General Volcanic Activity Thread!

[john pike]

The Volcanological and Seismological Observatory of Costa Rica (OVSICORI) recorded two phreatic eruptions at the Poas Volcano yesterday morning. The first eruption occurred at 9:55 a.m. and reached a height of between 2 to 3 meters. The second eruption occurred at 11:16 a.m., reaching an estimated height of 10 to 15 meters. The Director of OVSICORI, Victor Gonzalez, said the eruptions were not unusual for Poas, though did say that the low level of the volcano’s lagoon, despite significant rainfall, was striking. The National Emergency Commission (CNE) maintains a green alert in Turrialba, Poas and Rincon de la Vieja due to phreatic eruptions and seismic activity in recent months.

 

http://hisz.rsoe.hu/alertmap/site/?pageid=event_desc&edis_id=VE-20130821-40627-CRI

[john pike]

Possible glacier flood from Hofsjökull volcano

Posted on August 21, 2013 by Jón Frímann

 

It has been reported today that possible glacier flood has taken place in Hofsjökull volcano. Reports did come to Icelandic Meteorological Office that a glacier river named Jökulsá Vestri in Skagarfirði (Wikipedia). It is not known what is causing this change in the glacier river, it might be anything from a mud slide to change in the glacier itself. Amount of water in the glacier river has not changed according to IMO monitoring of the river.

Smell of sulfur has been reported with this change in the glacier river. That means the water has been in contact with hydrothermal areas that are under Hofsjökull glacier (volcano). No earthquake activity or change of any type has taken place following this change in Jökulsá Vestri in Skagarfirði.

If anything more happens. I am going to update this blog post or post an new one if I need to.

Icelandic News on this event

Jökulsá Vestari óvenjuleg á litin (Rúv.is)

Brennisteinslykt við Goðdali (mbl.is)

 

http://www.jonfr.com/volcano/

 

[john pike]

Kizimen volcano (Kamchatka) activity update: growing lava dome and incandescent rock avalanches

http://www.volcanodiscovery.com/kizimen/news/36512/Kizimen-volcano-Kamchatka-activity-update-growing-lava-dome-and-incandescent-rock-avalanches.html

See link above it also has 2 time lapse videos

[john pike]

Karymsky (Kamchatka): Activity has remained elevated. A series of ash emissions caused by moderately strong vulcanian-type explosions occurred over the past days. This morning, an ash plume rose to 8,000 ft (2.4 km) altitude and drifted east.

Shiveluch (Kamchatka): The volcano continues to extrude a new lobe of viscous lava (visible as the dark patch in the webcam image) at the lava dome, as well as produce occasional (usually small) ash explosions.

Poas (Costa Rica): A series of small phreatic eruptions occurred on 20 August at the crater lake. The first occurred at 09:55 (local time), ejecting mud and water to 2-3 m height, and a second one, more powerful, at 11:16 reached heights of 10-20 m.

 

http://www.volcanodiscovery.com/volcanoes/today.html

[john pike]

JAKARTA, Indonesia—Indonesian authorities have been warning local villagers in East Nusa Tenggara Province about increasing volcanic activities in the area in recent days.

Agence France-Presse/Getty Images Mount Rokatenda volcano, shown here on Aug. 12, killed six people on Palue island two days earlier. Authorities are now watching two other volcanoes, subsea Mount Hobalt and and Mount Ili Werung, in the same eastern province.

“The people around the areas should continue to practice caution†despite there not having been fresh volcanic activity  on Wednesday,  said Sutopo Purwo Nugroho, the spokesman of the National Disaster Mitigation Agency.

The agency reported on Tuesday two volcanoes in the East Nusa Tenggara Province have shown “increasing activities.†The volcanoes are subsea Mount Hobalt and and Mount Ili Werung.

It noted Mount Hobalt erupted Tuesday morning, spewing cloud as high as 6,560 feet above the sea level for around two minutes.

“Visually, the water near the volcano turned yellow and bubbly,†the agency said.

Meanwhile,  Mount Ili Werung, located on the southern part of Lembata Island, started rumbling just before dusk Tuesday for about an hour and a half.

But the agency said, at least so far, it isn’t necessary for the villagers to evacuate their villages.

Six people were killed in the small Palue Island in the province when Mount Rokatenda erupted on Aug. 10, spewing hot ash and smoke up to 6,560 feet into the air. Nearly 3,000 people were evacuated from the area in the island since it first rumbled in October 2012.

