During past seven days 9 volcanoes had new activity, ongoing activity was reported for 13 volcanoes. This report covers active volcanoes in the world from August 28 – September 3, 2013 based on Smithsonian/USGS criteria.
New activity/unrest: | Dukono, Halmahera | Guntur, Western Java (Indonesia) | Iliwerung, Indonesia | Karangetang [Api Siau], Siau | Kliuchevskoi, Central Kamchatka (Russia) | Sakura-jima, Kyushu | Santa María, Guatemala | Suwanose-jima, Ryukyu Islands and Kyushu | Ubinas, Perú
Ongoing activity: | Batu Tara, Komba Island (Indonesia) | Chirinkotan, Kuril Islands| Chirpoi, Kuril Islands (Russia) | Fuego, Guatemala | Karymsky, Eastern Kamchatka (Russia) | Ketoi, Kuril Islands (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Manam, Northeast of New Guinea (SW Pacific) | Popocatépetl, México | Rabaul, New Britain | Shiveluch, Central Kamchatka (Russia) | Veniaminof, Alaska Peninsula
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 2300 UTC every Wednesday, notices of volcanic activity posted on these pages 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, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
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 29 August and during 31 August-3 September ash plumes from Dukono rose to altitudes of 2.4-3 km (8,000-10,000 ft) a.s.l. and drifted 80-240 km W and NW.
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 N-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.
GUNTUR, Western Java (Indonesia)
7.143°S, 107.840°E; summit elev. 2249 m
CVGHM reported that the number of deep and shallow volcanic earthquakes at Guntur increased during 15-21 August; seismicity declined after that period. On 30 August at 0820 seismicity again increased, characterized by continuous tremor that lasted until 1450. At 1600 CVGHM raised the Alert Level to 2 (on a scale of 1-4) and reminded residents and visitors not to approach the active crater within a 2-km radius.
Geologic summary: Guntur is a complex of several overlapping stratovolcanoes about 10 km NW of the city of Garut in western Java. Young lava flows, the most recent of which was erupted in 1840, are visible on the flanks of the erosionally unmodified Gunung Guntur, which rises about 1,550 m above the plain of Garut. Guntur is one of a group of younger cones constructed to the SW of an older eroded group of volcanoes at the NE end of the complex. Guntur, whose name means "thunder," is the only historically active center, with eruptions having been recorded since the late-17th century. Although Guntur produced frequent explosive eruptions in the 19th century, making it one of the most active volcanoes of western Java, it has not erupted since.
ILIWERUNG, Lesser Sunda Islands, Indonesia
8.54°S, 123.59°E; summit elev. 1,018 m
CVGHM reported that observers at a post 6 km away from Iliwerung reported that diffuse fumarolic emissions from the crater were visible during the mornings from 19 August to 1 September. Seismicity decreased on 19 August and remained at normal levels. On 2 September the Alert Level was lowered to 1 (on a scale of 0-4).
Geologic summary:. Constructed on the southern rim of the Lerek caldera, Iliwerung forms a prominent S-facing peninsula on Lomblen Island. Craters and lava domes have formed along N-S and NW-SE lines on the complex volcano; during historical time vents from the summit to the submarine SE flank have been active. The Iliwerung summit lava dome was formed during an eruption in 1870. In 1948 Iligripe lava dome grew on the eastern flank at 120 m altitude. Beginning in 1973-74, when three ephemeral islands were formed, submarine eruptions began on the lower SE flank at a vent named Hobal; several other eruptions took place from this vent before the end of the century.
KARANGETANG [API SIAU], Siau
I 2.78°N, 125.40°E; summit elev. 1784 m
Based on observations from the post in Salili, CVGHM reported that, although Karangetang was sometimes covered in fog during 1 August-2 September, white plumes were seen rising as high as 500 m above the main crater and as high as 300 m above Crater II. Incandescence from the crater was often observed at night. Avalanches began traveling down the Batuawang drainage on 2 September and then intensified the next day. The Alert Level was raised to 3 (on a scale of 1-4) on 3 September.
Geologic summary: Karangetang (also known as Api Siau) lies at the northern end of the island of Siau, N of Sulawesi, and contains five summit craters strung along a N-S line. One of Indonesia's most active volcanoes, Karangetang has had more than 40 recorded eruptions since 1675. Twentieth-century eruptions have included frequent explosions, sometimes accompanied by pyroclastic flows and lahars.
