Active volcanoes in the world from 06/07/2011 to 12/07/2011

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 every Week (mostly 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 of 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 or Unrest

AOBA Vanuatu (SW Pacific) 15.40°S, 167.83°E; summit elev. 1496 m

Lake Voui, Vanuatu - Panoramio image courtesy Dockx Thierry - http://www.panoramio.com/photo/37643095

On 11 July the Vanuatu Geohazards Observatory noted that there had been recent increases in activity from Aoba and that local earthquakes were volcanic. Satellite images collected by the Ozone Monitoring Instrument showed sulfur dioxide emissions. Observations on 4 June revealed that small explosions had been occurring from the crater lake and were accompanied by local ashfall around the crater. Some villagers in the N and W parts of the island had observed the explosions. The Vanuatu Volcano Alert Level (VVAL) remained at 1 (on a scale of 0-4).
Volcano description : Aoba, also known as Ambae, is a massive 2500 cu km basaltic shield volcano that is the most voluminous volcano of the New Hebrides archipelago. A pronounced NE-SW-trending rift zone dotted with scoria cones gives the 16 x 38 km island an elongated form. A broad pyroclastic cone containing three crater lakes is located at the summit of the Hawaiian-style shield volcano within the youngest of at least two nested calderas, the largest of which is 6 km in diameter. Post-caldera explosive eruptions formed the summit craters of Lake Voui (also spelled Vui) and Lake Manaro Ngoru about 360 years ago. A tuff cone was constructed within Lake Voui about 60 years later. The latest known flank eruption, about 300 years ago, destroyed the population of the Nduindui area near the western coast.

ETNA Sicily (Italy) 37.734°N, 15.004°E; summit elev. 3330 m
Sezione di Catania - Osservatorio Etneo reported that explosions from the pit crater located on the E flank of Etna's SE Crater cone were heard on the morning of 4 July. Incandescence was observed later that evening. Small Strombolian eruptions were recorded by a camera during 5-6 July.
On 7 July Strombolian activity gradually increased along with volcanic tremor amplitude. Small pyroclastic cones began to grow on the crater floor. During the next morning, volcanic tremor amplitude clearly increased. Shortly thereafter it abruptly decreased and the Strombolian activity completely ceased. During the morning of 9 July, Strombolian activity resumed and volcanic tremor amplitude rose rapidly. Around noon lava overflowed the E rim of the crater and followed the path of lava flows from the previous eruption, into the upper W part of the Valle del Bove. Later that day Strombolian explosions turned into a continuous lava fountain. A dense eruptive plume rose several kilometers high and drifted S and SE, causing ash and lapilli fall in populated areas including Trecastagni, Viagrande, and Acireale towards the SE, and between Nicolosi and Catania towards the S, forcing the closure of the Fontanarossa international airport in Catania. A few hours later volcanic tremor amplitude dropped to very low levels and all eruptive activity ceased.
Volcano description : 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.
See also our in-depth report including the eruption video recorded on July 9.

IJEN Eastern Java (Indonesia) 8.058°S, 114.242°E; summit elev. 2799 m
The Darwin VAAC reported that on 10 July a pilot observed an ash plume drifting W from Ijen at an altitude of 3.7 km (12,000 ft) a.s.l.
Volcano description : The Ijen volcano complex consists of a group of small stratovolcanoes constructed within the large 20-km-wide Ijen (Kendeng) caldera. The N caldera wall forms a prominent arcuate ridge, but elsewhere the caldera rim is buried by post-caldera volcanoes, including Gunung Merapi stratovolcano, which forms the 2,799 m high point of the Ijen complex. Immediately W of Gunung Merapi is the renowned historically active Kawah Ijen volcano, which contains a nearly 1-km-wide, turquoise-colored, acid crater lake. The picturesque lake is the site of a labor-intensive sulfur mining operation, in which sulfur-laden baskets are hand-carried from the crater floor. A half dozen small-to-moderate phreatic eruptions have taken place from Kawah Ijen during the 20th century.