East Nusa Tenggara is about  1,297 miles east of Indonesia’s capital city of Jakarta.  Just west to the province is West Nusa Tenggara Province, famous for the Mount Tambora, whose eruption in April 1815 is cited as the largest volcanic eruption in the world in recorded history.  The precise death toll from the eruption remains unclear, but it is believed to be at least 71,000. The eruption caused a “volcanic winter,†a reduction in temperature cause by volcanic ash and droplets of sulfuric acid. It made 1816 known as the year without summer due to the effects of the weather in North America and Europe.

 

http://blogs.wsj.com/searealtime/2013/08/22/indonesia-warns-of-rising-volcanic-activity-in-east-province/

Edited August 22, 2013 by john pike

[john pike]

MODIS hot spot data (past 7 days) for Sakurajima

volcano (ModVolc, Univ. Hawaii)

Yesterday's eruption of Santiaguito (webcam image: INSIVUMEH, annotated by Blog Culture Volcan)

 

 

Sakurajima (Kyushu, Japan): On 21 August, the volcano had at least 8 (!) vulcanian-type explosions with ash plumes rising up to 15,000 ft (4,5 km) altitude that often drifted over the bay and Kagoshima city, causing ash fall there. Some of the explosions can be seen on the following time-lapse video. The volcano has been in an elevated state of activity during the past weeks. A significant hot spot is visible on MODIS data, suggesting that magma levels are high in the crater and the presence of significant amounts of still hot fresh deposits on the flanks.

 

 

Santa María / Santiaguito (Guatemala): A major eruption occurred yesterday evening. Starting at 17:45 (local time), the top part of the Caliente lava dome collapsed and produced a series of relatively large pyroclastic flows and explosions. Ash plumes rose more than 2 km to elevations of 4 km altitude.
The cause of the eruption was likely the accumulation of pressurized magma and gas under the dome composed of viscous (solid) lava.
... [show less]
The pyroclastic flows affected mainly the south, southeast and NNE sides. Bombs from explosive activity were ejected to distances of 500 m.

 

http://www.volcanodiscovery.com/volcanoes/today.html

 

 

 

Volcano Eruption in Guatemala on Friday, 23 August, 2013 at 12:07 (12:07 PM) UTC.

 

A major eruption occurred yesterday evening. Starting at 17:45 (local time), the top part of the Caliente lava dome collapsed and produced a series of relatively large pyroclastic flows and explosions. Ash plumes rose more than 2 km to elevations of 4 km altitude. The cause of the eruption was likely the accumulation of pressurized magma and gas under the dome composed of viscous (solid) lava. The pyroclastic flows affected mainly the south, southeast and NNE sides. Bombs from explosive activity were ejected to distances of 500 m.

 

http://hisz.rsoe.hu/alertmap/site/?pageid=event_desc&edis_id=VE-20130823-40649-GTM

 

Edited August 23, 2013 by john pike

[john pike]

[john pike]

Rome (Italy): new fumarole near Fiumicino airport

Monday Aug 26, 2013 15:10 PM | BY: T

What appears to be a new fumarole appeared near Rome's International Fiumicino airport Saturday morning. A vent producing small geyser-like fountains of steam, water and mud suddenly opened in the ground near a road crossing near Fiumicino.

Geologists are currently examining the phenomenon. It is still a bit unclear whether it is not a man-made accident caused by a broken pipe or similar (which might well be the case). As La Repubblica statess, first inspections however indicate that ii is in fact a new natural vent. Obviously, there are also already some speculations whether it could be related to volcanic activity.

The nearest possibly still active volcanic system in the area is the Monti Albani, an old but possibly not yet extinct volcanic complex located 20 km SE of the capital. Its last known activity there took place about 20,000 years ago.

New volcanic activity in the suburban area of Rome itself is certainly not a completely impossible, but quite unlikely scenario. More data will be needed to shed light on this.

http://www.volcanodiscovery.com/monte-albano/news/36609/Rome-Italy-new-fumarole-near-Fiumicino-airport.html

[john pike]

Eurasia's highest volcano, Klyuchevskoi, on the Kamchatka Peninsula in Russia's Far East, began erupting, Russia’s Skanex research and development center said in a statement on Tuesday. According to the statement, powerful explosions were registered in the upper part of the volcanic neck. The volcano spews ash some 200-300 meters (650-985 feet) high in the air, while gas and vapor emissions occur within an interval of three to five minutes. Apart from powerful mud flows that could form from ice thawing on the volcano's sides, the current eruption of Klyuchevskoi does not pose a threat to locals. Experts, however, say that the eruption could pose a threat to tourists visiting the volcano and local air traffic. Last time the volcano erupted was in 2010, but its most powerful eruption in the recent years was registered between January and May of 2005. Following that eruption, the volcano "sank" by 50 meters (about 165 feet), from 4,800 meters (about 16,000 feet) to the current 4,750 meters (15,845 feet).

