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caonacl
04-07-2009, 10:35 PM
Earthquakes and Melting Ice

Tuesday, 07 April 2009 Trevor Williams

VIDEO at Bottom Link

http://www.greenmuze.com/images/stories/photos/blogs/eco-geek/ecomar09/ilulissatglacier.jpg Ilulissat Glacier (upper right), Greenland. Image courtesy of NASA Earth Observation.


When a glacier slides forward over the land it causes large stresses to build-up at the surface between the land and the ice, which, if the stresses are released quickly, can lead to minor earthquakes. At Ilulissat Glacier, in Greenland, they recorded earthquakes of magnitude 3 in the last few years.

Numerous studies suggest that the loss of land ice may lead to large, local earthquakes as a result of redistributing surface loads as the ice retreats.

The glacier fields in Alaska, Greenland and Antarctica compress the land under immense pressure loads that lock-in potential earthquake stresses. As the compressive stress is released by melting ice, there is more likelihood that other loads and stresses will become dominant and that these stresses will be released as earthquakes.

The average speed the Ilulissat Glacier moves is around 2meters per hour but has been recorded at over 3kilometre an hour during a ‘surge’, which is incredibly fast, according to information released by Dr. Corell, director of the global change program at the Heinz Center in Washington, D.C.

The glacier flow accelerates when it is lubricated by river water flowing though ‘moulins’, 10m (32ft) diameter holes in the ice, which create lakes under the glacier. With global warming the number of moulins on the world’s glaciers has increased dramatically.
The Ilulissat Glacier was declared a World Heritage Site by UNESCO in 1972, along with the Great Wall of China and the Pyramids of Giza but is a disappearing site. The glacier calves (gives birth to) icebergs where it enters the ocean. The glacier itself is 5km wide and 1.5km thick where it breaks up into icebergs. The average speed it moves is around 15km a year and it loses enough ice to provide London with fresh drinking water for a whole year. It is also the most active glacier in the northern hemisphere.

Each year, more glaciers are melting faster, and more glacier ice is entering the ocean, further increasing the sea level. If the 3km (2.9mile) thick ice sheet covering Greenland were to melt then the world’s oceans will rise 7 meters. Even a partial melt would greatly change every coastline on the planet.

Other effects will also occur, including changes in the ocean salinity as fresh water enters the oceans and the Atlantic Conveyer Belt that transports warm gulf waters from the Caribbean to Europe will slow down, reducing the ocean’s ability to circulate and absorb carbon dioxide.

Recent loss of ocean ice and accelerated glacier melt is a clear sign that further earth trauma is to be expected in Alaska, Greenland and Antarctica.
Resources

NASA Information: http://www.nasa.gov/home/hqnews/2004/jul/HQ_04252_glaciers.html (http://www.nasa.gov/home/hqnews/2004/jul/HQ_04252_glaciers.html)
Heinz Centre for Science, Economics and the Environment: http://www.heinzctr.org/ (http://www.heinzctr.org/)

The report: An Overview of the Science and National Security Interests of Climate Change in the Arctic (http://www.heinzctr.org/publications/PDF/Corell_House_Testimony_Mar_25_09.pdf). (http://www.heinzctr.org/publications/PDF/Corell_House_Testimony_Mar_25_09.pdf)
Trevor Williams is a University of Victoria Mechanical Engineering PhD candidate specialising in renewable energy, power grid modelling and plug-in hybrid electric vehicles. He has a bachelors in Aeronautical Engineering, a Masters in Management Science and over 23 years international experience in the space industry, having worked on Earth observation and telecommunications satellites.

http://www.greenmuze.com/blogs/eco-geek/1002-earthquakes-and-melting-ice.html