Active volcanoes in the world: July 24 – July 30, 2013

This week, 7 volcanoes had new activity,  ongoing activity was reported for 9 volcanoes. This report covers active volcanoes in the world recorded from July 24 – July 30, 2013 based on Smithsonian/USGS criteria.

New activity/unrest: | Ambrym, Vanuatu (SW Pacific) | Karangetang [Api Siau], Siau | Ketoi, Kuril Islands (Russia) | Popocatépetl, México | Shiveluch, Central Kamchatka (Russia) | Tungurahua, Ecuador | White Island, New Zealand

Ongoing activity: | Chirinkotan, Kuril Islands | Chirpoi, Kuril Islands (Russia) | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Pacaya, Guatemala | Reventador, Ecuador | Sakura-jima, Kyushu | 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

AMBRYM, Vanuatu (SW Pacific) 
16.25°S, 168.12°E; summit elev. 1334 m

The Vanuatu Geohazards Observatory reported that activity at Ambrym slightly increased to a minor eruptive phase, and a seismic swarm was detected between 2400 and 0700 on 26 July. The Alert Level remained at 1 (on a scale of 0-4).

Geologic summary: Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major Plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.

KARANGETANG, [API SIAU] Siau I 
2.78°N, 125.40°E; summit elev. 1784 m

Based on reports from the observation post in Salili, CVGHM stated on 26 July that the occurrence of rock avalanches descending Karangetang’s flanks decreased during 2013; the last one occurred on 7 July, and traveled 2 km down the Batuawang and Kahetang (E) drainages. Although fog often prevented visual observations, white plumes were sometimes seen rising up to 500 m from two craters. Incandescence from the lava dome was reflected in the plume at night. Seismicity fluctuated, but signals indicating avalanches declined. Based on the cessation of avalanches, visual observations, and decreasing seismicity, the Alert Level was lowered to 2 (on a scale of 1-4) on 26 July.

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.

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

SVERT reported that on 25 July a thermal anomaly from Ketoi's Pallas Peak was observed in satellite imagery along with gas-and-steam emissions drifting 100 km NW. On 27 July gas-and-steam emissions possibly containing ash drifted 45 km SSE.

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.

POPOCATEPETL, México
19.023°N, 98.622°W; summit elev. 5426 m

CENAPRED reported that on 23 July the Coordinación Nacional de Protección Civil (CNPC) of the Secretaría de Gobernación (SEGOB), CENAPRED, and a Scientific Advisory Committee lowered the Alert Level at Popocatépetl to Yellow, Phase Two. Access to the crater within a 12-km radius was prohibited.

During 24-30 July seismicity indicated continuing gas-and-steam emissions that sometimes contained ash; cloud cover often prevented visual confirmation. During 24-27 July often continuous plumes rose 200 m above the crater and drifted W, NW, and SW. Incandescence from the crater was observed most nights. Ash in the emissions was observed during 26-27 July. At 1237 and 1917 on 28 July, and 0733 on 29 July, ash plumes rose as high as 2 km and drifted W.

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 19-26 July a viscous lava flow effused on the N flank of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Satellite images detected a daily thermal anomaly. Based on analyses of satellite images, the Tokyo VAAC reported a possible eruption on 27 July. Ash was detected in images the next day. The VAAC also noted that, according to the Kamchatka Branch of Geophysical Services (KBGS; Russian Academy of Sciences), ash plumes rose to altitudes of 6.1-6.4 km (20,000-21,000 ft) a.s.l. on 27 and 29 July. KVERT reported that at 1317 on 29 July an explosion was observed by a web camera. An ash cloud detected in satellite images rose to an altitude of 3.5 km (11,500 ft) a.s.l. and drifted 60 km ESE; the cloud was 15 km long and 7 km wide. 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.

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

IG reported that activity at Tungurahua remained high during 24-30 July. Although cloud cover often prevented visual observations of the crater, plumes were observed almost daily. Roaring was also regularly reported. On 24 July an ash plume rose 5 km above the crater and drifted WNW, causing black ashfall in El Manzano (8 km SW), Choglontus (SW), Puela (8 km SW), Cahuají (8 km SW), and minor ashfall in Cevallos (23 km NW), Quero (20 km NW), and Mocha (25 km WNW). On 25 July ashfall was reported in El Manzano, Choglontus, and Cahuají. An explosion at 1835 generated an ash plume that rose 2 km and drifted W. The next day windows vibrated at the Tungurahua Observatory (OVT) in Guadalupe (14 km N). Minor amounts of ash fell in El Manzano, Choglontus, Puela, Mocha, and in the sectors of Guaranda (65 km WSW), Salinas, and Guanujo (65 km WSW). Overnight during 26-27 July Strombolian activity ejected blocks that rolled 300 m down the flanks. At 1947 a strong explosion vibrated windows at OVT and in El Manzano and Pillate (8 km W). An ash plume rose 2 km and drifted WSW; minor ashfall was reported in Bilbao (W), Quero, and Mocha. Later that day ash emissions rose 500 m and drifted SW.

