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Posts Tagged ‘Koryaksky’

VolcanoWatch Weekly [9 September 2009]

Posted by feww on September 11, 2009

VOW: Toba the Sleeping Colossus

Toba
Lake Toba, Sumatra, Indonesia – Landsat photo – Source: NASA

Lake Toba is a supervolcano, 100 kilometres long and 30 kilometres wide, and 505 metres (1,666 ft) at its deepest point. Located in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about 900 metres (2,953 ft), the lake stretches from 2.88°N 98.52°E  to 2.35°N 99.1°E.  It is the largest volcanic lake in the world. It’s also the site of a supervolcanic eruption that occurred about 74,000 years ago, a massive climate-changing event. The eruption is believed to have had a VEI intensity of 8. This eruption, believed to have been the largest anywhere on Earth in the last 25 million years, may have had catastrophic consequences globally; some anthropologists and archeologists believe that it killed most humans then alive, creating a population bottleneck in Central Eastern Africa and India that affected the genetic inheritance of all humans today. (Source: Wikipedia).

Toba Large
Lake Toba Topography.
Source: Andaman Org.

Toba catastrophe theory

The Toba catastrophe theory holds that 70,000 to 75,000 years ago, a supervolcanic event at Lake Toba, on Sumatra, plunged the Earth into a mini-ice-age lasting several thousand years, reducing the world’s human population to 10,000 or even a mere 1,000 breeding pairs, creating a bottleneck in human evolution. The theory was proposed in 1998 by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign.

The Toba eruption (the Toba event) occurred at what is now Lake Toba about 67,500 to 75,500 years ago. It had an estimated Volcanic Explosivity Index of 8 (described as “mega-colossal”), making it possibly the largest explosive volcanic eruption within the last twenty-five million years. It had a volume 300 cubic km greater than the Island Park Caldera supereruption (2500 cubic km) of 2.1 million years BP.

The total amount of erupted material was estimated at about 2,800 km³ — about 2,000 km³ of ignimbrite that flowed over the ground, and some 800 km³ that fell as ash, with the wind blowing most of it to the west. The pyroclastic flows of the eruption destroyed an area of 20,000 square kilometers, with ash deposits as thick as 600 metres near the main vent [ cf, 1980 eruption of Mount St. Helens ejected about 1.2 km³;  of material, whilst the largest volcanic eruption in historic times, at Mount Tambora in 1815, emitted the equivalent of 100 km3 of dense rock.] The eruption was also about three times the size of the latest Yellowstone eruption of Lava Creek 630,000 years ago. (Source: Wikipedia).

volcanic features of toba
The eruption of 73,000 years ago left the Sibandung caldera.  Lake Toba is surrounded by two small, active volcanos as well as several updomed areas and hot springs. These features indicate that there is activity below the surface today and that pressure is rising. Samosir island, too, is evidence for upthrust from below. From the record it seems that Toba produces major eruptions every 300-400,000 years. Source: Andaman Org.

Volcanic features in and around Lake Toba:

Grey area: Present-day topographic depression
green area: Updomed areas

Area # 1.  Sibandung caldera: made 73,000 years ago by the Toba YTT event (Young Toba Ash)
Area # 2. Haranggaol caldera: made 500,000 years ago by the Toba MTT event (Middle Toba Ash)
Area # 3.  Sibandung caldera: made 800,000 years ago by the Toba OTT event (Old Toba Ash)

The MTT and OTT events were not as large as the YTT event of 73,000 years ago
but were still major eruptions of at least VEI 7.

V1 Tandukbenua (Sipisopiso) – young dacit-andesite volcano
V2 Pusubukit volcano – young dacit-andesite volcano
D1 Pardepur dacite domes
D2 Tuk-tuk rhyolite dome
HS Hot springs
Source: Andaman Org.

Recent Activity

Large earthquakes have occurred in the vicinity of the volcano more recently, notably in 1987.  Other earthquakes have occurred in the area in 1892, 1916, and 1920-1922.

Lake Toba lies near the Great Sumatran fault which runs along the centre of Sumatra called the Sumatra Fracture Zone. The volcanoes of Sumatra and Java are part of the Sunda Arc, a result of the northeasterly movement of the Indo-Australian Plate which is sliding under the eastward-moving Eurasian Plate. The subduction zone in this area is very active: the seabed near the west coast of Sumatra has had several major earthquakes since 1995, including the 9.3 2004 Indian Ocean Earthquake [followed by the deadly tsunami] and the 8.7 2005 Sumatra earthquake, the epicenters of which were around 300 km from Toba Lake. (Source: Wikipedia).

