Climate change could cause quakes, eruptions.

This is interesting.  If just from a theoretical-mathematical perspective.  If a cubic meter of ice weighs a ton, then a cubic kilometer should weigh 1,000,000 tons.  How many cubic kilometers of glacial ice are there?  Who knows?  If the boxing day quake was caused by melting glaciers, things could get interesting.  Of course, this, like many speculative pieces offers little prooof.

If the freshwater lowers the salinity of the northern atlantic, and stops the conveyor belt bringing the warm water northward, then Europe could find the Glaciers expanding southward.

Printed from www.thesudburystar.com web site Saturday, July 08, 2006 -  © 2006  The Sudbury Star
Climate change could cause quakes, eruptions

Tuesday, July 04, 2006 - 11:00

Canada - (CP) -- So the warnings of harsher heat waves, stronger hurricanes and rising seas fail to impress. How about volcanic eruptions in the Arctic, or a tsunami off the coast of Newfoundland? The latest scientific discipline to enter the fray over global warming is geology.

And the forecasts from some quarters are dramatic - not only will the earth shake, it will spit fire.

A number of geologists say glacial melting due to climate change will unleash pent-up pressures in the Earth's crust, causing extreme geological events such as earthquakes, tsunamis and volcanic eruptions.

A cubic metre of ice weighs nearly a tonne and some glaciers are more than a kilometre thick. When the weight is removed through melting, the suppressed strains and stresses of the underlying rock come to life.

University of Alberta geologist Patrick Wu compares the effect to that of a thumb pressed on a soccer ball - when the pressure of the thumb is removed, the ball springs back to its original shape.

Because the earth is so viscous, the rebound happens slowly, and the quakes that occasionally shake Eastern Canada are attributed to ongoing rebound from the last ice age more than 10,000 years ago.

Melting of the ice that covers Antarctica or Greenland would have a similar impact, but the process would be accelerated due to the human-induced greenhouse effect.

"What happens is the weight of this thick ice puts a lot of stress on the Earth," says Wu.

"The weight sort of suppresses the earthquakes, but when you melt the ice, the earthquakes get triggered."

When a quake happens under water it can cause a tsunami. Wu said melting of the Antarctic ice is already causing earthquakes and underground landslides although they get little attention.

He predicted climate warming will bring "lots of earthquakes."

When the glaciers melt, the reliquified water causes sea levels to rise and increases the weight on the ocean floor, which could also have an effect on the grinding tectonic plates deep below the surface.

The Earth's crust is more sensitive than some might think. There are well-documented cases of dams causing earthquakes when the weight of the water behind a dam fills a reservoir.

Alan Glazner, a volcano specialist at the University of North Carolina, said he was initially incredulous when he found a link between climate and volcanic activity off California.

"But then I went to the library and did some research and found that in many places around the world, especially around the Mediterranean, they see similar sorts of correlations."

"When you melt glacial ice, several hundred metres to a kilometre thick ... you've decreased the load on the crust and so you've decreased the pressure holding the volcanic conduits closed.

"They're cracks, that's how magmas gets to the surface ... and where they hit the surface, that's where you get a volcano."

No one has claimed that the Christmas tsunami of 2004 was triggered by rising sea levels. But that event seems to have sparked new interest in climate and geology.
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