[john pike]

Volcanic activity worldwide 28 Aug 2013: Pacaya, Kliuchevskoi, Tolbachik, Santa María / Santiaguito...

http://www.volcanodiscovery.com/volcano-activity/news/36672/Volcanic-activity-worldwide-28-Aug-2013-Pacaya-Kliuchevskoi-Tolbachik-Santa-Mara-Santiaguito.html

[cyclonic happiness]

Rome (Italy): new fumarole near Fiumicino airport

Monday Aug 26, 2013 15:10 PM | BY: T

What appears to be a new fumarole appeared near Rome's International Fiumicino airport Saturday morning. A vent producing small geyser-like fountains of steam, water and mud suddenly opened in the ground near a road crossing near Fiumicino.

Geologists are currently examining the phenomenon. It is still a bit unclear whether it is not a man-made accident caused by a broken pipe or similar (which might well be the case). As La Repubblica statess, first inspections however indicate that ii is in fact a new natural vent. Obviously, there are also already some speculations whether it could be related to volcanic activity.

The nearest possibly still active volcanic system in the area is the Monti Albani, an old but possibly not yet extinct volcanic complex located 20 km SE of the capital. Its last known activity there took place about 20,000 years ago.

New volcanic activity in the suburban area of Rome itself is certainly not a completely impossible, but quite unlikely scenario. More data will be needed to shed light on this.

http://www.volcanodiscovery.com/monte-albano/news/36609/Rome-Italy-new-fumarole-near-Fiumicino-airport.html

Found a video on it.

 

Looks very interesting but let's hope for Italy and Rome that the thing doesn't go all 'Paricutin' on us!!

 

 

[karyo]

Found a video on it.

 

Looks very interesting but let's hope for Italy and Rome that the thing doesn't go all 'Paricutin' on us!!

 

 

 

There's something surreal about it! Imagine waking up in the morning and finding this in your garden!

 

Karyo

[john pike]

Vulcanologists warn that the magma chamber beneath Japan's Sakurajima volcano is about 90per cent full which means a large lava eruption cannot be ruled out. It's been erupting constantly for nearly 60 years, spewing out smoke and ash and sending shivers through the more than half-a-million people who live nearby. Japan's Sakurajima volcano recently blasted 100-thousand tonnes of ash more than five-kilometres into the sky, reminding surrounding communities of its power and volatility.

http://hisz.rsoe.hu/alertmap/site/?pageid=event_update_read&edis_id=VE-20130818-40573-JPN&uid=14249

[john pike]

Volcanic activity worldwide 1 Sep 2013: Guntur

Sunday Sep 01, 2013 19:04 PM |

Guntur (West Java): The alert level was again raised to level 2 on a scale of 0-4 (Waspada, "watch") following an increase in seismic activity observed since 15 August.

An elevated number of volcano-tectonic earthquakes (related to rock-fracturing) and the appearance of tremor (indicating magma movements) suggest that new magma could be currently intruding into the volcanic system and lead to new activity which would threat numerous nearby villages and the town of Garut located only about 8 km away from the summit.

 

 

http://www.volcanodiscovery.com/volcano-activity/news/36748/Volcanic-activity-worldwide-1-Sep-2013-Guntur.html

 

 

Volcanoes Today, 1 Sep 2013: Momotombo

Sunday Sep 01, 2013 21:04 PM |

Seismic recording from Momotombo volcano (MOMN station, INETER)

 

http://www.volcanodiscovery.com/volcanoes/today.html

 

Momotombo (Nicaragua): The earthquake crisis has intensified today and developed into a swarm of shallow (around 5 km depth) earthquakes SE of the volcano. INETER reported already more than 30 quakes between magnitude 1-3 today.

There is no official statement available so far, although this might well be a precursor for a possible eruption in the near future

[john pike]

Found a video on it.

 

Looks very interesting but let's hope for Italy and Rome that the thing doesn't go all 'Paricutin' on us!!

