New borehole instruments for the South Pole

January 07

A new-generation CMG-3TB instrument with adaptations for cold conditions is headed for the South Pole as part of a major upgrade to the world’s quietest seismic station.

Station QSPA is located in the ‘Quiet Sector’, 8 km from the Pole, reserved as part of the South Pole Remote Earth Science and Seismological Observatory (SPRESSO).

In the three years since it was commissioned, the existing CMG-3TB borehole instrument at QSPA has consistently showed data intervals with minimum noise levels up to 12 dB below the Peterson (1993) Low Noise Model at 3 Hz, making the site among the quietest ever measured.

This sensor is to be replaced with an array of borehole instruments, which will have the potential to provide researchers with data of unequalled resolution.

A trial instrument of the new type is now ready for installation and on-site testing. It is expected to be fully operational in time for the launch of International Polar Year 2007–08, a global coordination of research projects focusing on the polar regions.

Noise levels measured at the existing QSPA station.


The new instrument is specially designed for installation in extremely cold environments, and is capable of operating at −60 ° C.

At 82 mm diameter, the sensor stack is one of the slimmest yet produced, improving the logistics of installation. Because the instrument does not require heating to keep it within its operational limits, the power requirements of the new sensor are significantly lower than the standard 3TB. This is an especially important consideration at the South Pole, where available power is strictly budgeted.

A programmable microcontroller manages sensor state-of-health ad mass control operations, using temperature-dependent internal settings to ensure reliable operation at all times. The microcontroller can be accessed from a standard RS232 serial port on the breakout box.


Seals and fixings throughout the sensor are chosen for their high performance at low temperature. The instrument can be flushed with inert gas prior to installation, excluding water vapour from the internal components.