This week, 6 volcanoes were noticed to have new activity, whereas ongoing activity was reported for 11 volcanoes. This report covers active volcanoes in the world recorded from January 30 – February 5, 2013 based on Smithsonian/USGS criteria.
New activity/unrest: | Colima, México | Etna, Sicily (Italy) | Paluweh, Lesser Sunda Islands (Indonesia) |Rabaul, New Britain | Reventador, Ecuador | White Island, New Zealand
Ongoing activity: | Batu Tara, Komba Island (Indonesia) | Chirpoi, Kuril Islands (Russia) | Copahue, Central Chile-Argentina border | Karymsky, Eastern Kamchatka (Russia) | Kilauea, Hawaii (USA) |Kizimen, Eastern Kamchatka (Russia) | Lokon-Empung, Sulawesi | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) | Tolbachik, Central 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 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.
19.514°N, 103.62°W; summit elev. 3850 m
Based on analyses of satellite imagery, the Washington VAAC reported that on 29 January an ash plume from Colima drifted 55 km NE at an uncertain altitude. A thermal anomaly was also detected.
According to news articles, residents up to 20 km away reported a loud noise, shaking ground, and rattling windows at about 0400 on 29 January. Colima ejected incandescent material and an ash plume that rose 3 km. Ash fell in several communities.
Geologic summary: The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcán de Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequenthistorical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth.
ETNA, Sicily (Italy)
37.734°N, 15.004°E; summit elev. 3330 m
Sezione di Catania – Osservatorio Etneo reported that intense Strombolian activity at Etna’s Bocca Nuova Crater began on the evening of 30 January and was the fifth episode of activity during a three-week interval that began on 10 January. Weak glow from a vent on the SE part of the crater floor was first observed at 1807. The glow became stronger and was visible to nearby residents; simultaneously volcanic tremor amplitude rapidly increased, and shifted from below the New Southeast Crater (NSEC) toward Bocca Nuova. Between 1900 and 1915 the activity intensified, and from 1920 onward jets of incandescent volcanic bombs and scoria nearly continuously rose higher than the crater rim. Some tephra was ejected 150 m above the rim.
During 1930-2000, lava fountains rose 100 m above the rim. Shortly after 2000, the fountain leaned SW and produced heavy fallout of incandescent bombs and scoria on the outer SW flank of the central summit cone, down to its base. At 2016 the fountain rose vertically and pyroclastic fallout outside the crater diminished.
Around 2030 the lava fountain started to wane; the incandescent jets became discontinuous and only rarely rose more than 100 m above the crater rim, except for one jet, at 2100, which rose 150 m above the rim. In addition, the volcanic tremor amplitude rapidly decreased and returned to normal levels in the late evening. After 2200, the incandescent pyroclastic jets no longer rose above the crater rim, and the glow became progressively less brilliant. During the night, however, weak eruptive activity continued on the crater floor, evident from a dull glow emanating from the crater. During the early morning hours of 31 January, the glow gradually faded away, and the episode ended with a series of sporadic, small ash emissions, the last of which was seen around 0641.
During 31 January-1 February ash emissions at New Southeast Crater (NSEC) were nearly continuous for intervals lasting from a few minutes to more than one hour. On 1 February small discrete “puffs” of ash rose from Bocca Nuova. At both craters ash plumes rose no higher than 100 m above the crater rims.