SI /USGS Weekly Volcanic Activity Report
(26 August-1 September 2009)

New activity/unrest:

Notes [Source: GVP]

RVO reported that during 28 August-3 September white and gray ash plumes from Rabaul caldera’s Tavurvur cone rose 1.5 km above the crater and produced ashfall in Rabaul town (3-5 km NW) and surrounding areas.

The Washington VAAC reported that on 6 September an explosion from San Cristóbal produced an ash plume that rose to an altitude no higher than 8.5 km (28,000 ft) a.s.l. The plume drifted 75 km W.

Ongoing Activity:

Related Links:

FEWW Links:

FEWW Volcanic Activity Forecast

Posted in Sumbawa Island, Supervolcanoes, toba, Toba catastrophe theory, toba lake, toba volcano, Volcanic Activity Report, VolcanoWatch, VolcanoWatch Weekly | Tagged: , , , , , , , , , , | Comments Off

VolcanoWatch Weekly [27 August 2009]

Posted by feww on August 28, 2009

Volcanic Activity Report: 19 August – 25 August 2009

VOW: Koryaksky

koryaksky_amo_2009239
Koryaksky Volcano on Russia’s Kamchatka Peninsula released a plume on August 27, 2009, caught by MODIS on NASA’s Aqua satellite. The volcano has released intermittent ash and/or steam plumes late August.

This true-color image shows a pale plume, which consists primarily of water vapor, blowing away from the summit east-northeast, toward the Bering Sea.

Vostok Media reported simultaneous activity at six Kamchatka volcanoes, describing  the first concurrent unrest in 60 years as rare. NASA image courtesy MODIS Rapid Response Team, Goddard Space Flight Center. Caption by Michon Scott. [Edited by FEWW.]

New activity/unrest:

Source: Global Volcanism Program (GVP) – SI/USGS Weekly Volcanic Activity Report

KORYAKSKY Eastern Kamchatka 53.320°N, 158.688°E; summit elev. 3,456 m

KVERT reported that during 14-21 August seismic activity from Koryaksky was slightly above background levels. During 13-16 August, gas-and-steam plumes rose to altitudes of 3.5-5 km (11,500-16,400 ft) a.s.l. Based on visual observations during 16-20 August, gas-and-steam plumes containing ash rose to altitudes of 3.5-4.2 km (11,500-13,800 ft) a.s.l. and drifted in multiple directions. Ash plumes were also seen in satellite imagery, drifting 215 km E and W. On 23 August, a probable ash plume detected in satellite imagery drifted 50 km ESE. During 24-25 August, seismicity increased; more than 100 earthquakes were recorded. The Level of Concern Color Code remained at Orange.

Geologic Summary. The large symmetrical Koryaksky stratovolcano is the most prominent landmark of the NW-trending Avachinskaya volcano group, which towers above Kamchatka’s largest city, Petropavlovsk. Erosion has produced a ribbed surface on the eastern flanks of the 3456-m-high volcano; the youngest lava flows are found on the upper western flank and below SE-flank cinder cones. No strong explosive eruptions have been documented during the Holocene. Extensive Holocenefissure vents about 3900-3500 years ago reached Avacha Bay. Only a few moderate explosive eruptions have occurred during historical lava fields on the western flank were primarily fed by summit vents; those on the SW flank originated from flank vents. Lahars associated with a period of lava effusion from south- and SW-flank time. Koryaksky’s first historical eruption, in 1895, also produced a lava flow. (Source: GVP).

Notes:

Based on information from the Tegucigalpa MWO, the Washington VAAC reported that ash was detected within 15 km of Fuego on 19 August. According to INSIVUMEH, rumbling sounds were accompanied by incandescent tephra ejected 75 m high on 21 August. (Source: GVP).

Ongoing Activity:

Related Links:

FEWW Links:

Volcanic Activity Report, Volcano Hazard, VolcanoWatch, volcanism, volcanoes. Tagged: , , , , , , , .

Posted in Volcanic Activity Report, volcanism, Volcano Hazard, volcanoes, VolcanoWatch | Tagged: , , , , , | 1 Comment »

VolcanoWatch Weekly [20 August 2009]

Posted by feww on August 22, 2009

Volcanic Activity Report: 12 August-18 August 2009

VoW: Talang

Talang
The Indonesian volcano Talang on the island of Sumatra had been dormant for centuries when, in April 2005, it suddenly rumbled to life. A plume of smoke rose 1000 meters high and nearby villages were covered in ash. Fearing a major eruption, local authorities began evacuating 40,000 people. Caption: James A. Phillips, NASA.

