Braving the frigid wind, which seems to come straight from the North Pole, and temperatures around minus 30 degrees Centigrade, an engineer from Guralp Systems recently installed a specially fitted CMG-3T borehole sensor on the ice sheet in central Greenland. Similar models of such “Polar CMG-3T” sensors are already being used in Antarctica, both on the surface and in boreholes (see elsewhere on this website).
During the latest installation near Raven Camp just South of the Arctic Circle, our engineer cooperated with personnel from the US based IRIS consortium. Raven Camp can only be reached by a 40 minute flight in a converted military transport plane from the coastal town of Kangerlussuaq. The purpose of installing the broadband sensor in a borehole drilled 360 meters deep into the Greenland ice is many-fold. Scientists want to measure the rumble caused by calving events when giant icebergs break off the tongue of glaciers. In addition, the sensor will pick up the seismic noise generated when the ice sheet slowly moves over its rocky base. The intensity and frequency of these so called glacial quakes might even be used as an indicator of pending climate change.
It takes quite a few modifications to make our regular CMG-3T seismometers fit for long time fault free operations under the extreme conditions in the permanently glaciated regions in the highest latitudes. To offer sensors for such niche markets and invest in the necessary research and development is one of the strengths which sets Guralp Systems apart from other purveyors of seismic instruments.
Power to the installation comes primarily from photovoltaic panels and a battery of cells having sufficient capacity to maintain the systems during the three months of darkness. A small wind-turbine augments the solar array. The reflectivity of the ice allows the solar panels to run at maximum output whenever it is light.