KLIUCHEVSKOI, Central Kamchatka (Russia)
56.057°N, 160.638°E; summit elev. 4850 m
KVERT reported that moderate seismic activity at Kliuchevskoi was detected during 23-30 August. A video camera recorded incandescence from the summit at night and gas-and-steam plumes containing minor amounts of ash. A large thermal anomaly from the lava dome was detected in satellite images. Strombolian activity that began on 15 August continued; a new lava flow effused onto the SW flank on 26 August, producing a thermal anomaly detected in satellite images. The Aviation Color Code remained at Yellow.
Geologic summary: Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. Kliuchevskoi rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred at Kliuchevskoi during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that 34 explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m during 26-30 August. Incandescence from the crater was visible at night on 26 August. An explosion on 29 August at 0927 generated an ash plume that rose 3 km and caused ashfall in areas from Miyazaki (80 km NW) to Kagoshima (12 km W). Tephra 1 cm in diameter was confirmed in an area 4 km E.
Based on information from JMA, the Tokyo VAAC reported that during 28 August-3 September explosions generated plumes most days that rose to altitudes of 1.5-4 km (5,000-13,000 ft) a.s.l. and drifted E, NE, and NW. On 31 August a pilot observed an ash plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and traveled NE.
Geologic summary: Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. 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.
SANTA MARIA, Guatemala
14.756°N, 91.552°W; summit elev. 3772 m
INSIVUMEH reported that during 28-29 August abundant degassing at Santa María's Santiaguito lava-dome complex generated gas plumes that rose 2.7 km. During 29-31 August explosions produced ash plumes that rose 700-900 m and sometimes drifted SW. Block avalanches descended the S and E flanks. On 31 August a lahar traveled down the Nima I drainage on the S flank carrying 2-m-diameter blocks, tree branches, and tree trunks. Cloud cover prevented views on 2 September. Overnight during 2-3 September explosions generated ash plumes that rose 700 m and drifted SW. Block avalanches descended the S flank.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large 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, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
29.635°N, 129.716°E; summit elev. 799 m
According to the Tokyo VAAC, the JMA reported that on 28 August pilots observed ash plumes from Suwanose-jima that rose to altitudes of 3-3.7 km (10,000-12,000 ft) a.s.l. and drifted E and NW. Explosions during 28-29 August generated ash plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE. Ash was detected in satellite images on 29 August, and explosions were detected on 30 August and 1 September.
Geologic summary: The 8-km-long, spindle-shaped island of Suwanose-jima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. Only about 50 persons live on the sparsely populated island. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanose-jima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from On-take (Otake), the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of On-take collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884.
16.355°S, 70.903°W; summit elev. 5672 m
IGP reported six phreatic explosions from Ubinas during 1-3 September. The series of explosions decreased in both energy and length of the tremor signal associated with each explosion; tremor lasted 75 minutes for the first explosion and 5-10 minutes for the last one. Most of the explosions generated ash plumes that rose 1.5-2 km above the crater.
The first explosion occurred at 2246 on 1 September, lasted 110 seconds, ejected ballistics up to 2 m in diameter, and caused ashfall 2 km ENE. The second explosion, at 1552 on 2 September, lasted 292 seconds and ejected fewer ballistics. Details for the 3rd through the 6th explosions are as follows: the 3rd occurred at 2350 on 2 September and lasted 279 seconds; the 4th occurred at 0809 on 3 September and lasted 296 seconds; the 5th occurred at 1021 on 3 September and lasted 288 seconds; the 6th occurred at 1029 on 3 September and lasted 74 seconds.
Geologic summary: A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives 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 Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, 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 extend 10 km from the volcano. Widespread Plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions.
BATU TARA, Komba Island (Indonesia)
7.792°S, 123.579°E; summit elev. 748 m
Based on analyses of satellite imagery and wind data, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 2-3 September ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 75 km W.
Geologic summary: The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
CHIRINKOTAN, Kuril Islands
48.980°N, 153.480°E; summit elev. 724 m
SVERT reported that a thermal anomaly from Chirinkotan was detected in satellite images on 1 September. The Aviation Color Code remained at Yellow.
