Active volcanoes in the world: July 17 – July 23, 2013

This week, 6 volcanoes had new activity,  ongoing activity was reported for 9 volcanoes. This report covers active volcanoes in the world recorded from July 17 – July 23, 2013 based on Smithsonian/USGS criteria.

New activity/unrest: | Merapi, Central Java (Indonesia) | Popocatépetl, México | Shiveluch, Central Kamchatka (Russia) | Tungurahua, Ecuador | Turrialba, Costa Rica | Ulawun, New Britain

Ongoing activity: | Chirinkotan, Kuril Islands | Kilauea, Hawaii (USA) | Kizimen, Eastern Kamchatka (Russia) | Manam, Northeast of New Guinea (SW Pacific) | Rabaul, New Britain | 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

MERAPI, Central Java (Indonesia) 
7.542°S, 110.442°E; summit elev. 2968 m

Balai Penyelidikan dan Pengembangan Teknologi Kegunungapian (BPPTK) reported that at 0415 on 22 July a booming sound from Merapi was followed by a rising plume observed from multiple observation posts. Ashfall was reported in areas S, including Kaliurang and Balerante. The Alert Level remained at 1 (on a scale from 0-4).

According to news articles, the eruption lasted until about 0530, and generated a dense black plume that rose 1 km. A booming sound was heard 30 km away. Ashfall affected the district of Deles, Tlogowatu, Kemalang, Balerante, Klaten, and Jawa Tengah. Hundreds of residents evacuated but returned to their homes later that day.

Geologic summary: Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately N of the major city of Yogyakarta. The steep-sided modern Merapi edifice, its upper part unvegetated due to frequent eruptive activity, was constructed to the SW of an arcuate scarp cutting the eroded older Batulawang volcano. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated and inhabited lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory (MVO).

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

CENAPRED reported that during 17-23 July seismicity at Popocatépetl indicated continuing gas-and-steam emissions that sometimes contained ash; cloud cover often prevented visual confirmation. Incandescence from the crater was occasionally observed. On 17 July an explosion was detected at 1516. During a period of clear weather on 19 July observers noted steam-and-gas plumes drifting W. An explosion at 1533 generated a steam, gas, and ash plume that rose 700 m above the crater and drifted NW. Another explosion was detected at 2257. On 20 July steam-and-gas plumes rose 1 km and drifted SW; steam, gas, and ash emissions rose 1.2 km and drifted WSW. Steam-and-gas plumes were bluish on 21 July; the plumes rose 500 m and drifted NW. An explosion at 0343 on 23 July generated an ash plume that rose 1.1 km and drifted NW. The Alert Level remained at to Yellow, Phase Three.

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 12-19 July a viscous lava flow effused on the N flank of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, and fumarolic activity. Based on notices from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 15 July an ash plume rose to an altitude of 4.6 km (15,000 ft) a.s.l. and drifted E.  KVERT noted that satellite images detected a thermal anomaly on 15, 17, and 18 July; cloud cover prevented observations on the other days. 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 at night during 16-17 July observers noted incandescent blocks falling onto Tungurahua's flanks. Cloud cover often prevented observations. An explosion was heard in Ambato (31 km N) on 16 July. Explosions were detected on 17 July, and white ashfall was reported in Choglontus (SW). Steam-and-ash plumes were observed rising 1.5 km and drifting W. During 18-19 July Strombolian activity ejected blocks that rolled 500 m down the flanks. Ash fell in Choglontus. Seismicity remained high during 17-19 July; 18-33 long-period earthquakes, 53-82 tremors indicting emissions, and 3-6 explosions were recorded per day.

On 19 July an ash plume rose 1 km and drifted SW. The geodetic monitoring system indicated an inflationary trend on the N flank and deflation SW of the volcano, indicating the presence of a magma body about 2 km below the crater. During 19-20 July ashfall was reported in Choglontus and El Manzano (8 km SW). On 20 July 127 long-period earthquakes, 71 tremors indicting emissions, and 43 explosions were detected.

Seismicity again increased on 21 July; 220 long-period earthquakes, three periods of tremor indicating emissions, and 15 explosions were detected. The three periods of tremor were characterized by two 1-hour-long sessions and a third period lasting at least eight hours. Explosions vibrated nearby structures, and ejected blocks onto the upper parts of the flanks. Gas-and-ash plumes rose as high as 5 km, and produced ashfall in Cevallos (23 km NW), Tisaleo (29 km NW), Mapayacu (SW), Choglontus, and El Manzano. Strombolian activity overnight during 21-22 July ejected blocks that rolled 500 m down the flanks. Strong explosions again vibrated structures, and ash emissions rose 1 km. Ashfall was noted in El Manzano, Pillate, Chacuaco and Cahuaji. On 23 July ash plumes rose 1.5 km and drifted WSW. Strombolian activity was observed overnight and roaring was heard. Ashfall was reported in Cahuají and Choglontus. Seimscity decreased but still remained high during 22-23 July; 22-40 long-period earthquakes, 7-12 tremors indicting emissions, and 4-9 explosions were detected per day.