At 0300 on 2 February a camera recorded weak glow from NSEC then after 0330 sporadic small explosions ejected incandescent pyroclastic material up to a few tens of meters above the crater rim. The strongest explosions (at 0345, 0400, 0409, and 0411) ejected glowing bombs onto the flanks of the NSEC cone. Two minutes after the last of the explosions, weak glow appeared at Bocca Nuova that only lasted a short time; during the following 30 minutes, however, intermittent glow was recorded at both craters. At 0450 jets of lava rose above the rim of Bocca Nuova; at 0500 Strombolian activity became continuous, producing jest that rose many tens of meters above the rim. Small Strombolian explosions resumed in NSCE at 0512. Just after 0515 activity at Bocca Nuova started to increase rapidly; contemporaneously, the volcanic tremor amplitude showed a sharp rise. Lava fountains rose 120-150 m above the rim. Activity at NSEC started to decrease at 0530 then ceased just before 0600. Activity at Bocca Nuova decreased markedly between 0620 and 0630; weak intracrater activity continued for a few more hours and then by 0900 the episode was over.
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 BC. Historical lava flows cover much of the surface of this massive basaltic stratovolcano, the highest and most voluminous in Italy. 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. Flank eruptions, typically with higher effusion rates, occur less frequently and originate from fissures that open progressively downward from near the summit. A period of more intense intermittent explosive eruptions from Etna’s summit craters began in 1995. The active volcano is monitored by the Instituto Nazionale di Geofisica e Volcanologia (INGV) in Catania.
PALUWEH, Lesser Sunda Islands (Indonesia)
8.32°S, 121.708°E; summit elev. 875 m
According to news articles, an explosion from Paluweh occurred at 2300 on 2 February and was clearly heard by local residents. Authorities evacuated by boat all residents from the eight villages on the island. Ashfall was reported during 2-3 February.
Based on analyses of satellite imagery, wind data, and pilot reports, the Darwin VAAC reported that on 3 Februaryash plumes from Paluweh rose to altitudes of 13.1-13.7 km (43,000-45,000 ft) a.s.l. and drifted 325-590 km SE, S, and SW. Elevated levels of sulfur dioxide were also detected. The next day ash plumes at an altitude of 7.6 km (25,000 ft) a.s.l. were observed.
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.
RABAUL, New Britain
4.271°S, 152.203°E; summit elev. 688 m
According to a news report from 31 January, Tokua airport (20 km SE) reopened after being closed due to ash from Rabaul.
RVO reported that during 1-3 February Rabaul was mostly quiet, although occasional explosions produced light gray ash plumes that rose as high as 500 m above sea level and drifted E and ESE. At 1151 on 3 February an explosion produced a dense, dark ash plume that slowly rose 2 km above sea level and drifted ENE. Ash was observed falling on South Daughter (Turangunan, ~2 km to the E) and to the N of it. Dark gray ash emissions continued for the next 15-20 minutes. During the afternoon of 3 February through the morning of 4 February light gray ash emissions rose at irregular intervals and drifted E and ESE. White vapor plumes rose from the crater in between the ash emissions.
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.
0.077°S, 77.656°W; summit elev. 3562 m
During an overflight of Reventador on 29 January scientists observed an explosion and a steam-and-ash plume that rose 1.5 km above the lava dome. Since November the dome had significantly grown to at least 100 m higher than the E rim, and about 20 lava flows had traveled down the N, SE, and S flanks.
During 29 January-5 February seismicity remained high. Cloud cover often prevented observations although emissions were observed; steam-and-ash plumes rose 2-4 km and drifted W and NW on most days. Crater incandescence was observed at night during 29-30 January.
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.
WHITE ISLAND, New Zealand
37.52°S, 177.18°E; summit elev. 321 m
On 30 January GeoNet Data Centre reported that White Island’s “hot lake” had dried up and a small tuff cone was forming on the former floor of the lake. The active vent continued to eject bursts of mud, rock, steam, and gas 50-100 m high. This activity along with the seismic activity was intermittent. Gas measurements taken during an overflight showed that the levels of volcanic gases emitted from the volcano were slightly higher than the levels measured the previous week: carbon dioxide gas flux increased from 1,800 to 2,000 tons/day, sulfur dioxide flux increased from 366 to 600 tons/day, and hydrogen sulfide flux was 19 tons/day (previously 15 tons/day). During 30-31 January seismicity changed to continuous tremor and remained at a high level. The Aviation Colour Code remained at Orange (second highest on a four-color scale) and the Volcanic Alert Level remained at 1 (on a scale of 0-5).
