GLOBAL VOLCANISM: The Volcano Report For March 27-29, 2014 – Major Updates On Reventador, Shishaldin, Grímsvötn, Hekla, Etna, Karkar, Batu Tara, Merapi, Marapi, Dukono, Ubinas, And Mount Hood!

March 29, 2014 – WORLDWIDE VOLCANOES – The following constitutes the new activity, unrest and ongoing reports of volcanoes across the globe.

Reventador (Ecuador): The volcano’s activity has remained high since the beginning of the current eruptive phase since 25 March. Fresh lava continues to extrude at the summit crater, adding to the dome that had been active since 2011, and producing incandescent avalanches, small pyroclastic flows on its flanks and ash emissions.

Overlaying of thermal and visible images showing the new lava flows on Reventador (image: F. Vásconez , IG)

Current seismic signal from Reventador (CONE station, IGPEN)

Seismic activity has remained at high levels, showing continuous tremor and emissions signals. IGPEN reports that the pyroclastic flows on the E, SE and S flanks have traveled up to 1.5 km from the summit. Additionally, there seems to be at least 2 lava flows that descend the south-eastern and eastern flank of the volcano, with fronts reaching approx. 500 m distance.

Shishaldin (Aleutian Islands, Alaska): After a week of unrest, Shishaldin Volcano in the Aleutians is being put on a higher alert level.  The Alaska Volcano Observatory reported Friday that there have been explosions inside the volcano and elevated surface temperatures since March 18.  AVO head scientist John Power says that appears to mean there’s been a small eruption.

Shishaldin Volcano with a typical steam plume, pictured on Sept. 14, 2013.
Photo by Joseph Korpiewski, U.S. Coast Guard.

“There is probably fresh magma or lava down inside the crater,” he said.

Power says there hasn’t been any lava seen on the rim of the crater or the sides of the volcano. Shishaldin also isn’t emitting any ash.

But Power says this could be a precursor to a bigger event.

“Little things happen like this happen at Shishaldin probably even more often than we’re able to detect,” he said. “They’re always, though – whenever you see some activity like this, there is a concern that it could, you know, escalate into something larger.”

He says Shishaldin is now on a “watch” alert level, which carries an orange color code. It had previously been on a yellow – or “advisory” level – since January.

Only one of the six seismic monitoring stations on Shishaldin is active right now. The others are offline, and there’s not enough funding available to repair them.”

Shishaldin is on Unimak Island, northeast of Unalaska. Of all the conical glacial volcanoes in the world, it’s the the most symmetrical. It’s also the Aleutian Islands’ highest peak, and one of the most active in the chain.

Its last big eruption was in 1999, when it sent an ash plume 45,000 feet above sea level. There hasn’t been any unusual activity there since 2009.

Grímsvötn (Iceland): A small jökulhlaup (glacier outburst flood) started yesterday from the subglacial lake Grímsvötn and has been discharging into the river Gígjukvísl.

Earthquakes under Grímsvötn volcano, probably a result of the glacial flood (Icelandic Met Office)

The event, which could have been triggered by normal fluctuations of hydrothermal activity under the ice is expected to be small. The Icelandic Met Office reports maximum discharge rates on the order of magnitude 1000 cubic meters per second, similar to rates during summer ice melt, and expects no damage to occur. The maximum of the flood is expected to be around the end of the week.

A small shallow earthquake swarm, probably as a result of adjustments in the ice mass above the draining lake, has accompanied the flood today. There are no indications that the flood was caused by a volcanic eruption of Grímsvötn volcano.

Hekla (Iceland): The volcano remains restless, but without any indication of an impending eruption (however, it is notorious for not giving much warning either).

Strain and earthquakes under Hekla volcano (Iceland Met Office)

3 tiny earthquakes, all below magnitude 2, occurred today and add to the ongoing series of occasional small quakes under the volcano.

Current GPS and strain (volume changes of the bedrock, a strong indicator immediately prior to an eruption, while magma is pushing upwards) measurements show no significant variations.

Etna (Sicily, Italy): During the night, the lava effusion and persistent mild explosive activity from the New SE crater ceased, after being nearly continuously active for over two months.

Etna’s New SE crater this morning (Etna Trekking webcam on Schiena dell’Asino)

If this is a true end or only a short pause to the latest eruptive phase which on 22 January remains to be seen. The tremor fell back to low levels in correspondence.

Karkar (Northeast of New Guinea): Several ash plumes at estimated altitude of 8,000 ft (2.4 km) were spotted during the past 2 days. This suggests a new eruptive phase could have started at the remote volcano.

Karkar volcano – no hot spot is visible on MODIS data.

Batu Tara (Sunda Islands, Indonesia): After a relatively long time with no spotted ash clouds, an ash plume was seen yesterday again on satellite imagery (VAAC Darwin).

The remote volcano in the Fores Sea has been site of continuing strombolian activity since at least 2006. Some of the eruptions are strong enough to leave ash plumes that can be seen on satellite images.

Merapi (Central Java, Indonesia): A possibly strong eruption was reported from the volcano this afternoon (13:55 GMT). Satellite data showed an ash and SO2 plume drifting SW at estimated 32,000 ft (9 km) (VAAC Darwin). The plume is quickly dissipating, suggesting that the eruption was an isolated (possibly phreatic) explosion.

