Active volcanoes in the world: August 7 – August 13, 2013

During past seven days 3 volcanoes had new activity, ongoing activity was reported for 12 volcanoes. This report covers active volcanoes in the world from August 7 – August 13, 2013 based on Smithsonian/USGS criteria.

New activity/unrest: | Ketoi, Kuril Islands (Russia) | Paluweh, Lesser Sunda Islands (Indonesia) | Tungurahua, Ecuador

Ongoing activity: | Chirinkotan, Kuril Islands| Chirpoi, Kuril Islands (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Pacaya, Guatemala | Pavlof, Alaska Peninsula | Reventador, Ecuador | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Tolbachik, 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.

New activity/unrest

KETOI, Kuril Islands (Russia) 
47.35°N, 152.475°E; summit elev. 1172 m

SVERT reported that a thermal anomaly over Ketoi's Pallas Peak was detected in satellite images during 5-7 and 9 August, and possibly during 10-11 August. Steam-and-gas emissions were detected on 9 August. 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.

PALUWEH, Lesser Sunda Islands (Indonesia)
8.32°S, 121.708°E; summit elev. 875 m

According to news articles, a partial lava-dome collapse at Paluweh on 10 August generated a pyroclastic flow that traveled N towards a beach village and killed at least 5 people. A volcanologist at the monitoring post for Paluweh noted that the eruption lasted seven minutes, and that the pyroclastic flow burned trees around the beach and villages, making it difficult to reach the victims. Pyroclastic flows continued to be reported hours after the initial eruption. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that an ash plume rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted 130 km W.

News sources noted that a mandatory evacuation order had caused some residents to evacuate prior to the eruption on 10 August, but nearly 10,000 still remained on the island. After the eruption, a rescue team was sent to evacuate about 2,000 people that remained inside a 3-km exclusion zone. A team member noted that rescuing people was difficult since they were reluctant to leave their livestock and homes, but also that the ground was hot and covered in 10-20 cm of ash. The VAAC reported that during 11-12 August ash plumes rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted 110-130 km W. A news article noted that the eruptions were smaller on 12 August, but pyroclastic flows continued to be observed. The Alert Level remained at 3 (on a scale of 0-4).

Geologic summary:  Paluweh volcano, also known as Rokatenda, forms the 8-km-wide island of Paluweh N of the volcanic arc that cuts across Flores Island. Although the volcano rises about 3,000 m above the sea floor, its summit reaches only 875 m above sea level. The broad irregular summit region contains overlapping craters up to 900 m wide and several lava domes. Several flank vents occur along a NW-trending fissure. The largest historical eruption of Paluweh occurred in 1928, when a strong explosive eruption was accompanied by landslide-induced tsunamis and lava-dome emplacement.

TUNGURAHUA, Ecuador 
1.467°S, 78.442°W; summit elev. 5023 m

IG reported that seismic activity at Tungurahua was moderate to high during 7-13 August; the seismic network detected long-period earthquakes indicating fluid movement and some emissions. Although cloud cover mostly prevented visual observations of the crater, plumes were occasionally observed. On 8 August an ash plume rose 2 km and drifted W, and ash fell in Choglontus (SW). A small steam plume rose 100 m and drifted SW the next day. Minor vapor emissions were noted on 11 and 13 August.

Geologic summary: The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. 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. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.

Ongoing activity

CHIRINKOTAN, Kuril Islands 
48.980°N, 153.480°E; summit elev. 724 m

Based on analysis of satellite images, SVERT reported that a thermal anomaly and gas-and-steam emissions from Chirinkotan were observed on 5 and 9 August. A thermal anomaly was visible on 7 August, and possible gas-and-steam emissions were observed on 7 and 8 August. 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 over Snow, a volcano of Chirpoi, was detected in satellite images during 5-7 and 9 August, and possibly during 10-11 August. Steam-and-gas emissions were detected on 9 August. 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.

KILAUEA, Hawaii (USA) 
19.421°N, 155.287°W; summit elev. 1222 m

During 7-13 August HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas. The lake level rose during the week; the level was 49 m below the Halema'uma'u crater floor on 7 August and 37-39 m below the floor during 10-12 August. The level rose to 48 m below the floor during 12-13 August.

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 forest N of Pu'u 'O'o. Peace Day activity, fed by lava tubes extending from Pu'u 'O'o, consisted of some breakout activity on the pali and coastal plain, and an ocean entry outside of the National Park boundary to the E.

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 2-9 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 in satellite images during 2-6 August; cloud cover obscured views on the other days. 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.

PACAYA, Guatemala 
14.381°N, 90.601°W; summit elev. 2552 m

INSIVUMEH reported that during 7-8 August white vapor plumes rose 200 m above Pacaya and drifted E. On 9 August seismicity increased, and Strombolian explosions ejected tephra 200 m above MacKenney Crater and onto the flanks, 400 m away from crater. The next day the number and magnitudes of explosions increased, and seismic signals indicating fluid movement were recorded. Tephra was again ejected 400 m away from MacKenney Crater, causing small avalanches of volcanic material on the flanks. On 12 August fumarolic plumes rose 50 m. Cloud cover prevented observations of the crater on 13 August; however, the seismic network recorded a few gas explosions and tremor.

