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THE Volcano Thread Pt. 2

Re: THE Volcano Thread Pt. 2

Unread postby vox_mundi » Sat 25 Nov 2017, 10:51:18

Climate Change Could Increase Volcano Eruptions

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Shrinking glacier cover could lead to increased volcanic activity in Iceland, warn scientists.

Dr Graeme Swindles, from the School of Geography at Leeds, said: "Climate change caused by humans is creating rapid ice melt in volcanically active regions. In Iceland, this has put us on a path to more frequent volcanic eruptions."

The study examined Icelandic volcanic ash preserved in peat deposits and lake sediments and identified a period of significantly reduced volcanic activity between 5,500 and 4,500 years ago. This period came after a major decrease in global temperature, which caused glacier growth in Iceland.

Dr Swindles said: "The human effect on global warming makes it difficult to predict how long the time lag will be but the trends of the past show us more eruptions in Iceland can be expected in the future.

Study co-author, Dr Ivan Savov, from the School of Earth & Environment at Leeds, explains: "When glaciers retreat there is less pressure on the Earth's surface. This can increase the amount of mantle melt as well as affect magma flow and how much magma the crust can hold.

"Even small changes in surface pressure can alter the likelihood of eruptions at ice-covered volcanos."

Open Access: Graeme T. Swindles et al. Climatic control on Icelandic volcanic activity during the mid-Holocene, Geology (2017).

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“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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Re: THE Volcano Thread Pt. 2

Unread postby Subjectivist » Sat 25 Nov 2017, 11:37:49

Any increase from isostatic rebound would be a very temporary conditin, not a permanent change. All glacier weight does is increase the pressure needed for the magma to break through to the surface. Take away the extra weight and a series of eruptions will relieve the extra presssure, then things return to the long term average time between build ups and eruptions a the lower pressure level.
II Chronicles 7:14 if my people, who are called by my name, will humble themselves and pray and seek my face and turn from their wicked ways, then I will hear from heaven, and I will forgive their sin and will heal their land.
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Re: THE Volcano Thread Pt. 2

Unread postby dohboi » Sat 25 Nov 2017, 12:01:13

But in the mean time, it is yet another feedback...
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Re: THE Volcano Thread Pt. 2

Unread postby rockdoc123 » Sat 25 Nov 2017, 12:10:37

The plot showing average number of volcanoes per decade is misleading for two reasons, 1. the vast majority of volcanic eruptions during this period are nowhere near an ice sheet and 2. the plot is more a measure of communication increase given there could have been lots of volcanic eruptions at the start of this time cycle that were not reported.

Periods of increased vulcanism are generally associated with change in tectonic plate motion, faster spreading rates can mean increased melt in subduction zones followed by increased upwelling and resultant vulcanism.

Something else that is incorrect here is that removing ice results in isostatic rebound so crustal rocks that were at a depth where partial melt occurs would now be at a level where partial melt is no longer occurring in effect stabilizing rock surrounding any mantle plume. Overburden pressure is less of a controlling factor than the presence of an expanding magma chamber where generated pressures are magnitudes higher than overburden pressure. As Sub points out any pressure imbalance caused by the removal of ice would be short lived with equilibrium occurring almost immediately.
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Re: THE Volcano Thread Pt. 2

Unread postby dohboi » Thu 30 Nov 2017, 17:46:46

More context:

Could Mount Agung cause global cooling effects lasting for years?


https://www.accuweather.com/en/weather- ... s/70003412

How could the Agung volcano in Bali affect global temperatures?

https://www.skepticalscience.com/how-co ... temps.html

Further:

Agung's recent activity matches the build-up to the earlier disaster, which ejected enough debris - about a billion tonnes - to lower global average temperatures by around 0.3°C for roughly a year.


http://www.channelnewsasia.com/news/asi ... ok-9454396

(Prepare for ignorant howls from the denialoosphere that 'GW is Over (and was hoax anyway)...blah, blah, blah')
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Re: THE Volcano Thread Pt. 2

Unread postby vox_mundi » Thu 07 Dec 2017, 11:31:15

Dangerous Iceland Volcano Oraefajokull May Be About to Erupt for First Time Since 1728

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The Oraefajokull (err-IVER'-yer-kuhl) volcano, dormant since its last eruption in 1727-1728, has seen a recent increase in seismic activity and geothermal water leakage that has worried scientists. With the snow hole on Iceland's highest peak deepening 18 inches (45 centimeters) each day, authorities have raised the volcano's alert safety code to yellow.

Experts at Iceland's Meteorological Office have detected 160 earthquakes in the region in the past week alone as they step up their monitoring of the volcano. The earthquakes are mostly small but their sheer number is exceptionally high.

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http://en.vedur.is/about-imo/news/monit ... aefajokull
Volcanologist Ármann Höskuldsson says that the situation at Öræfajökull volcano is "Far from normal." There's still geothermal heat in the area and the caldera has deepened by some 20 metres.

A 3-D image made by specialists at the Geological Institute of the University of Iceland indicates that the caldera has deepened by twenty metres and that crevasses have become larger since it was first spotted.


Öræfajökull hasn‘t erupted for nearly 300 years, but recent weeks have shown increased activity in the area. A new caldera emerged in the glacier nearly two weeks ago.

In 1362, the volcano erupted explosively, with huge amounts of tephra being ejected. The district of Litla-Hérað was destroyed by floods and tephra fall. More than 40 years passed before people again settled the area, which became known as Öræfi. The name literally means an area without harbor, but it took on a meaning of wasteland in Icelandic.

What worries scientists the most is the devastating potential impact of an eruption at Oraefajokull.

Located in southeast Iceland about 320 kilometers (200 miles) from the capital, Reykjavik, the volcano lies under the Vatnajokull glacier, the largest glacier in Europe. Its 1362 eruption was the most explosive since the island was populated, even more explosive that the eruption of Italy's Mount Vesuvius in 79 A.D. that destroyed the city of Pompei.

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Oraefajokull at lower center, near coast

To remedy the lack of data for Oraefajokull, scientists are rushing to install new equipment on and around the volcano. Those include ultra-sensitive GPS sensors that can detect even the slightest tremors, webcams for real-time imagery of the volcano and sensors in the rivers that drain the volcano's glaciers to measure the chemical composition of the water.

Associated Press journalists last week visited scientists working near the mouth of the Kvia River, where the stench of sulfur was strong and the water was murky, clear signs that geothermal water was draining from the caldera.

... If an evacuation is ordered, everyone in the area will receive a text message and the radio will broadcast updates. Police are confident that Oraefi's 200 residents will know how to react, but their biggest concern is contacting tourists.
"Some farmers may have only 20 minutes (to leave)"

"The locals know what to do. They know every plan and how to react. But the tourists, they don't," said Police Chief superintendent Sveinn Runarsson. "That's our worst nightmare."
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

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