PDA

View Full Version : Disappearing lake in Chile


diggy
04-02-2008, 07:27 PM
How can a lake simply disappear?
by Jacob Silverman (http://science.howstuffworks.com/about-author.htm#silverman)




Sometime in May 2007, a glacial lake in southern Chile (http://science.howstuffworks.com/map-of-chile.htm) disappeared. Chilean surveyors reported in March that the lake was its usual size, 100 feet deep and covering an area around five acres. Located in Bernardo O'Higgins Park, in the southern Andes mountains, the lake is (was) rarely visited and didn't even have a name. When Chilean forestry officials arrived, they were surprised to find nothing more than "chunks of ice on the dry lake-bed and an enormous fissure" where the unnamed lake had once been [Source: The Guardian (http://howstuffworks.com/framed.htm?parent=disappearing-lake.htm&url=http://environment.guardian.co.uk/water/story/0,,2108796,00.html)]. Five miles away, a river that was once more than 130 feet wide barely flowed. What could cause such a massive disturbance to make an entire lake and much of a river disappear?



Global Warming Image Gallery (http://science.howstuffworks.com/enlarge-image.htm?terms=global+warming&gallery=1&page=0)
http://static.howstuffworks.com/gif/disappearing-lake-1.jpg (http://science.howstuffworks.com/enlarge-image.htm?terms=global+warming&gallery=1&page=0)
Photographer: George Wood / Agency: Dreamstime.com (http://howstuffworks.com/framed.htm?parent=disappearing-lake.htm&url=http://www.dreamstime.com)
Scientists were at first puzzled out how a glacial lake
like this one could abruptly disappear. See more
global warming pictures (http://science.howstuffworks.com/enlarge-image.htm?terms=global+warming&gallery=1&page=0).


Global warming (http://science.howstuffworks.com/global-warming.htm) seems to be the knee-jerk response lately whenever a dramatic environmental change is observed. Indeed, global warming is a big concern for lakes, as many bodies of water are experiencing receding water levels due to a combination of low rainfall and high temperatures. In the Magallanes province, where the lake is located, the Tempano and Bernardo glaciers are shrinking, and both of those glaciers contributed water to the lake. Experts like Gino Casassa and Andres Rivera, both glaciologists, point to global warming as the cause of the glaciers' melting. So global warming was immediately considered as a possible cause, but when investigating the lake, scientists considered several other possibilities.




One theory scientists considered was that an earthquake (http://science.howstuffworks.com/earthquake.htm) in the area opened a fissure in the earth (http://science.howstuffworks.com/earth.htm), which sucked down the lake. Southern Chile experiences hundreds of small earthquakes a year, and a fairly large tremor was detected on April 21. The fissure observed in the empty lake bed could have provided an outlet for the lake water to escape, much like a stopper being pulled from a sink.




A second possibility draws in part on global warming and the melting of glaciers (http://science.howstuffworks.com/glacier.htm). Glacial lakes often develop behind natural dams called moraines, which are made of ice. Once a moraine is broken, whether by an avalanche (http://science.howstuffworks.com/avalanche.htm), earthquake, warming or other event, water bursts through and the lake sometimes drains.


It took scientists several weeks before they were able to discover the answer because the site is very remote -- about 4,900 feet above sea level and 1,250 miles south of Chile's capital, Santiago. But in early July 2007, scientists got their answer.

An investigation has revealed that too much water was the problem. The melting Tempano and Bernardo glaciers filled the lake beyond the crater's capacity. The increased pressure broke the lake's moraine through which water flowed out, later ending up in the ocean. The lake is refilling as the chunks of ice on the lake bed melt, though Chilean scientists pointed out that global warming did have a serious effect. Glaciers naturally melt and reform, but warming is causing the Tempano and Bernardo glaciers to melt more than they should..

For some lakes, rapidly appearing or disappearing is part of a natural process. The lake in Chile did not exist 30 years ago, though, again, global warming is likely affecting the process. Some lakes, including many in Alaska (http://science.howstuffworks.com/map-of-alaska.htm) and Florida's (http://science.howstuffworks.com/map-of-florida.htm) Lake Jackson, go through a similar process regularly, disappearing and reappearing during certain seasons, or from year-to-year or decade-to-decade.




http://science.howstuffworks.com/disappearing-lake.htm

HANZO
04-06-2008, 07:01 PM
Where im from in Turkey, theres a lake which totally dryed out. last time i went which was 4 years ago, it was fine. apparently now in the space of 4 years 90% of the lake has dissapeared. global warming is the obvious blame, the lack of rain full in the area and the fact that the surrounding area is all farm land, and ppl need to water their crops. they drank up all the water in the lake.

atleast thats what i think caused it, the area is a known earthquake zone and there was a pretty large earthquake in the region in 2002. so that may have effected it in some way.

Olive Oil Goombah
04-06-2008, 07:46 PM
Global warming would result in higher sea levels.

KERZO
04-30-2008, 07:38 AM
the fact there was a fissure makes me think that the water must have fell through it. Theres loads of air pockets under the earths crust so it could have went there.

I'm sorry the break the news but nothing lasts forever..............nothing. All our cities, monuments, lakes, mountains and everything else will become dust on an empty planet at some point. aaawwww diddums