And just to confuse the readers a little, the following caption is by volcano.oregonstate.edu

Talang is a stratovolcano with 8 confirmed eruptions between 1833 and 1968. The volcano may have had a phreatic eruption in 1986 but the activity has not been confirmed. Most of the eruptions are moderate in size (VEI=2) and explosive. Eruptions in 1833, 1843, 1845, and 1876 were from flank vents. An eruption in 1967 and two different eruptions in 1968 were from radial fissures. The distance from the city of Padang to Talang is about 35 km. Image courtesy of the Landsat Pathfinder Project.

TALANG
Country: Indonesia
Region: Sumatra
Last Known Eruption: 2007
Summit Elevation: 2,597 m (8,520 feet)
Latitude: 0.978°S  (0°58’42″S)
Longitude:  100.679°E (100°40’46″E)
Source: GVP


Talang, which forms a twin volcano with the extinct Pasar Arbaa volcano, lies ESE of the major city of Padang and rises NW of Dibawah Lake. Talang has two crater lakes on its flanks; the largest of these is 1 x 2 km wide Danau Talang. Most historical eruptions have not occurred from the summit of the volcano, which lacks a crater. Historical eruptions from Gunung Talang volcano have mostly involved small-to-moderate explosive activity first documented in the 19th century that originated from a series of small craters in a valley on the upper NE flank. Photo by Ruska Hadian, 1986 (Volcanological Survey of Indonesia). Caption: GVP.

Authorities raise Mt. Talang alert level to highest

The vulcanology and disaster mitigation office in West Sumatra has raised the alert status for Mt. Talang to the highest level following a 6.9-magnitude earthquake and a series of aftershocks that struck the province.

Vulcanologist Dalipa Marjusi said Tuesday the tremors had sparked a volcanic earthquake and temblors, although eruption of the volcano remained undetected.

“Since Sunday’s earthquake we have recorded 1,600 volcanic quakes and 700 tectonic quakes, but only 23 of them were felt,” Dalipa said.

Fog has blanketed the summit of the 2,597-meter volcano for the last two days, making it difficult to see ash or lava that might be erupting from its crater.

The volcano last spewed hot ash last April.

A seven-strong team from the directorate general of vulcanology and disaster mitigation have arrived in Padang from Bandung to monitor the volcano’s activities.
Source: http://www.thejakartapost.com/news/2009/08/18/authorities-raise-mt-talang-alert-level-highest.html


Talang is the 6th listed volcano from top left.

New activity/unrest:

Source: Global Volcanism Program (GVP) – SI/USGS Weekly Volcanic Activity Report

Notes:

IG reported that on 4 August seismicity from Reventador increased and periods of tremor frequently saturated the seismic stations. On 6 August, incandescent blocks were ejected from the crater. Thermal images revealed a linear area of higher temperatures, confirming the presence of a new lava flow on the S flank.

Based on analyses of satellite imagery, the Washington VAAC reported that on 14 August a 2-hour-long thermal anomaly detected over Pagan was followed by a small emission. The emission, hotter than its surroundings, drifted NW and quickly dissipated. [Source: GVP]

Ongoing Activity:

Related Links:

FEWW Links:

Posted in Volcanic Activity Report, volcanism, Volcano Hazard, volcanoes, VolcanoWatch | Tagged: , , , , , , , | Leave a Comment »

Weekly Volcano Watch: 19 March 2009

Posted by feww on March 19, 2009

Volcanic Activity Report: 11 March – 17 March 2009

Source: SI / USGS Weekly Volcanic Activity Report

New activity/unrest:

VoW: Hunga Tonga-Hunga Ha’apai, Tonga

Tonga Islands 20.57°S, 175.38°W; summit elev. 149 m – submarine volcano

An underwater volcanic eruption near the twin islands of Hunga Tonga and Hunga Ha’apai spewed a large column of  off-white smoke into the air. The plume rose to altitudes of about 8 km [possibly as high as 15km.]

tonga-ap
Hunga Ha’apai eruption [March 17-18, 2009] Aerial photo by Trevor Gregory/AP. Source. Image may be subject to copyright.

Observers flying near the area of Hunga Tonga-Hunga Ha’apai (about 62 km NNW of Nuku’alofa, the capital of Tonga) on 16 or 17 March reported seeing an eruption. Photos showed an eruption plume with a wide base that rose from the sea surface and mixed with meteorological clouds. Based on information from the Tonga airport and analysis of satellite imagery, the Wellington VAAC reported that on 18 March, a plume rose to altitudes of 4.6-7.6 km (15,000-25,000 ft) a.s.l. and drifted NE.

