Tuesday, August 21, 2012

OCEAN TIDES SHAKE UP ANTARCTICA

Thousands of earthquakes occurring in rapid succession in less than a year under an Antarctic glacier may have been linked to ocean tides, new research suggests.

Scientists investigated seismic activity under David Glacier, a large glacier in East Antarctica about 270 square miles (700 square kilometers) in size. The glacier serves as the outlet from which ice from 4 percent of that region's ice sheet drains out toward the sea.

To learn more about the foundations and behavior of this glacier, the researchers analyzed seismic data gathered from there over a nine-month period between 2002 and 2003 by the Transantarctic Mountains Seismic Experiment array of 42 seismometers. They identified about 20,000 seismic events during this period that were stronger and lasted longer than the shaking typically seen with glaciers.

"The fact these events exist is fairly surprising," researcher Lucas Zoet, a glaciologist at Pennsylvania State University, told OurAmazingPlanet. "This type of seismic behavior had not been observed before in Antarctic outlet glaciers, so one main challenge was just to categorize it initially." Read More