Polar scientists detect magnetic anomaly at lake

February 14, 2001, 01:59 PM AUCKLAND (AFP)

- Scientists have discovered a huge magnetic anomaly at Antarcticas Lake Vostok, a vast unseen freshwater lake that has been completely isolated from the rest of the planet for millions of years, the Antarctic Sun reports in its latest issue.

Vostok is the centre of an environmental debate as American scientists, led by the US National Aeronautics and Space Administration (NASA), want to drill into the lake three to four kilometres (two miles) under the ice.

The Russian station on the ice above the lake in 1983 measured the coldest ever temperature recorded on Earth -- minus 89 degrees C.

Antarctic Sun reports from the US base at McMurdo Sound that scientist Tom Richter of the US Support Office for Aerogeophysical Research flew back and forth over the lake for three weeks this summer, looking through the ice.

"You could just look (at the instruments) and see there was something interesting going on," Richter said. "There's rough, regular, rocky ground and then all of a sudden you could see some flat lake surface."

Researcher Michael Studinger said it was the first detailed image of the lake.

Radar showed the terrain below the flat ice changed from rolling plains on one side to mountains on the other.

The findings will help scientists decide whether the lake was created by erosion or if it was formed by changes in the earth's crust.

The Antarctic Sun says the evidence is a huge magnetic anomaly on the east coast of the lake's shoreline.

As the first flight crossed over to the lake's east side, the magnetometer dial swung suddenly.

Usually magnetic anomalies are much smaller and it takes some effort to distinguish the anomaly from normal daily changes in the magnetic field.

"This anomaly is so big that it can't be caused by a daily change in the magnetic field," Studinger said.

The size and extremity of the magnetic anomaly indicated the geological structure changes beneath the lake, and Studinger guessed it might be a region where the earth's crust is thinner.

The Washington-based Antarctica Project is calling on supporters to write to NASA-JPL urging them "to consider alternatives to endangering the oldest, most pristine lake in the world."