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.

TURRIALBA, Costa Rica
10.025°N, 83.767°W; summit elev. 3340 m

OVSICORI-UNA reported significant seismic activity at Turrialba starting on 14 July. Low-frequency signals indicating fluid movement grew from an average of less than 200 events per day to over 600 events on 14 July, reaching a peak of activity with over 1,000 events on 15 July. Low-frequency tremor was detected during 18-19 July. Elevated seismicity remained at least through the report posting on 20 July. No morphological changes at the surface were observed.

Geologic summary: Turrialba, the easternmost of Costa Rica's Holocene volcanoes, is a large vegetated basaltic-to-dacitic stratovolcano located across a broad saddle NE of Irazú volcano overlooking the city of Cartago. The massive 3340-m-high Turrialba is exceeded in height only by Irazú, covers an area of 500 sq km, and is one of Costa Rica's most voluminous volcanoes. Three well-defined craters occur at the upper SW end of a broad 800 x 2200 m wide summit depression that is breached to the NE. Most activity at Turrialba originated from the summit vent complex, but two pyroclastic cones are located on the SW flank. Five major explosive eruptions have occurred at Turrialba during the past 3500 years. Turrialba has been quiescent since a series of explosive eruptions during the 19th century that were sometimes accompanied by pyroclastic flows. Fumarolic activity continues at the central and SW summit craters.

ULAWUN, New Britain
5.05°S, 151.33°E; summit elev. 2334 m

RVO reported that activity at Ulawun was low during 15-21 July. Emissions from the summit crater were light gray during 15-16 July, and then changed to white vapor during 17-21 July. RSAM from volcanic tremors had increased on 14 July and reached a peak of 700 just after 0300 on 15 July. RSAM then decreased to 80 on 21 July, which also marked the cessation of volcanic tremors.

Geologic summary: The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.

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 possible weak steam-and-gas emissions from Chirinkotan were observed on 16 and 18 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.

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

During 17-23 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. On 19 July several pieces of the pit wall fell into the lake.

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 N as 2.6 km and as far NNW as 1.9 km, and burned forest in both areas. 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 at a location E and outside of the National Park boundary.

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 12-19 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 15-18 July. 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 activity at Manam’s Main and Southern craters was low. White vapor plumes were observed rising from both craters when weather conditions were clear. 

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.

RABAUL, New Britain
4.271°S, 152.203°E; summit elev. 688 m

RVO reported that during 15-21 July low-level activity consisted of discrete emissions of pale gray ash plumes occurring at short intervals. Some emissions were explosive and generated plumes that rose 2 km above the crater. Plumes drifted E, NE, N, NW, W, and SW, and deposited minor amounts of ash in areas downwind mainly between Nodup and Rapolo (with Rabaul Town, 3-5 km NW, in between), and to a lesser extent in the Vulcan area. Roaring and rumbling noises also continued, often in conjunction with explosions.

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.

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

IG reported that during 17-19 July seismic activity at Reventador remained high; at times periods of increased seismicity were followed by relatively quiet episodes. The seismic network recorded long-period signals, rockfalls, explosions, and emissions. Based on reports from observers at camp San Rafael,   cloud cover often prevented visual observations, although on 18 July a new lava flow on the E flank was observed with a video camera, and a gas-and-ash plume was observed rising 1 km. During 21-22 July gas plumes with low ash content rose to low heights.

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
1.585°N, 130.657°E; summit elev. 1117 m

JMA reported that five explosions at Sakura-jima's Showa Crater were detected during 16-19 July, and ejected tephra as far as 1.3 km. A large plume rose 3.5 km above the crater on 16 July.  Incandescence from the crater was observed at night during 18-19 July. Based on information from JMA, the Tokyo VAAC reported that during 18-21 July explosions generated plumes that rose to altitudes of 2.4-4.3 km (8,000-14,000 ft) a.s.l. and drifted N, E, SE, and S. Ash was sometimes detected in satellite images. On 19 July a pilot observed an ash plume that rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted 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 12-19 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 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 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 emission of minor amounts of ash and steam, continued during 17-23 July, indicated by nearly continuous 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. The web camera in Perryville (32 km SSE) recorded nighttime incandescence and low-level ash-and-steam plumes during 22-23 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