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December 10, 2005
Singing Icebergs
A few days ago scientists of the Alfred-Wegener-Institut found out that icebergs could sing. Although the frequency of these sounds is too low for the human ear the noise made by a large iceberg (30 x 50 km) could be recorded at the Neumeyer station in Antarctica. The scientists believe that the sounds are caused by the movement of water in crevices of the iceberg under high pressure. This leads to vibration of the walls. These vibration are very similar to those of vulcanic origin. Scientists now hope to be able to use these seismic vibrations for better prediction of the time of a vulcanic eruption in the future.
This note about the icebergs took me straight back into 1982 when I spent my summer vacation in Greenland and fell in love with icebergs at first sight. So much that I came back again the next summer. They are truly beautiful as you can see below.
A truly majestic specimen
Icebergs are fascinating things. They are all pieces of "debris" from a glacier which eventually make it to the sea. That means they also contain of certain amount of air entrapped in the ice. There's nothing like the popping sound of melting little iceberg cubes in your night cap whisky in front of your tent after a long day of hiking through a breathtaking landscape.
The fastest moving glacier is the Jakobshavn glacier on the west coast. In 1985 it moved about 6700 m/year (18 m/day). It slowed down to 5700 m/year in 1992, picked up speed again in 1997 reaching a travelling speed of 9400 m/year in 2000 and even 12600 m/year (34 m/day!). The tongue of the glacier reaches into a long fjord which is packed with ice.
Jakobshavn ice fjord in 1983, view to the East towards the glacier
The ice in the fjord gives an illusion of being a solid surface which could be easily crossed. This is not the case, however, there are quite big gaps and channels between the pieces of ice.
View to the West towards the sea
The fjord gets shallower towards its mouth which causes the icebergs to get stuck. Only when the pressure inside the fjord gets big enough because the glacier never stops pushing new bits into the fjord at the other end are the icebergs released into the sea. A number of them pops out at the same time and - viewed from the sea - make a most impressive "skyline".
Icebergs popping out of Jakobshavn fjord
Posted by Mausi at December 10, 2005 08:23 PM
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Comments
A fascinating sight and a beautiful one - but cold!
Posted by: The Gray Monk at December 10, 2005 08:18 PM