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 volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 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. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions.

PAVLOF, Alaska Peninsula 
55.42°N, 161.887°W; summit elev. 2519 m

On 8 August AVO reported that no lava or ash emissions had been observed at Pavlof since 26 June and the volcano exhibited gradually declining levels of unrest. Seismicity was at background levels. AVO lowered the Aviation Color Code to Green and the Volcano Alert Level to Normal.

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

REVENTADOR, Ecuador 
0.077°S, 77.656°W; summit elev. 3562 m

IG reported that during 7-8 August explosions at Reventador ejected incandescent material onto the SW flank. Steam emissions were observed on 8 and 9 August, and on 10 August they contained ash and rose 1 km above the crater. Cloud cover prevented observations during 11-13 August; roaring was reported on 13 August.

Geologic summary: Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador 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.

SAKURA-JIMA, Kyushu 
31.585°N, 130.657°E; summit elev. 1117 m

Based on information from JMA, the Tokyo VAAC reported that during 7-11 and 13 August explosions from Sakura-jima generated plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. and drifted SE, S, and NW. On 8, 10 and 13 August pilots observed ash plumes that rose to altitudes of 2.7-3 km (9,000-10,000 ft) a.s.l., and traveled SE, S, and vertically, respectively. JMA reported that seven explosions at Showa Crater were detected during 9-12 August and ejected tephra as far as 800 m. A 50-minute-long eruption on 9 August generated an ash plume that rose 3.5 km above the crater. 

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 two explosions on 7 August from Santa María's Santiaguito lava-dome complex were followed by white plumes that rose 500 m. Pyroclastic material descended the E, S, and SW flanks. Fumarolic plumes rose 100 m on 8 August. On 10 August white plumes rose 250 m. An explosion at 0624 generated an ash plume that rose 900 m and drifted SW, causing ashfall in Monte Claro (S). Heavy rainfall on 11 August caused a lahar in the San Isidro-Tambor River, a tributary of Samala River, which was 30 m wide, 1.5 m thick, and carried branches, tree trunks, and blocks up to 1.5 m in diameter.  A few explosions on 13 August generated ash plumes that rose 1 km and drifted 10 km WSW.

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.

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 2-9 August a viscous lava flow effused on the NW flank of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Satellite images detected a thermal anomaly during 3-6, 8, and 10-11 August. Explosions during 4-5 August generated ash plumes that rose to altitudes of 5-7 km (16,400-23,000 ft) a.s.l. and drifted SSE. A video camera recorded ash plumes that rose to altitudes of 7-7.5 km (23,000-24,600 ft) a.s.l. during 10-11 August. 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.

TOLBACHIK, Central Kamchatka (Russia) 
55.830°N, 160.330°E; summit elev. 3682 m

KVERT reported that the S fissure along the W side of Tolbachinsky Dol, a lava plateau on the SW side of Tolbachik, continued to produce very fluid lava flows during 2-9 August that traveled to the W, S, and E sides of the plateau. Cinder cones continued to grow along the S fissure and weak gas-and-steam plumes were observed. A thermal anomaly on the N part of Tolbachinsky Dol was visible daily in satellite imagery. The Aviation Color Code remained at Orange.

Geologic summary: The massive Tolbachik basaltic volcano is located at the southern end of the dominantly andesitic Kliuchevskaya volcano group. The Tolbachik massif is composed of two overlapping, but morphologically dissimilar volcanoes. The flat-topped Plosky Tolbachik shield volcano with its nested Holocene Hawaiian-type calderas up to 3 km in diameter is located east of the older and higher sharp-topped Ostry Tolbachik stratovolcano. The summit caldera at Plosky Tolbachik was formed in association with major lava effusion about 6500 years ago and simultaneously with a major southward-directed sector collapse of Ostry Tolbachik volcano. Lengthy rift zones extending NE and SSW of the volcano have erupted voluminous basaltic lava flows during the Holocene, with activity during the past two thousand years being confined to the narrow axial zone of the rifts. The 1975-76 eruption originating from the SSW-flank fissure system and the summit was the largest historical basaltic eruption in Kamchatka.

VENIAMINOF, Alaska Peninsula 
56.17°N, 159.38°W; summit elev. 2507 m

AVO reported that during 7-11 August seismicity at Veniaminof remained above background levels. Cloud cover obscured views of the cinder cone inside the caldera during 7-8 August. Slightly elevated surface temperatures, consistent with cooling lava flows, were detected in partly cloudy satellite images during 9-10 August. On 11 August cloud cover prevented satellite image views, and web-camera views showed nothing significant. During 11-12 August seismic tremor increased and persistent elevated surface temperatures, consistent with lava effusion, were visible in satellite imagery. The web camera in Perryville (32 km SSE) recorded intermittent steam-and-ash plumes; one on 12 August rose 3.7 km (12,000 ft) a.s.l. and drifted W. Seismic tremor has remained high on 13 August. 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.

Source: GVP