As the National Institute of Geophysics and Volcanology reports, an increased number of small to medium earthquakes have occurred lately at Etna volcano, the largest one being today (Sun, 30 Oct. 05) at 3.7 magnitude Richter at 08h06 on the southeastern slopes near Pedara, Trecastagni et Nicolosi. Etna has been without eruptive activity since March 2005; new eruptions are expected within a near to medium future (months or few years, possibly less if the recent seismic activity is taken as possible precursor).
The eruption of Sierra Negre continues with lava flows confined to the vast caldera; it does not pose risks to populated areas. In the meanwhile, a group of scientists from the Geophysical Institute of Ecuador have visited the site and posted a detailed report about the eruption's first 3 days: it can be downloaded here.
Eruption of Sierra Negre volcano on 25 Oct. 2005 (Photo: Jorge Penafiel / El Universo)
The eruption is continuing from a fissure inside the E part of the caldera of Sierra Negre, with lava fountains up to 200 m tall and large lava flows that have now covered about 20% of the caldera floor. Good eruption viewing possibilities are from a lookout on the caldera rim in the El Cura area.
Eruption plume of the opening phase of Sierra Negra volcano on 23 Oct. 2005 (photo: Greg Arancea, published on "El Universo" newspaper)
Lava fountains at Sierra Negra volcano (photo AP /APTN on "El Universo")
First photographs and more detailed information about the large eruption of Sierra Negre are emerging. As on Monday, 24 October, lava flows from a fissure have travelled 9-10 km away from the fissure. The eruption is accompanied by strong lava fountains. Near the eruption site, the terrain consists mainly of older, unvegetated lava flows. Two flows are travelling towards Elizabeth Bay, while a third one is heading towards Cartago Bay, both uninhabited areas. The popoluation of Puerto Villamil is not threatened because of its sheltered position at the S of the island.
--- Backgound: Sierra Negre is the largest of the Galapagos volcanoes, with a caldera 10 km in diameter. Its last eruptino occurred in 1979; the lava flows of that eruption did not pose any significant risk to the population of the island.
Sierra Negra volcano, also called "El Chico", on Isabela Island, Galapagos, erupted yesterday at 17h30 local time. As the Ecuadorian newspaper "El Universo" reports, an ash column estimated between 20 to 30 km high was observed. According witnesses from Santa Cruz island, two lava flows reached Elizabeth Bay, an uninhabitated settlement area close to the volcano. The island's main town, Puerto Villamil, 25 kilometers (15 miles) away, is not threatened by the eruption. Sierra Negro last erupted 1978.
A team of scientists visited the Da'Ure locality immediately adjacent to the NE flank of the Quaternary Dabbahu (or Boina) felsic complex on 4 and 5 October after receiving reports of volcanic activity there on 26 September. People in the area noted that on 26 September at about 1300 a very strong earthquake shook the area, and was followed by a dark column of "smoke" that rose high into the atmosphere and spread out to form a cloud, which darkened the area for 3 days and 3 nights. The scientists determined that a minor explosive eruption occurred from two semi-circular vents, producing ashfall that was ~5 cm thick near the vent. Ash deposits extended more than 500 m from the vent. Boulders emitted during the eruption were as large as 3 m and were deposited as far as 20 meters away. The scientists noted intense degassing from the vents, the scent of sulfur dioxide, and the sound of boiling water in the vents. As of about 10 October, the Addis Ababa University Geophysical Observatory reported that seismic activity in the area was continuing.
Background: Dabbahu, also known as Boina or Moina, is a Holocene volcanic massif forming an axial range of the Afar depression SSW of the Alayta massif. Pantelleritic obsidian flows, lava domes, and pumice cones form the summit and upper flanks of the volcano, which rises above the Teru Plain and was built over a base of basaltic-to-trachytic lava flows of a shield volcano. Late-stage basaltic fissure eruptions occurred at the NW base of the volcano. Abundant fumaroles are located along the crest of the volcano and extend NE towards Alayta.