Geologic summary: The uninhabited 2 x 2.4 km White Island, one of New Zealand’s most active volcanoes, is the emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The 321-m-high island consists of two overlapping stratovolcanoes; the summit crater appears to be breached to the SE because the shoreline corresponds to the level of several notches in the SE crater wall. Throughout the shorthistorical period beginning in 1826 the volcano has had long periods of continuous hydrothermal activity and steam release, punctuated by small-to-medium eruptions. Its activity also forms a prominent part of Maori legends. The most recent eruptive episode, which began on 7 March 2000, included the largest eruption at White Island in the past 20 years on 27 July.
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 on 29 January ash plumes from Batu Tara rose to an altitude of 1.8 km (6,000 ft) a.s.l. and drifted E. Ash plumes rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted over 110 km W on 4 February and 55 km W on 5 February.
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 historicaleruption from Batu Tara, during 1847-52, produced explosions and a lava flow.
CHIRPOI, Kuril Islands (Russia)
46.525°N, 150.875°E; summit elev. 742 m
SVERT reported that steam-and-gas emissions from Snow, a volcano of Chirpoi, were detected in satellite images on 1 February; cloud cover prevented observations of the volcano on other days during 28 January-4 February.
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 thecaldera 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 oflava 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.
COPAHUE, Central Chile-Argentina border
37.85°S, 71.17°W; summit elev. 2997 m
OVDAS-SERNAGEOMIN reported that during 29 January-4 February the web camera near Copahue recorded white gas plumes rising 350-1,550 m above the crater and drifting E and SE. Seismicity fluctuated but mostly remained at low levels. The Alert Level was lowered to Yellow on 4 February.
The Buenos Aires VAAC noted that although a pilot reported an ash plume between the altitudes of 3-4.6 km (10,000-15,000 ft) a.s.l., no ash was detected in mostly clear satellite images. The VAAC also noted that steam with possible diffuse ash was recorded by the OVDAS webcam.
Geologic summary: Volcán Copahue is an elongated composite cone constructed along the Chile-Argentina border within the 6.5 x 8.5 km wide Trapa-Trapa caldera that formed between 0.6 and 0.4 million years ago near the NW margin of the 20 x 15 km Pliocene Caviahue (Del Agrio) caldera. The eastern summit crater, part of a 2-km-long, ENE-WSW line of nine craters, contains a briny, acidic 300-m-wide crater lake (also referred to as El Agrio or Del Agrio) and displays intense fumarolic activity. Acidic hot springs occur below the eastern outlet of the crater lake, contributing to the acidity of the Río Agrio, and another geothermal zone is located within Caviahue caldera about 7 km NE of the summit. Infrequent mild-to-moderate explosive eruptions have been recorded at Copahue since the 18th century. Twentieth-century eruptions from the crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.
KARYMSKY, Eastern Kamchatka (Russia)
54.05°N, 159.45°E; summit elev. 1536 m
KVERT reported that weak seismic activity at Karymsky was detected during 25 January-1 February. Satellite imagery showed a thermal anomaly on the volcano during 24-25 and 30 January. The Aviation Color Coderemained at Orange.
Based on information from the Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 30 January an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted SE. An ash plume was not detected in satellite imagery.
Geologic summary: Karymsky, the most active volcano of Kamchatka’s eastern volcanic zone, is a symmetricalstratovolcano 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.
KILAUEA, Hawaii (USA)
19.421°N, 155.287°W; summit elev. 1222 m
During 30 January-5 February HVO reported that the circulating lava lake periodically 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 was 32 m below the Halema’uma’u crater floor on 31 January.