Activity increased on 28 July; at 0626 a higher number of long-period earthquakes were detected, explosions became more frequent and larger, blocks were ejected, and ash emission rose from the crater. An explosion at 0723 generated a small pyroclastic flow that descended the N flank. Ash fell in Choglontus, El Manzano, Mocha, and Tisaleo (29 km NW). Activity remained high the next day; ash plumes rose 2 km and drifted WNW. During 28-29 July and ashfall was reported in Mocha, Quero, Tisaleo, Cevallos, and Pillate.

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.

WHITE ISLAND, New Zealand 
37.52°S, 177.18°E; summit elev. 321 m

GeoNet Data Centre reported that volcanic tremor levels at White Island increased overnight during 25-26 July; the increased seismicity and images of activity on web cameras prompted volcanologists to visit the volcano on 26 July. They noted audible jets of gas venting through the small lake, broader expanding “bubbles” of dark lake sediments, and debris ejected 20-30 m vertically. The Volcano Alert Level remained at 1 (on a scale of 0-5) and the Aviation Colour Code was increased to Yellow (on a four-color scale).

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 short historical 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.

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 from Chirinkotan was observed on 22 July. Weak steam-and-gas emissions and a weak thermal anomaly were observed on 25 July. 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 possible steam-and-gas emissions from Snow, a volcano of Chirpoi, were detected in satellite images on 23 July. 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 24-30 July 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 receded during 25-26 July and was 75 km below the Halema'uma'u Crater floor on 26 July. The inner ledge, a long-time fixture within the vent, started collapsing at 2030 on 25 July; several pieces of the pit wall fell into the lake on both days. The lake level started to rise again and was 65 and 67 m below the crater floor on 28 and 29 July, respectively.

At Pu'u 'O'o Crater, glow emanated from three spatter cones and a small lava pond on the E part of the crater floor. The Kahauale’a 2 lava flow branches, fed by the NE spatter cone, were active as far NE as 3.2 km and as far NW as 2 km, and burned forest in two locations at the N edge of the 1983-1986 'a'a flows from 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 19-26 July 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 19-20 and 23 July; 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

In a special bulletin on 24 July, INSIVUMEH noted that the eruption at Pacaya had been changing during the previous few days, especially the seismic pattern. Seismic signals indicating explosions and ejections of material lasted up to seven minutes; the events were low frequency and long duration. The cone continued to grow and was 30 m high earlier in the week. By 24 July the cone was 4 m above the MacKenney crater rim. Seismicity again increased. On 25 July weak explosions and incandescence from the cone were observed at night. Rumbling was heard. On 29 July incandescence from the crater was observed for a few hours in the morning, and a plume rose at most 100 m and drifted S. An eruption on 30 July included a high-energy phase that lasted for four hours and incandescent material that was ejected 250 m above the cone. A diffuse ash plume drifted 2 km N, causing ashfall in areas downwind, and another ash plume drifted 5 km S. Activity then declined considerably; explosions were not observed and seismicity decreased, although signals indicating fluid movement continued to be detected. 

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.

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

IG reported that during 24-30 July seismic activity at Reventador remained high and was characterized by explosions, low-intensity emissions, and long-period earthquakes indicting fluid movement. Cloud cover mostly prevented visual observations. On 26 July an explosions generated a low-altitude ash plume that drifted W.

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

JMA reported that 10 explosions at Sakura-jima's Showa Crater were detected during 22-26 July, and ejected tephra as far as 1.3 km. Explosions at 1635 and 2333 on 22 July generated ash plumes that rose 3.2 and 3 km above the crater rim, respectively. Based on information from JMA, the Tokyo VAAC reported that during 24-30 July explosions generated plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted E and SE. During 24-27 and 29 July pilots observed ash plumes that rose to altitudes of 2.7-5.5 km (9,000-18,000 ft) a.s.l. and drifted E and SE.

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.

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 19-26 July 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 the ongoing low-level eruption of Veniaminof, characterized by lava effusion and emissions of minor amounts of ash and steam, continued during 24-30 July, indicated by fluctuating volcanic tremor and occasional small explosions detected by the seismic network. On most days satellite images showed elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. On 25 July a pilot reported an ash plume that rose 60-100 m above the cone and drifted almost 25 km S, and a "river of lava" flowing down from the cone. On 27 July a pilot observed an ash emission that rose 300-600 m and drifted NW. A water-rich plume likely containing minor amounts of ash was detected in satellite images drifting NW at an altitude of 4.5 km (15,000 ft) a.s.l. on 29 July. 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