 

 

 

hi cc

 

thanks for that

 

looks fairly ominous

 

have a look at this link

http://cnt.rm.ingv.it/earthquakes_map.html

 

clearly shows a high uptake of quakes at present

 

hard to call exactly whats going on there but keep watching to see if any larger quakes effect mid or southern italy

[john pike]

http://volcanoes.usgs.gov/volcanoes/long_valley/long_valley_monitoring_1.html

 

maybe worth a watch at present

 

long valley area in california

 

137 quakes in 6 days

 

http://hisz.rsoe.hu/alertmap/read/index.php?pageid=svolcano_index&svid=15

 

waiting to see whether these are volcanic or plate movement

 

update more when more info is available

[Coast]

 

Scientists reported increased activity at one of Alaska’s largest volcanoes on Friday, but geologist Chris Waythomas said it was unrelated to the earthquake that shook the Aleutian Islands that morning. Waythomas said the increased seismicity at the Veniaminof Volcano, on the Alaska Peninsula, started before the magnitude 7.0 earthquake struck, and the two are too far apart.

 

The Alaska Volcano Observatory reported increased activity, including lava fountaining and ash emissions up to 20,000 feet, from the volcano on Friday morning. Waythomas, a geologist with the U.S. Geological Survey at the observatory, said scientists have been monitoring increased activity at the site since early June. He said the volcano has had some significant past eruptions but nothing that scientists are seeing now suggests anything major is in the works this time. Rather, he suspects there will be a protracted period of the same kind of activity that scientists have been watching.

 

Veniaminof is about 480 miles southwest of Anchorage; Perryville is the nearest community to the volcano, about 20 miles away, and it received trace amounts of ash fall Friday, Waythomas said — like a dusting on the windshields of vehicles. Depending on how the wind blows, the Chignik area also could see some ash but amounts should be minimal, and there could be some impact on local air travel, he said. According to the observatory, the volcano, which has an ice-filled summit caldera, is one of the most active volcanic centers in the Aleutian Arc. It has erupted at least 13 times in the past 200 years, with what were characterized as minor ash-producing explosions in 2002, 2004, 2005, 2006 and 2008.

 

Waythomas said steam has been observed coming off the lava flow as it hits the ice. But he said the lava has not been melting a lot of ice, so there is not a perceived flood hazard.

 

 

http://juneauempire.com/state/2013-08-31/scientists-monitor-activity-veniaminof-volcano#.UiQ6z9K-2uI

[john pike]

Volcano Eruption in Guatemala on Monday, 02 September, 2013 at 18:33 (06:33 PM) UTC.

 

A phase of increased lava flow activity occurred this morning from about 6 am local time, generating a series of pyroclastic flows that descended several ravines on different, but mostly the southwestern side of the volcano. The volcano has been in moderate effusive activity for at least the past two weeks, feeding relatively small lava flows on the upper steep slope. A sudden increase in effusion rate seems to have caused the destabilization of the lava flows, generating rockfalls that turned into pyroclastic flows. The lava flows have quickly increased from previously 200 m to about 2 km length. The surge of magma supply is also suggested by the appearance of strong tremor pulses the previous night. In the meanwhile, explosive (strombolian) activity from the summit vent has remained weak. An ash plume rising as a by-product of the pyroclastic flows was reported to about 12,000 ft (3.6 km) altitude.

 

http://hisz.rsoe.hu/alertmap/site/?pageid=event_desc&edis_id=VE-20130902-40787-GTM

[john pike]

Volcanic activity worldwide 2 Sep 2013: Fuego, Veniaminof, Chirinkotan, Momotombo, Tolbachik

Monday Sep 02, 2013 19:04 PM |

Strombolian activity at Tolbachik on 30 Aug (photo: Volkstat.ru)

MODIS hot spot data (past 7 days) for Chirinkotan volcano (ModVolc, Univ. Hawaii)

Current seismic recording from Veniaminof (VNHG station, AVO)

Pyroclastic flows in the Ceniza canyon this morning (INSIVUMEH)

Seismic recording from Momotombo volcano (MOMN station, INETER)

 

http://www.volcanodiscovery.com/volcano-activity/news/36799/Volcanic-activity-worldwide-2-Sep-2013-Fuego-Veniaminof-Chirinkotan-Momotombo-Tolbachik.html

 

Tolbachik (Kamchatka): Although believed to have more or less stopped a week ago, it seems that weak eruptive has continued and regained some strength again now. Weak tremor has reappeared and incandescence could be seen again at the active vent at Tolbachinsky Dol at night. Tourists could observe strombolian activity and effusion of lava into the tube system on 30 August.

