By Sid Perkins
New seismometers near the South Pole reveal that the area is the quietest spot on the planet for eavesdropping on earthquakes. Scientists hope the remote instruments, first turned on in mid-January, will pick up quake signs that are drowned out by the cacophony of civilization in other parts of the world.
Researchers have operated seismic instruments at the South Pole since 1957, says Scott Borg, a geologist at the National Science Foundation in Arlington, Va. The previous observatory was located about a football-field-length away from the other
Antarctic scientific facilities and 6 meters underground. That site wasn’t ideal because the instruments picked up vibrations from the throbbing generators of a small power plant, as well as from construction and other activities. Also, the shuddering of windblown antennas and buildings at the research base sent tremors through the surrounding terrain.
To minimize those sources of seismic noise, scientists placed the new observatory about 8 kilometers from the polar facilities and put the seismic sensors at the bottom of 300-m-deep boreholes. Last week, Borg and his colleagues released analyses of data obtained during the facility’s first 2 months of operation.
At the new location, seismometers can discern ground vibrations one-hundredth the size of those that could be distinguished from seismic noise at the old observatory. That’s also about one-quarter the size of vibrations detectable anywhere else in the world. In fact, it’s so seismically quiet at the new site that on quiet Sundays, instruments can detect ground vibrations from snowmobiles 8 km away.
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