Nothing special about seismic activity in Antarctica

May 30, 2002

Mysterious as the frozen continent may be, Antarctica is no different from any other landmass when it comes to the frequency of earthquakes, according to Penn State geoscientists.

Antarctica is a huge continent the size of the United States and Mexico combined. In the past, only a few seismic recording stations monitored earthquake activities in Antarctica, compared to the thousands of stations spread throughout the rest of the world. Consequently, the number of recorded earthquakes has always been thought to be paradoxically small, says Dr. Sridhar Anandakrishnan, associate professor of geosciences.

"It was thought that perhaps Antarctica was different," says Anandakrishnan. "That it did not have earthquakes because somehow the ice on top of the rock suppressed the earthquakes and that the cold temperatures also contributed.

"Now we have data to show that that is not true. We did find significant earthquakes in West Antarctica," he told attendees today (May 30) at the spring meeting of the American Geophysical Union in Washington, D.C.

Anandakrishnan, working with Paul Winberry, graduate student in geosciences, analyzed seismic activity from six seismic stations covering an area a little over 300 miles on a side. The research was supported by the National Science Foundation.

"West Antarctica is a rift, an area that is pulling apart and regions like that are prone to earthquakes," says Anandakrishnan. "We put listening posts in an area where we expected to have seismicity and we saw a fair number of events."

What the researchers found were a significant number of small earthquakes. While large earthquakes can be detected at seismic stations all around the world, smaller ones are only recordable locally.

Recording and gathering data from seismic equipment in West Antarctica is not easy. Equipment must be able to withstand and operate in the extreme climate of the ice sheet. For three months, the sun shines 24 hours a day and the temperatures are similar to a northern U.S. winter with highs of 5 degrees Fahrenheit. During this time, the seismic stations operate on solar power.

During the winter months, when the wind blows, wind generators charge the batteries that supply the power to heat the stations and operate the equipment.

"One station operated the whole year round," says Anandakrishnan. "All the rest operated all summer and from 60 to 80 percent of the remainder of the year."

But recording the data is not the only problem. While in other parts of the world, data can be sent via satellite from distant locales, in Antarctica researchers must return to the seismic stations to download the information. Satellites do not move in convenient orbits to relay information from the stations to the researchers at home.

"All of the satellites are in the northern hemisphere," says Anandakrishnan."We have to go back every year to collect the data."

The researchers hope that better satellite coverage of the southern hemisphere will help with future work in Antarctica. While electronics do not really mind the cold, all things mechanical are adversely affected by the low temperatures. Regular computer disks do not operate well in the cold, but newer flash disks work better.

"The number and depth of earthquakes in an area are important," says Anandakrishnan. "They provide a lot of information about what is going on beneath the earth, the types of faults and how they are moving."

In an area where a sheet of ice covers the ground, information about tectonic activity could provide information not available in any other way.

Penn State

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