Geologic summary: The small, mostly unvegetated 3-km-wide island of Chirinkotan occupies the far end of an E-W-trending volcanic chain that extends nearly 50 km west of the central part of the main Kuril Islands arc. Chirinkotan is the emergent summit of a volcano that rises 3000 m from the floor of the Kuril Basin. A small 1-km-wide caldera about 300-400 m deep is open to the SE. Lava flows from a cone within the breached crater reached the north shore of the island. Historical eruptions have been recorded at Chirinkotan since the 18th century. Fresh lava flows also descended the SE flank of Chirinkotan during an eruption in the 1880s that was observed by the English fur trader Captain Snow.
CHIRPOI, Kuril Islands (Russia)
46.525°N, 150.875°E; summit elev. 742 m
SVERT reported that a thermal anomaly from Snow, a volcano of Chirpoi, was detected in satellite images on 1 September. 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. Two volcanoes on Chirpoi Island have been historically active. 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.
14.473°N, 90.880°W; summit elev. 3763 m
INSIVUMEH reported that during 28-31 August explosions from Fuego generated ash plumes that rose 450-550 m and drifted 8-10 km W and NW. During 28-29 August incandescent material was ejected 150 m high, and white plumes rose 350 m and drifted NW. During 30-31 August rumbling was heard 15 km away. Lava flows 200 m long were active in the Trinidad drainage on the S flank and produced avalanches. In a special bulletin on 2 September, INSIVUMEH reported that a series of pyroclastic flows descended the Ceniza (SSW) drainage, reaching the base of the volcano. Ash plumes rose 3 km and drifted E, S, W, and NW. During the night lava from the crater flowed 300-400 m down the Ceniza drainage. Explosions were heard, but cloud cover prevented observations through the morning of 3 September.
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 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that moderate seismic activity at Karymsky was detected during 23-30 August. Based on seismic interpretation, possible ash plumes rose to an altitude of 3.5 km (11,500 ft) a.s.l. Satellite imagery showed a weak thermal anomaly on the volcano during 26-27 August. The Aviation Color Code remained at Orange.
Geologic summary: Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-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. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996.
KETOI, Kuril Islands (Russia)
47.35°N, 152.475°E; summit elev. 1172 m
SVERT reported that a possible thermal anomaly over Ketoi's Pallas Peak was detected in satellite images on 26 August and 1 September. The Aviation Color Code remained at Yellow.
Geologic summary: The circular, 10-km-wide Ketoi island, which rises across the 19-km-wide Diana Strait from Simushir Island, hosts of one of the most complex volcanic structures of the Kuril Islands. The rim of a 5-km-wide Pleistocene caldera is exposed only on the NE side. A younger 1172-m-high stratovolcano forming the NW part of the island is cut by a horst-and-graben structure containing two solfatara fields. A 1.5-km-wide freshwater lake fills an explosion crater in the center of the island. Pallas Peak, a large andesitic cone in the NE part of the caldera, is truncated by a 550-m-wide crater containing a brilliantly colored turquoise crater lake. Lava flows from Pallas Peak overtop the caldera rim and descend nearly 5 km to the SE coast. The first historical eruption of Pallas Peak, during 1843-46, was its largest.
KILAUEA, Hawaii (USA)
19.421°N, 155.287°W; summit elev. 1222 m
During 28 August-2 September HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater; the lake level was 45-52 m below the Halema'uma'u crater floor during 30-31 August and 2-3 September. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas.
At Pu'u 'O'o Crater, glow emanated from spatter cones on the N and S portions of the crater floor. The Kahauale’a 2 lava flow, fed by the NE spatter cone, was active with scattered break-out flows and burned the forest N of Pu'u 'O'o. A small and brief lava flow issued from the NE spatter cone on 30 August. Peace Day activity, fed by lava tubes extending from Pu'u 'O'o, consisted of some breakouts on the pali and coastal plain. A brief plume near the ocean entry on 2 September possibly signified a small bench collapse.
Geologic summary: Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 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.
KIZIMEN, Eastern Kamchatka (Russia)
55.130°N, 160.32°E; summit elev. 2376 m
KVERT reported that during 23-30 August moderate seismic activity continued at Kizimen. Video and satellite data showed that lava continued to extrude from the summit, producing incandescence, strong gas-and-steam activity, and hot avalanches on the W and E flanks. A thermal anomaly was detected daily in satellite images. The Aviation Color Code remained at Orange.