Ash plume from Merapi in Centra Java (ESA)

No other details are at the moment available.

Marapi (Western Sumatra, Indonesia): The volcano erupted again yesterday afternoon at 16:15 local time, the volcano observatory post reported. It appears it was one of the largest explosions during the volcano’s current phase of activity.

Although the eruption was itself not visible due to cloud cover, the seismic signal showed a strong explosion that lasted 38 seconds and relatively “thick” ash fall occurred shortly afterwards in Batipuh and Tanahdatar districts until 17:45.

The alert level of Marapi remains unchanged at level II out of 4. Authorities recommend people to avoid a 3 km radius zone around the volcano.

Marapi has been in a phase of activity characterized by sporadic explosions of generally small size since 3 August 2011. Earlier eruptions this year, according to local press occurred as follows:

– 8 Jan: 2 explosions, ash plumes rising 700 m.
– 9 Jan: 5 explosions, ash rising up to 250 m
– 16 Jan: 5 small eruptions in the morning, but no visual observations.
– 19 Jan: one eruption that lasted 17 seconds.

Dukono (Halmahera): Activity at the volcano continues to be intense. An ash plume was reported extending 80 nautical miles to the west at 10,000 ft (3 km) altitude this morning (VAAC Darwin).

Ubinas (Peru): The volcano’s new lava dome continues to grow slowly within the crater. New field observations published yesterday in a detailed report showed that the lava dome is now approx. 120 m in diameter and has completely filled the inner pit left by the explosive activity in 2006 (as of 19 March). Visible glow (even in daylight) indicates very high temperatures.

The new lava dome with high-temperature degassing on 19 March (J. Acosta, Defensa Civil de Moquegua

No explosions have occurred since the vent-clearing explosion on 14 Feb, but the volcano emits a significant plume of steam, SO2 gas and sometimes dilute ash. On 21 and 23 March, the steam-gas-ash plume rose 1800 m above the crater.

On 25 March, light ash falls were reported in the towns of Querapi and Ubinas, as well as strong rumbling noises in distances up to 6 km SE.

Seismicity remains above background with frequent earthquake swarms related to internal fluid movements.
According to IGP, the intensity of the current activity overall is still low and probably continues for a while at similar levels, although explosions (caused, for instance, by trapped gasses under the lava dome) could occur at any time.

Mount Hood (Oregon, United States): A swarm of little earthquakes has been rumbling this week beneath Mount Hood, Oregon’s tallest peak, but geologists said there is no cause for alarm.

In this Oct. 2, 2013 file photo, clouds lift briefly and allow the sun to highlight Mount Hood wearing a fresh coat of snow
near Government Camp, Ore. A swarm of little earthquakes have been rumbling this week beneath Oregon’s tallest peak.
The 11,240 mountain is a mecca for skiers, hikers and climbers. It is also volcanic. But geologists say it is not about to
erupt. Tectonic plates are shifting inside the mountain, causing the little temblors. Geologists say it has happened
before and there is no cause for alarm. (AP Photo/Don Ryan, File)

Sensors have recorded nearly 40 tremors near Government Camp, an unincorporated community in Clackamas County, since Sunday morning, with the largest a magnitude 2.3, barely big enough to feel.
   
The 11,240-foot mountain is a mecca for skiers, hikers and climbers. It is also volcanic. But researchers say the recent quakes are normal activity and aren’t signs of volcanic activity, such as magma heating up and starting to flow beneath the mountain.
   
“No one should start to batten down the hatches,” said Ian Madin, chief scientist with the Oregon Department of Geology and Mineral Industries.
   
Mount Hood is in a chain of volcanic peaks, called the Cascade Range, stretching from Canada into California. The chain includes Mount St. Helens, just to the north of Mount Hood, which erupted violently in 1980 and last erupted in January 2008.
   
Geologists say the recent quakes on Mount Hood appear to be caused by tectonic plates shifting, possibly along a nearby fault line deep in the earth, as the Cascades slowly stretch. It’s a process that has been happening over millions of years.
   
Seismologist Seth Moran at the Cascades Volcano Observatory in Vancouver, Wash., said it’s not clear where exactly the quakes originated – they are small and deep, and there are not enough seismic stations in the area to pinpoint them – but he thinks most occurred near Government Camp. He said “bursty” swarms of small earthquakes under the mountain’s south flank are normal, but a large quake right under its peak or a sustained series of quakes that build in magnitude could be cause for alarm.
   
The quakes this week fit within the broad category of what is normal in the region, Moran said. Little quakes like these give scientists a better understanding of what that “regular state of being” looks like, he said. They can then compare the “normal” against activity that may be a precursor of greater threats.
   
Geologists say the last confirmed eruption of Mount Hood was more than 230 years ago, and it’s hard to predict when it will blow again.
   
Any of the volcanoes in the Cascades could erupt again “in our lifetimes,” Moran said.

Complete Earthquake list (worldwide) for March 29, 2014.
   

SOURCES: Volcano Discovery | KATU | Alaska Public Media.

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