South Pole Seismograph Station QSPA
The geographic South Pole is a unique location for seismological
observations of the earth because of its location on the spin axis
of the Earth. Seismological observations at the South Pole began
in 1957 during the International Geophysical Year (IGY). The seismographic
instruments were periodically upgraded, but as they became increasingly
sensitive through the years, noise from the nearby station activities
became more and more troublesome. In order to achieve the lowest
possible background seismic noise conditions at South Pole, it became
necessary to install the seismometers at much greater distance from
cultural noise sources and at greater depth than they had been previously.
A study in 1997 indicated that high quality seismic observations
should be obtainable by installing the seismometers at a distance
of 5 to 30 km from South Pole Station and at a depth of 200 to 500
meters. Noise would be attenuated more for even greater distances
and depths, but there are significant logistical limitations. The
location finally chosen is 8 km from South Pole Station and 300
m below the surface.
To accommodate the new seismometers, ICDS was tasked to drill three
holes 12 inches in diameter to a depth of 300 m. This was accomplished
by coring with a 4" drill, then reaming the holes to 12"
in two stages. The primary work took two seasons under the direction
of lead drillers Louise Albershardt (first half of 2001-02) and
Terry Gacke (remainder of the project), assisted (for part or all
of the project) by drillers Bella Bergeron, Mark Albershardt, Matt
Pender, Mat Kausch, Jay Johnson, and Denise Braun; it was completed
early enough in January, 2003, for the US Geological Survey to install
their seismometers (at a depth of about 275 m) before the end of
the season. Kent Anderson of USGS served with the drilling crews
during both seasons as USGS coordinator. A third, reserve hole was
completed and instrumented in the 2003-04 field season.
The borehole seismic installation and vault installation at
QSPA are part of the South Pole Remote Earth Science and Seismological
Observatory (SPRESSO) within the Quiet Sector of the South Pole.
The performance of the QSPA has been beyond expectations -- it
is the seismically quietest station in the entire Global Seismographic
Network at frequencies above 1 Hz. Real-time data from QSPA may
be viewed at www.liss.org, and further information on the GSN
may be found at http://www.iris.edu/about/GSN/