At Pu’u ‘O’o Crater, glow emanated from spatter cones on the SE part of the crater floor, from a spatter cone at the NW edge of the floor, and from a perched circulating lava lake on the NE part of the floor. Lava flows were active in a 1-km-wide area on the coastal plain. Web cameras recorded steam plumes from lava sporadically entering the ocean at multiple locations. Lava from the lava lake (perched 5-6 m higher than the crater rim) flowed across the NE flank of Pu’u ‘O’o cone to the cone’s base and continued to advance over older flows. On 31 January the N spatter cone gushed with lava; the flow quickly banked against the N crater wall, advanced E to the base of the perched pond at the NE edge, and W towards the W crater wall. On 4 February a minor amount of lava flowed out of the SW spatter cone, and a brief but voluminous lava flow gushed out of the NW spatter cone on 5 February.
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 25 January-1 February moderate seismic activity continued at Kizimen. Video data showed that lava continued to extrude from the summit onto the E and SE flanks. Summit incandescence, strong gas-and-steam activity, and occasional hot avalanches on the W and E flanks accompanied the process. Satellite images detected a daily thermal anomaly over the volcano. 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.
1.358°N, 124.792°E; summit elev. 1580 m
According to news articles, Lokon-Empung erupted twice on 31 January, producing an ash plume that rose 800 m after the first eruption. Seismicity had increased the day before. In another article the head of the Lokon observation post reported that eruptions from Lokon occurred daily, and specifically that nine eruptions had occurred on 2 February.
Based on a ground report from CVGHM, the Darwin VAAC reported that an ash plume from Lokon-Empung rose to an altitude of 4 km (13,000 ft) a.s.l. on 3 February. Ash was not detected in satellite imagery.
Geologic summary: The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2.2 km apart) has a flat, craterless top. The morphologically younger Empung volcano has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-domegrowth and pyroclastic flows have also occurred.
31.585°N, 130.657°E; summit elev. 1117 m
JMA reported that during 28 January-1 February explosions from Sakura-jima’s Showa Crater ejected tephra as far as 1.8 km from the crater. Crater incandescence was occasionally detected.
The Tokyo VAAC reported that pilots observed ash plumes at altitudes of 3 km (10,000 ft) a.s.l. during 30-31 January. Based on information from JMA, explosions during 31 January-5 February generated plumes on most days that rose to altitudes of 1.8-3 km (6,000-10,000 ft) a.s.l. and drifted N, NW, and SE.
Geologic summary: Sakura-jima, one of Japan’s most active volcanoes, is a post-caldera cone of the Aira calderaat 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 depositedash 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
On 30 January, INSIVUMEH reported that both an increasing height of ash plumes from explosions at Santiaguitolava-dome complex and a change in wind direction caused ashfall in the towns of Esperanza and San Mateo in Quetzaltenango. Dark gray plumes rose an average of 800 m above the complex and were accompanied by sulfur dioxide emissions.
During 30-31 January a series of small explosions produced ash plumes that rose 300 m and drifted NW. Activelava flows produced avalanches. During 31 January-1 February ashfall was reported in areas to the S. Two explosions on 3 February generated ash plumes that rose 700 m above the complex and drifted SW. Noise from avalanches were reported on 4 February. Two explosions on 5 February generated white-and-gray plumes that rose 700 m and drifted SW, causing ashfall in areas downwind.
Geologic summary: Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoesthat 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 periodiclava 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 25 January-1 February a viscous lava flow effused on the E flank of Shiveluch’s lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Satellite imagery showed a daily thermal anomaly on the lava dome. The Aviation Color Coderemained 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 25 January-1 February that traveled to the W and S sides of Tolbachinsky Dol. Four cinder cones continued to grow on the S fissure above Krasny cone. Gas-and-ash plumes rose to an altitude of 3.5 km (11,500 ft) a.s.l. and drifted in multiple directions. A very large 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 dominantlyandesitic 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-typecalderas 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.
Source: Global Volcanism Program
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