Chirinkotan (Northern Kuriles): Some eruptive activity has been continuing throughout the past month at the remote volcano in the Kuriles. Various satellite data collected during the months of August and September show the presence of a strong thermal signal (perhaps a lava lake) and a gas and steam plume, which might contain at least small amounts of ash.

The thermal signals were spotted on several occasions (when the usual dense cloud cover did not prevent it) during the month of August, which suggests that the eruptive activity has been continuous throughout the month.

Veniaminof (Alaska Peninsula, USA): Another phase of strong tremor started last night, probably corresponding to a second paroxysm with lava fountains and ash emissions. Bad weather conditions have been preventing direct observations.

AVO has received no reports of ash fall on nearby communities, but this remains a possibility as the elevated levels of seismic activity continue. (AVO)

Fuego (Guatemala): A phase of increased lava flow activity occurred this morning from about 6 am local time, generating a series of pyroclastic flows that descended several ravines on different, but mostly the southwestern side of the volcano.

The volcano has been in moderate effusive activity for at least the past two weeks, feeding relatively small lava flows on the upper steep slope. A sudden increase in effusion rate seems to have caused the destabilization of the lava flows, generating rockfalls that turned into pyroclastic flows. The lava flows have quickly increased from previously 200 m to about 2 km length. The surge of magma supply is also suggested by the appearance of strong tremor pulses the previous night.

... [read more]

Momotombo (Nicaragua): (1 Sep) The earthquake crisis has intensified today and developed into a swarm of shallow (around 5 km depth) earthquakes SE of the volcano. INETER reported already more than 30 quakes between magnitude 1-3 today.

There is no official statement available so far, although this might well be a precursor for a possible eruption in the near future.

[john pike]

 

 

http://juneauempire.com/state/2013-08-31/scientists-monitor-activity-veniaminof-volcano#.UiQ6z9K-2uI

 

 

http://www3.uni-bonn.de/Press-releases/devastating-long-distance-impact-of-earthquakes

 

Scientists at the University of Bonn simulate that seismic waves can be focused like in a parabolic reflector

In 2006 the island of Java, Indonesia was struck by a devastating earthquake followed by the onset of a mud eruption to the east, flooding villages over several square kilometers and that continues to erupt today. Until now, researchers believed the earthquake was too far from the mud volcano to trigger the eruption. Geophysicists at the University of Bonn, Germany and ETH Zurich, Switzerland use computer-based simulations to show that such triggering is possible over long distances. The results have been published in „Nature Geoscience“.

[john pike]

http://aolbroadband.welcomescreen.aol.co.uk/video/mysterious-mountain-fire-emitting-toxic-fumes-in-alaskan-town/517919340/

 

new volcano forming????????

[swebby]

http://aolbroadband.welcomescreen.aol.co.uk/video/mysterious-mountain-fire-emitting-toxic-fumes-in-alaskan-town/517919340/

 

new volcano forming????????

 

Think the balance of probabilities is for some kind of a burning oil/gas seep.  More about it here http://www.alaskadispatch.com/article/20130818/underground-fire-burning-remote-alaska-raises-concerns-about-toxic-gas

 

  reading through the comments at the bottom there is a suggestion that this may have been burning for some time.

Edited September 4, 2013 by swebby

[john pike]

On the evening of Sept. 1, the Ubinas Volcano in Moquegua registered two small eruptions. A third eruption occurred the following day, and now the volcano has errupted twice more, bringing the total to five eruptions in less than 48 hours. A number of news outlets have reported that the volcano's sudden burst of activity has caused alarm in the area, which has been intensified by the appearance of a column of volcanic gases and ash that has reached a height of two kilometers. Now scientists have begun an investigation at the site to determine the exact cause of the eruptions. Andina news agency reports that a team from the Volcanological Observatory of the Institute (OVI) of Geology, Mining, and Metallurgy has arrived in the area and scaled the mountain to search the crater site for clues as to its cause. Jersey Marino Salazar, head of the OVI team, told Andina: "We have two hypotheses right now, and in the coming days, through evaulations that we're doing, we'll find out what's really going on with Ubinas." He said that the explosions are probably being caused by one of two things: either the eruptions are phreatic, caused by precipitation buildup causing pressure inside the volcano, or they are caused by an "eruptive process generated by rising magma." According to Andina, the column of ash has deposited residue up to 10 kilometers away from Ubinas. However, Marino Salazar stated that the ash column does not pose a danger to people or livestock at this time, as the wind is blowing it towards a mostly uninhabited area. Still, Salazar may meet with local authorities on Sept. 4 in order to discuss any necessary actions.