Geologic summary: Kizimen is an isolated, conical stratovolcano that is morphologically similar to Mount St. Helens prior to its 1980 eruption. The summit of Kizimen consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2,376-m-high Kizimen was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2,000-3,500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of longterm lava-dome growth have occurred. The latest eruptive cycle began about 3,000 years ago with a large explosion and was followed by lava-dome growth lasting intermittently about 1,000 years. An explosive eruption about 1,100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. A single explosive eruption, during 1927-28, has been recorded in historical time.
MANAM, Northeast of New Guinea (SW Pacific)
4.080°S, 145.037°E; summit elev. 1807 m
RVO reported that Manam's Southern Crater was quiet during 16-17 August. Occasional light-gray emissions observed during 18-20, 22-23, and 25 August rose 100 m above the crater and drifted NW. Incandescence from the crater was seen during 18-19 and 21-26 August, and incandescent fragments were ejected during 21-25 August.
A small eruption began at 1830 on 26 August with emissions of dark ash clouds that rose 500-600 m. Bright incandescence from the crater and occasional ejected incandescent fragments were observed. Roaring and rumbling was heard by island residents as well as residents in Bogia, 25-30 km SSW of Manam on the N coast of the mainland. By the next morning the emissions decreased and were light gray to brown.
Geologic summary: The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys," regularly spaced 90 degrees apart, channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE avalanche valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded at Manam since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
19.023°N, 98.622°W; summit elev. 5426 m
CENAPRED reported that during 28 August-3 September seismicity at Popocatépetl indicated continuing emissions; cloud cover sometimes prevented observations of the crater. Incandescence from the crater was observed on most nights. On 28 August gas, steam, and ash plumes rose 200-800 m and drifted SW. Gas-and-steam plumes were observed the next day. On 30 August gas and steam plumes that sometimes contained ash rose 1 km above the crater and drifted W. During 1-2 September steam and gas plumes containing minor amounts of ash drifted WSW. Ashfall was reported in Tetela del Volcán (20 km SW) and Ocuituco (24 km SW) on 1 September, and in Ecatzingo (15 km SW) on 2 September. The Alert Level remained at to Yellow, Phase Two.
Geologic summary: Popocatépetl, whose name is the Aztec word for smoking mountain, towers to 5,426 m 70 km SE of Mexico City and is North America's second-highest volcano. Frequent historical eruptions have been recorded since the beginning of the Spanish colonial era. A small eruption on 21 December 1994 ended five decades of quiescence. Since 1996 small lava domes have incrementally been constructed within the summit crater and destroyed by explosive eruptions. Intermittent small-to-moderate gas-and-ash eruptions have continued, occasionally producing ashfall in neighboring towns and villages.
RABAUL, New Britain
4.271°S, 152.203°E; summit elev. 688 m
Based on observations of satellite imagery and wind data analyses, the Darwin VAAC reported that on 29 August ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted almost 40 km NW.
Geologic summary: The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay. Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.
SHIVELUCH, Central Kamchatka (Russia)
56.653°N, 161.360°E; summit elev. 3283 m
Based on visual observations and analyses of satellite data, KVERT reported that during 23-30 August a viscous lava flow effused onto the N and NW flanks of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. A thermal anomaly was detected daily in satellite images. 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 and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964.
VENIAMINOF, Alaska Peninsula
56.17°N, 159.38°W; summit elev. 2507 m
AVO reported that during 27-29 August seismicity at Veniaminof was characterized by discreet episodic tremor bursts, likely associated with lava effusion and minor ash emissions. Satellite images detected prominent thermal anomalies at the intracaldera cone. Activity increased on 30 August and was some of the strongest detected since the eruption began in early June; intense seismicity, lava fountaining, and ash emissions to 4.6-6.1 km (15,000-20,000 ft) a.s.l. were observed. Ash plumes drifted SE and caused ashfall in areas downwind including Perryville (32 km SSE). Elevated and continuous tremor persisted during 31 August-3 September; cloud cover and fog obscured web-cam and satellite views. The Volcano Alert Level remained at Watch and the Aviation Color code remained at Orange.
Geologic summary: Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 years ago. The caldera rim is up to 520 m high on the N, is deeply notched on the W by Cone Glacier, and is covered by an ice sheet on the S. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which reaches an elevation of 2,156 m and rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.