Geologic Summary. The small islands of Hunga Tonga and Hunga Ha’apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of a the rim of a largely submarine caldera lying east and south of the islands. Hunga Tonga and Hunga Ha’apai reach an elevation of only 149 m and 128 m above sea level, respectively, and display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera. A rocky shoal 3.2 km SE of Hunga Ha’apai and 3 km south of Hunga Tonga marks the most prominent historically active vent. Several submarine eruptions have occurred at Hunga Tonga-Hunga Ha’apai since the first historical eruption in 1912. GVP reported.


The small islands of Hunga Tonga and Hunga Ha’apai cap a large seamount located about 30 km SSE of Falcon Island. The two linear andesitic islands are about 2 km long and represent the western and northern remnants of a the rim of a largely submarine caldera lying east and south of the islands. Hunga Tonga and Hunga Ha’apai reach an elevation of only 149 m and 128 m above sea level, respectively, and display inward-facing sea cliffs with lava and tephra layers dipping gently away from the submarine caldera. A rocky shoal 3.2 km SE of Hunga Ha’apai and 3 km south of Hunga Tonga marks the most prominent historically active vent. Submarine eruptions were reported here in 1912 and 1937 and from a fissure 1 km SSE of Hunga Ha’apai in 1988. Aerial photo by Tonga Ministry of Lands, Survey, and Natural Resources, 1991 (published in Taylor and Ewart, 1997). Caption: GVP.


Hunga Tonga-Hunga Ha’apai volcano from space. Image captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite  on March 18, 2008. “In this image, the area around the eruption appears bright blue-green, likely resulting from sediment suspended in the water. The brilliant white patch at the center of the sediment-rich area may result from vapor released by the volcano. Northwest of the eruption site, a serpentine pumice raft floats on the water. The highly porous nature of pumice enables this volcanic rock to form floating rafts. (A larger pumice raft resulted from a similar eruption in the Tonga Islands in August 2006.).” Earth Observatory said.


A March 18 photo of Hunga Tonga-Hunga Ha’apai eruption as seen from the Nuku’alofa waterfront. Photo: AP/Matangi Tonga Online. Source. Image may be subject to copyright.

volcanoes-of-tonga
USGS Map of Major Volcanoes of Tonga with the approximate location of
Hunga Tonga-Hunga Ha’apai volcano marked.


Photo dated
Wednesday, March 18, 2009. Source: Xinhua/AFP. Image may be subject to copyright.

Video: Underwater volcano erupts off Tonga

Hunga Tonga-Hunga Ha’apai volcano

Flights were disrupted and airlines alerted after the undersea Hunga Tonga-Hunga Ha’apai volcano erupted.  Air New Zealand flights were forced to divert to  avoid  smoke, which reportedly rose to a height of about 15 km, various media reported.

The volcano located about 12km off the southwest coast off the main island of Tongatapu  is thought to have erupted on Monday. Hunga Tonga-Hunga Ha’apai is one of about 40 submarine volcanoes in the area.

It’s thought that the eruption does not pose an immediate threat to the residents because trade winds are blowing the smokes and  gases away from the island.

“It’s a very significant eruption, on quite a large scale.” Said Tonga’s Geological Service Chief, Keleti Mafi.

Rumble III

On March 13, the underwater volcano Rumble III,  located about 300km northeast of Bay of Plenty, New Zealand, was discovered to have undergone a “startling change” losing about 100m of its summit, with the 800m-wide crater completely missing, apparently in a catastrophic explosion.

Metis Shoal

On February 3, FEWW forecast that Metis Shoal, a submarine volcano located midway between the islands of Kao and Late (about 50 km NNE of Kao), was about to erupt, or was currently undergoing a period of unrest.

FEWW moderators believe that both  Metis Shoal, if indeed it has erupted / is erupting, and Hunga Tonga-Hunga Ha’apai volcanoes may have been triggered simultaneously.

FEWW List of Forgotten Volcanoes

Ongoing Volcanic Activity:

Elevated Volcanic Activity and Information Releases

Wednesday, Mar 18, 2009 at 17:47:50 PDT.

The following U.S. volcanoes are known to be above normal background (elevated unrest or eruptions) or have shown activity that warranted an Information Release (for example, an earthquake swarm).

Times are local to the volcano and in 24-hr format.
Volcano Alert Levels & Aviation Color Codes defined at http://volcanoes.usgs.gov/activity/alertsystem.

Volcano Hazards Program Webcams page links to webcams at 19 of the 169 active volcanoes in the U-S.

Related Links:

Posted in Chaiten, Galeras, Metis Shoal, Redoubt, Rumble III | Tagged: , , , , | 2 Comments »

 
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