Explosions and pyroclastic ejections continued at Dukono during 10-16 October. Ash columns rose 100-950 m above the summit (or 1,200-7,000 ft a.s.l.) and mainly drifted SE. Seismicity was dominated by explosion earthquakes. Dukono remained at Alert Level 2.
This year's second eruption of Piton de la Fournaise volcano was ufficially declared to have ended today, after tremor had ceased abruptly yesterday at 13:10h local time on the 18th of Oct. 2005 while visual observations had yesterday not been possible due to bad weather.
Marco Fulle sends this report based on observations made by a VolcanoDiscovery group, who climbed Stromboli on 11 Oct. 2005: Stromboli's activity was significant, with 8 active vents in three clusters (corresponding to the former W, Central and E craters): during 1 hour, they observed 2 faint eruptions from the W vent nr. 1, which is hidden from Pizzo, while stong glow was visible from the second vent in the W crater. During the same time, 5 eruptions occurred from the westermost vent in the central vent complex (the former Central crater), emitting few bombs but lots of gas during its eruptions, and seven (!) eruptions ejecting lava to up to 250 m height were observed from the second central vent, which is now found at the top of a tall cone. The eastern vent complex conprises 4 active vents: Blue flames were visible from E vent nr.1, while two simulataneous eruptions occurred from a second and third vent in the E crater, ejecting lava to up to 150 m. One of these vents is glowing visibly, the other one is hidden from Pizzo. A 4th vent, at the far E end of the E crater, is also hidden from Pizzo and was showing continuous spattering.
The tours this year on Santorini are now over, too, with lots of fun and great company as well. Thanks to all participants! Before we send out our formal newsletter, when the programs for 2006 are completed, a quick notice to announce that Tom will offer a new, 12-days tour / expedition to the Rift Valley including Lengai volcano in Feb. and summer 2006, Costa Rica in late March and (probably) July 2006. As well, Tobias (who is right now touring in the Saronic Gulf) awaits with a new, exciting program on Milos, a wonderful, volcanic island in Greece! Other new or recently developped programs include Nisyros (Greece) and the Eifel region in Germany (details will come soon). Greetings from Athens! Tom
The eruption at Piton de la Fournaise continues at stable low levels. According to the volcano observatory on the island, the new cone is slowly growing, showing moderate degassing, slightly increased today, weak spattering, and emitting lava flows that are still visible. By now, the new flows have covered 30-50% of the crater floor of Dolomieu crater.Tremor is low.
According to the Associated Press, Tanaga volcano in the Aleutian Islands is waking up. The Alaska Volcano Observatory observed this month tiny earthquakes appear under the volcano for the first time since a network of seismometers had been installed at the volcano two years ago.Tanaga last erupted in 1914.
The new cone that has formed in the SE area of Dolomieu crater (Photo published on Réunion's leading newspaper "Le Journal de l'île de la Réunion" - www.clicanoo.com)
The main vent of the new eruption remains active with moderate lava fountains and strombolian activity, emitting a few small lava flows inside Dolomieu crater. Since today, access to the Enclos has been reopened to the public on a temptative basis (on condition that visitors "behave"), but access is limited to the time between 6am and 5:30pm. More details (in French) on the following article. [read all]
The eruption at Piton de la Fournaise and volcanic tremor levels have stabilized and continue at low levels. Activity continues inside Domolieu crater, where a small cone of about 10 m height has been formed at the pricipal vent. Lava fountains and strombolian activity atteign heights of about 30 m occur and several active lava flows depart from the vent, sometimes as overflows from its crater that shows frequent inside collapses.
The weak intensity of tremor is probably due to the relatively ease with which magma rises from a shallow magma chamber to the surface. In fact, the area of the eruption has already been heavily fractured before: it appears that the magma is using approximately the same paths as during the Nov. 2002 eruption that occurred at the same site, as well as the subsequent eruptions in June, July and August 2003.
Authorities are discussing the possibilities to open access - free or organized - to the eruption site to the public.
The new fissure eruption of Piton de la Fournaise (photo Serge Gélabert, website of Réunion's leading newspaper "Le Journal de l'île de la Réunion" - www.clicanoo.com).
