100-foot deep lake disappeared in Chile

A lake in Chile's southern Andes has disappeared and scientists want to know why.
Scientists in Chile are investigating the sudden disappearance of a 100 hundred foot deep glacial lake in the south of the country.When park rangers patrolled the area in the Magallanes region in March, the two-hectare (five-acre) lake was its normal size, officials say.

"The lake had simply disappeared.No one knows what happened," Juan Jose Romero, head of Chile's National Forest Service in the southernmost region of Magallanes, said.

In May 2007 they found a huge dry crater and several stranded chunks of ice that used to float on the water.

One theory is that an earthquake opened up a fissure in the ground, allowing the lake's water to drain through.

"In March we patrolled the area and everything was normal," said Romero.

"We went again in May and to our surprise we found that the lake had completely disappeared. All that was left were chunks of ice and an enormous fissure," he said.

Geologists and other experts are being sent to the area, which is some 2,000km (1,250 miles) south of the capital, Santiago, to investigate.

The region is shaken by frequent earth tremors and one idea is that a strong quake which hit the neighbouring region of Aysen in April opened up the fissure in the bottom of the lake.

A glacier specialist, Andres Rivera, told Chilean newspaper La Tercera that the lake's disappearance seemed to be part of the continual reforming of the landscape.

Also,the once plentiful river that flowed out of the lake was reduced to a trickle.The Magallanes area "has seen interesting changes in the last few decades," Rivera said, noting that the lake itself had not been there 30 years ago.

The lake, in the Magallanes region of southern Chile, was fed by a glacier but had radically dissapeared by the time researchers visited it in May,2007.

Locals have reported that the glacial lake had always existed, and through monthly patrols and photographic evidence it is clear the lake had remained relatively the same, independent of seasonal shifts in rain and snowfall,” reported Chile’s National Forestry Service (CONAF), which has monitored the area for the past three years.

“This is the first time our park rangers have recorded anything like this. However, we are not specialists, and we prefer not to speculate about the cause at this point,” said CONAF regional director Juan José Romero.

In July, a team of geologists and investigators will meet at the site to determine what exactly happened to the lake. Satellite images will also be examined.

Residents of the area blame the 6.2 magnitude earthquake which hit the neighboring Aysen region last April and caused over 50 landslides (May 22). They suggest that a rift opened up and drained the lake’s water.

Chilean glaciologist Gino Casassa, one of the 63 experts who participated in the second UN report on global warming, told the La Tercera newspaper that he believes the lake disappeared due to a relatively common glacial phenomenon: a Glacial Lake Outburst Flood (GLOF). A GLOF is a sudden increase in a lake’s volume due to one of various possible causes, including a volcanic eruption, an earthquake, an avalanche, or a portion of a glacier falling into the lake.

The GLOF broke open a tunnel of ice below the lake, which drained the water to the ocean. “In this zone in particular... we have evidence that, in general, the lakes are filling up as the glaciers melt,” Casassa said. Global warming is most likely responsible for this process, as well as for the increase in GLOFs.