[john pike]

Sakurajima eruptions time-lapse video 4 Sep 2013

 

Sakurajima volcano (Japan): large explosion damages cars

Wednesday Sep 04, 2013 16:49 PM | BY: T

Vulcanian explosion from Sakurajima this morning (JMA)

Damage to cars from this morning's eruption (JMA)

 

http://www.volcanodiscovery.com/sakurajima/news/36851/Sakurajima-volcano-Japan-large-explosion-damages-cars.html

 

 

Volcanic activity worldwide 4 Sep 2013: Etna, Karangetang, Ubinas

Wednesday Sep 04, 2013 13:54 PM |

MODIS hot spot data (past 7 days) for Karangetang volcano (ModVolc, Univ. Hawaii)

Etna (Sicily, Italy): A small ash emission was reported to have occurred yesterday morning from the New SE crater. This would likely be the first eruptive activity since the spectacular series of paroxysms in the first months of the year.

It could indicate that Etna is about to wake up again with more activity in the near future.

Karangetang (Siau Island, Sangihe Islands, Indonesia): A new eruption could be underway at the volcano. VSI raised the alert to 3 (Siaga, alert) on a scale of 1-4, following the observation of incandescent lava at the summit and glowing rockfalls on the eastern side into the Batuawang ravine. Strong degassing generates a plume rising up to 500 m.

Satellite images show a hotspot at the summit as well.

These observations suggest that new magma has been arriving at the summit where mild strombolian activity is taking place. If this activity increases, the occurrence of dangerous pyroclastic flows is a likely scenario, similar to what happened at Fuego volcano in Guatemala a few days ago.

Ubinas (Peru): The volcano woke up with a series of small ash explosions over the past days. The first and largest occurred on Sunday (1 Sep) and 4 smaller ones followed on Monday and Tuesday.

According to the scientists from Instituto Geofísico del Perú (IGP) the explosions were purely phreatic, i.e. driven by overheated steam following increased snowfall at the crater, and not related to the rise of new magma.

The new activity follows a similar event earlier this summer, when a pilot reported a small ash plume, which was the first observed activity since 2010.

 

A moderately large vulcanian explosion occurred this morning, producing significant fallout of lapilli and small bombs in several kilometers distance. Cars parked at the Arimura Lava observatory observation point to the south of the volcano were damages and windshields broken, at a distance of about 4 km. There are no reports of injuries to people.

The ash plume from the eruption rose to approx. 12,000 ft (3.6 km) elevation, i.e. about 2.5 km km height. In itself, today's explosion is not even among the largest that have occurred in the past months, but the volcano clearly continues to be in a state of elevated activity when seen on a long-term average. The following webcam time-lapse video shows frequent ash emission and explosions from the volcano today:

In a recent interview with Radio New Zealand, volcanologist Masato Iguchi mentions that the volcano might be heading for a larger eruption comparable to that of 1914:

“The magma level deep within the volcano is back to about 90% of what it was before the 1914 eruption. So we do have to worry about a big eruption in the long termâ€.

[john pike]

Largest Volcano on Earth Lurks Beneath Pacific Ocean

   

The world's largest volcano lurks beneath the Pacific Ocean, researchers announced today (Sept. 5) in the journal Nature Geoscience.

Called the Tamu Massif, the enormous mound dwarfs the previous record holder, Hawaii's Mauna Loa, and is only 25 percent smaller than Olympus Mons on Mars, the biggest volcano in Earth's solar system, said William Sager, lead study author and a geologist at the University of Houston.

"We think this is a class of volcano that hasn't been recognized before," Sager said. "The slopes are very shallow. If you were standing on this thing, you would have a difficult time telling which way was downhill."

 

 

Tamu is 400 miles (650 kilometers) wide but only about 2.5 miles (4 km) tall. It erupted for a few million years during the early Cretaceous period, about 144 million years ago, and has been extinct since then, the researchers report.

 

http://www.livescience.com/39447-biggest-volcano-earth-found.html

 

see link for full story