After a break of 4 months, Piton de la Fournaise volcano started its second eruption this year on October 4th at 14:26, after four months of almost continuous inflation and increased seismicity. A fissure opened inside Dolomieu crater at the same site as the December 2002 pit crater and the Mai-June 2003 eruption, producing lava fountains and lava flows.
One week after the start of the eruption of Erta Ale, some details emerge as news reports come in: the crater of the large shield volcano has rapidly filled with fresh lava and possibly overflowed, destroying farmland and killing much livestock. strong strombolian or hawaiian activity is producing thick clouds of ash that shower over the volcano's surroundings.
A group of scientists assessed the visible changes at Erta Ale on 26 September after activity began around 24 September. In comparison to observations made in November 2004, they found that the southern main crater/pit had widened significantly, with portions of the previous crater walls having collapsed into the lava lake. A new cone-shaped construct had grown within the southern main crater where there had been a platform. A lava lake occupied the entire width of the inner crater/pit. In the northern crater/pit, there was a solidified lava bulge and abundant "smoking" along the crater walls. No incandescent lava was visible in the pit. Based on descriptions by local residents of seeing "red and glowing light shooting and rising into the air above the volcano," the scientists believe that a Strombolian eruption probably occurred, emitting a significant volume of fresh magma within, and possibly out of, the pit.
No fatalities have been reported, but the Ethiopian government evacuated about 50,000 nomads in the surroundings of the volcano. A committee has been set up at to study the magnitude of the damage.
AP press photo showing the Santa Ana volcano in eruption on 1 Oct. 2005.
Santa Ana volcano, also known under its original name Llamatepecin, in El Salvador had a large explosive (Sub-Plinian) eruption on Saturday, October 1st, sending a column of ash about 16 km (ca. 50,000 feet) into the air. On 2 Oct., the volcano had quieted down, but the highest alert level is being maintained, because further explosive events cannot be excluded to occur in the near future.
The volcano had been showing increased seismicity since late August, and temperatures in its crater lake had been increasing. In mid-September, alert level had been rised to level 2 and evacuation preparation had begun.
During 22-27 September, several small explosions occurred at Colima. The largest explosion took place on 27 September at 0507 and produced a plume to a height of ~3.8 km above the volcano (or 25,100 ft a.s.l.). The plume drifted WSW, depositing small amounts of ash in the cities of Colima, Villa de Álvarez, and Comala more than 30 km from the volcano. Due to the threat of lahars forming on the volcano's flanks, Universidad de Colima advised avoiding the ravines of La Lumbre, San Antonio, Monte Grande (in Colima state), and La Arena (in Jalisco state).
Erta Ale volcano in northern Afar, Ethiopia, well-known for its long-lived active lava lake that had occupied its crater up until 2004, erupted yesterday according to unconfirmed reports from local authorities. The eruption followed a series of earthquakes of up to 5.5. magnitude Richter scale that occurred in the area the day before.
Shiveluch volcano started a new eruption on Thursday-Friday night. An ash plume has reached 7.5 km above sea level, and a lava flow is descending 15 km from the summit.
Colima continues to be at moderately high levels of activity. A strong explosion occurred yesterday on Sept. 16, at 10:46 am local time, producing an ash plume about 5 km high (3 miles). The eruption was accompanied by loud detonations that could be heard in villages up to 15 km away from the volcano. Ash-fall occurred in villages and towns to the northeast of Colima.
A relatively stronger, but still small explosive eruption occurred at Fuego on 17 July during 1715-1945 local time, producing an ash plume that rose 3.5-4 km above the volcano's crater (or 23,800-25,500 ft a.s.l.). The eruption was accompanied by small pyroclastic flows that traveled SW down Santa Teresa and Taniluyá ravines.
- I am finally back in Europe, Doni and me wish to thank you all a lot for the great company, and the good tour we've had together. I will gradually post more photos of the tour on this website as well as on www.decadevolcano.net. Greetings from Athens,-
During 1-5 September, volcanic activity at Tungurahua remained at low levels with small emissions of steam, gas, and variable ash content. On 1 September, ash fell in the Puela sector, ~ 8 km SW of the summit.