KATLA Southern Iceland 63.63°N, 19.05°W; summit elev. 1512 m
The Iceland Met Office and news sources reported that on 9 July a jökulhlaup from Myrdalsjökull, the ice sheet that covers Katla, originated from three ice cauldrons in the SE part of the caldera. During previous weeks microseismicity had been registered near several of the ice cauldrons. Around the time of peak harmonic tremor, in the early evening on 8 July, the Myrdalsjökull flood monitoring system indicated increased conduction. The water level reached the bridge around midnight and damaged the sensors. According to news articles, one new cauldron that had formed, along with cracks in the glacier around the cauldrons, may have been caused by a small eruption at Katla although no evidence of an eruption was observed. The jökulhlaup had destroyed a 128-m-long bridge and caused damage, resulting in the closing of part of the Ring Road. About 200 people were evacuated from the area but allowed to return home later that day. On 10 July the water had subsided and returned to normal levels.
Volcano description : Katla volcano, located near the southern end of Iceland's eastern volcanic zone, is hidden beneath the Myrdalsjökull icecap. The subglacial basaltic-to-rhyolitic volcano is one of Iceland's most active and is a frequent producer of damaging jökulhlaups, or glacier-outburst floods. A large 10 x 14 km subglacial caldera with a long axis in a NW-SE direction is up to 750 m deep. Its high point reaches 1380 m, and three major outlet glaciers have breached its rim. Although most historical eruptions have taken place from fissures inside the caldera, the Eldgjá fissure system, which extends about 60 km to the NE from the current ice margin towards Grímsvötn volcano, has been the source of major Holocene eruptions. An eruption from the Eldgjá fissure system about 934 AD produced a voluminous lava flow of about 18 cu km, one of the world's largest known Holocene lava flows. Katla has been the source of frequent subglacial basaltic explosive eruptions that have been among the largest tephra-producers in Iceland during historical time and has also produced numerous dacitic explosive eruptions during the Holocene.
See also our in-depth report including the eruption video recorded on July 9

STROMBOLI Aeolian Islands (Italy) 38.789°N, 15.213°E; summit elev. 924 m
Sezione di Catania - Osservatorio Etneo reported that on 5 July a high pyroclastic jet formed in the S part of Stromboli's crater terrace producing tephra that fell back onto the Pizzo sopra la Fossa. Seismic data indicated that other craters on the terrace were also active. A similar but less powerful explosion occurred from the same vent on 10 July.
Volcano description : Spectacular incandescent nighttime explosions at Stromboli volcano have long attracted visitors to the "Lighthouse of the Mediterranean."Stromboli, the NE-most of the Aeolian Islands, has lent its name to the frequent mild explosive activity that has characterized its eruptions throughout historical time. The small, 926-m-high island of Stromboli is the emergent summit of a volcano that grew in two main eruptive cycles, the last of which formed the western portion of the island. The active summit vents are located at the head of the Sciara del Fuoco, a horseshoe-shaped scarp formed as a result of slope failure that extends to below sea level and funnels pyroclastic ejecta and lava flows to the NW. Essentially continuous mild Strombolian explosions, sometimes accompanied by lava flows, have been recorded at Stromboli since Roman times.

LOKON-EMPUNG Sulawesi 1.358°N, 124.792°E; summit elev. 1580 m
CVGHM reported that during 28 June-9 July white plumes rose 50-400 m above Tompaluan crater, in the saddle between the Lokon-Empung peaks, and gray ash plumes rose 100-500 m above the crater. An ash eruption on 10 July produced white-to-gray plumes that rose 200-400 m above the crater. Fluctuations in the sulfur dioxide gas emission rate were noted during 30 June-10 July. Based on gas flux, seismicity, visual observations, and hazard assessment CVGHM raised the Alert Level to 4 (on a scale of 1-4). On 11 July, the Darwin VAAC reported that ash plumes detected in satellite imagery rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted NW. According to news articles, close to 1,000 residents were evacuated from the area during 11-12 July.
Volcano description : 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-dome growth and pyroclastic flows have also occurred.
http://www.vsi.esdm.go.id/
See also our in-depth report including the eruption video recorded on July 11

PUYEHUE-CORDON CAULLE Central Chile 40.590°S, 72.117°W; summit elev. 2236 m
OVDAS-SERNAGEOMIN reported that during 6-8 July cameras installed around the Puyehue-Cordón Caulle volcanic complex recorded eruption plumes that rose no higher than 2 km above the Cordón Caulle rift zone and drifted N and NE. On 6 July satellite imagery indicated that the plume drifted 75 km NE. During 7-8 July explosions recorded by the seismic network corresponded to increases in the plume height and, on 7 July, caused windows in Riñinahue to vibrate. According to news articles, numerous flights in and around Argentina and Uruguay were cancelled on 8 July and some airports had remained closed.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/
See also our extensive reporting in Earthquake-report.com
For the list of volcanoes with Ongoing activity, please click here

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