-wide caldera widely breached to the east was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1300 m above the caldera floor to a height comparable to the caldera rim. It has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. The largest historical eruption took place in 2002, producing a 17-km-high eruption column, pyroclastic flows that traveled up to 8 km, and lava flows from summit and flank vents.

San Miguel, El Salvador
13.434°N, 88.269°W, Summit elev. 2130 m

SNET reported low seismic activity and reduced emissions at San Miguel during 6-12 August. A remote camera and infrared visual display showed mild white fumerolic emissions rose less than 200 m above the crater. Heavy rain has contributed to a debris flow recorded by a station 1.7 km from the north flank on 9 August. On 11 August instruments recorded additional mud flows. SNET reported property damage and two people were affected by these flows.

Geologic 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 of the towering volcano, which is 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.

Santa Maria, Guatemala
14.756°N, 91.552°W, Summit elev. 3772 m

On 6-12 August, INSIVUMEH reported fumarolic columns rose to 2.7-2.8 km (8,800-9,200 ft) a.s.l. above Santiaguito to the S, SW and W. On most days, the lavaflow (2.3 km in length) moved towards and into Nima Canyon I. Collapse avalanches from the flow front generated columns of fine ash that rose 100-200 m above the flow front drifting E. On 9 August ash was reported on the southeast of Finca San José On the evening of 11-12 August INSIVUMEH reported incandescence at the crater.

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.

Shishaldin, Fox Islands (USA)
54.756°N, 163.97°W, Summit elev. 2857 m

AVO reported that during 6-12 August low-level eruptive activity continued at Shishaldin volcano. Web camera and satellite images showed the volcano was mostly cloudy over the past week, but intermittent web camera views showed a steam plume above the summit. On 9-10 August sound waves were detected from the direction of Shishaldin on infrasound sensors in Dillingham, consistent with the low-level activity. On 10 August an area of hot, glowing material was observed in the crater during an overflight of the Shishaldin summit. On 11 August elevated surface temperatures were observed in the summit crater. 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.

Shiveluch, Central Kamchatka (Russia)
56.653°N, 161.36°E, Summit elev. 3283 m

KVERT reported that during 1-7 August lava-dome extrusion onto Shiveluch’s SE flank was accompanied by moderate ash explosions, incandescence of the dome summit, hot avalanches, and fumarolic activity. Satellite data showed a thermal anomaly over the lava dome on 7 August and the volcano was obscured by clouds in the other days of week. The Aviation Color Code remained at Orange.

Geologic summary: The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1300 cu km Shiveluch 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 of Shiveluch 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.

Tungurahua, Ecuador
1.467°S, 78.442°W, Summit elev. 5023 m

During 6-12 August IG reported that moderate to high eruptive activity continued at Tungurahua. On 6, 8-9, and 11 August clouds obscured most views of the volcano, but frequent explosion sounds were heard that, on 9 August, shook structures in areas near and around the volcano. On 7 and 10 August Strombolianactivity expelled incandescent blocks 500 m below the summit; on 7 August the blocks traveled primarily down the W flank. On 7-9 and 11 August ash and steam-and-ash plumes rose 1-1.5 km (3,300-4,900 ft) a.s.l. and drifted W and WNW. On 7 August ash was reported in the town of Quero and 8 August in El Manzano, Pillate, Cahuají and Tisaleo. On 8 August morning rains produced lahars that flowed down the ravines Achupashal, Pingullo and Chontapamba, that interrupted traffic on the Baños-Penipe road. On 9 August night rains caused lahars that flowed down streams Juive and La Pampa. Washington VAAC reported ongoing ash emissions on 6-12 August that, on 7 August, rose 6-6.4 km (20000-21000 ft) a.s.l.

Geologic summary: Tungurahua, a steep-sided andesitic-dacitic stratovolcano that towers more than 3 km above its northern base, is one of Ecuador's most active volcanoes. Three major volcanic edifices have been sequentially constructed since the mid-Pleistocene over a basement of metamorphic rocks. Tungurahua II was built within the past 14,000 years following the collapse of the initial edifice. Tungurahua II itself collapsed about 3000 years ago and produced a large debris-avalanche deposit and a horseshoe-shaped caldera open to the west, inside which the modern glacier-capped stratovolcano (Tungurahua III) was constructed. Historical eruptions have all originated from the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. Prior to a long-term eruption beginning in 1999 that caused the temporary evacuation of the city of Baños at the foot of the volcano, the last major eruption had occurred from 1916 to 1918, although minor activity continued until 1925.

Ubinas, Peru
16.355°S, 70.903°W, Summit elev. 5672 m

During 6-9 August INGEMMET reported that the eruption of Ubinas was continuing. On 6-7 August gas-and-minor ash emissions rose 300-1200 m above the crater and drifted NE and S. On 6 August ash was reported in the village of Para (NE). On 8-9 August, white emissions of primarily water vapor rose 100-300 m above the crater and drifted S and SE. On 6 August Buenos Aires VAAC reported intermittent light volcanic ash and emission puffs to 6.7 km (22,000 ft)a.s.l. and continuous emissions of gases and light ash on 7 August.

Geologic summary: A small, 1.4-km-wide caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. Ubinas 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 volcano was followed by construction of Ubinas II volcano 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 of Ubinas about 3700 years ago extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include one of Holocene age about 1000 years ago. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions.

Zhupanovsky, Eastern Kamchatka (Russia)
53.59°N, 159.147°E, Summit elev. 2958 m

KVERT reported that during 1-7 August that the moderate explosive eruption continues at Zhupanovsky. On 6 August, KVERT reported an ash plume drifting 260 km ENE of the volcano. Most days satellite data showed the volcano was obscured by clouds.

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.

Source: GVP