Background: 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 been restricted to the summit crater. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano.
Growth of the new lava dome inside the crater of Mount St. Helens continued during 31 August to 6 September, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. On 6 September, dry conditions and rockfalls from the lava dome generated occasional ash plumes that rose above the volcano and rapidly dissipated. St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange.
Growth of Shiveluch's lava dome continued during 26 August to 2 September, and viscous lava continued to flow at the lava dome. Several ash plumes reached ~5.5 km (18,050 ft) a.s.l. Shiveluch remained at Concern Color Code Orange.
During 1-6 September, seismicity and gas emissions were above normal levels at Santa Ana as they had been since 27 July. Tremor continued to be recorded, and on 2 August a cluster of at least eight small earthquakes occurred. The earthquakes were not felt by local residents. During the report period, gas plumes rose to ~500 m above the volcano (or 9,400 ft a.s.l.) and the sulfur- dioxide flux was over 1,000 metric tons per day. Satellite imagery from 5 September showed a thermal anomaly at the volcano. Santa Ana remained at Alert Level Yellow Phase 1.
Background: Santa Ana, El Salvador's highest volcano, is a massive stratovolcano immediately W of Coatepeque caldera. The San Marcelino cinder cone on the SE flank produced a lava flow in 1722 that traveled 11 km to the E.
Based on information from JMA, the Tokyo VAAC reported that an eruption occurred at Sakura-jima on 2 September at 0927. The resultant ash plume reached a height of ~2.1 km (7,000) ft a.s.l. and drifted NW.
Background: 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. The largest historical eruption took place during 1471-76.
During 22-28 August, there was a decrease in activity at Reventador in comparison to the previous week. Seismicity and gas emissions decreased at the volcano, and no surficial changes were observed. On 1 September a pilot reported an ash cloud to the Washington VAAC, but no ash was visible on satellite imagery.
During 1-5 September, lava from Kilauea entered the sea at the East Lae`apuki area, and surface lava flows were visible on the Pulama Pali fault scarp. On 27 August, part of a lava bench (land built out from the sea cliff) collapsed.
Background: 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. This long-term ongoing eruption from Pu`u `O`o-Kupaianaha has produced lava flows that have traveled 11-12 km from the vents to the sea, paving about 104 km2 of land on the S flank of Kilauea and building more than 200 hectares of new land.
A plume from Dukono was observed on satellite imagery on 2 September at a height of ~3 km a.s.l. extending NW.
Background: Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred since 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya.
During 31 August to 6 September, several small explosions occurred at Colima. On 31 August during 1245-1330, a seismic signal associated with a lahar was recorded at the Monte Grande station.
Background: 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.
Frequent historical eruptions date back to the 16th century.
On 1 September, a plume from Barren Island was visible on satellite imagery at a height of ~3 km a.s.l. extending ~90 km NE of the summit. The current eruption of Barren Island began on 28 May.
Background: Barren Island, a possession of India in the Andaman Sea about 135 km NE of Port Blair in the Andaman Islands, is the only historically active volcano along the N-S-trending volcanic arc extending between Sumatra and Burma (Myanmar). The 354-m-high island is the emergent summit of a volcano that rises from a depth of about 2,250 m. Lava flows fill much of the caldera floor and have reached the sea along the western coast during eruptions in the 19th century and more recently in 1991 and 1995.
During 1-3 September, eruptive activity continued at Anatahan with ash plumes rising to a maximum height of ~3 km a.s.l.
Background: The elongate, 9-km-long island of Anatahan in the central Mariana Islands consists of large stratovolcano with a 2.3 x 5 km, E-W-trending compound summit caldera. The larger western caldera is 2.3 x 3 km wide, and its western rim forms the island's 790-m high point. The first historical eruption of Anatahan did occur May 2003, when a large explosive eruption took place forming a new crater inside the eastern caldera.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands and the US Geological Survey Hawaiian Volcano Observatory http://volcanoes.usgs.gov/updates.html
