Seismic Noise Trapping in Firn

A comparative analysis was performed on datasets from two Global Seismographic Network (GSN) stations near the South Pole, Antarctica. The results of this analysis are provided and show that there is significant reduction of the background seismic noise generated by the activities at the Amundsen-Scott South Pole Station as a function of distance and depth. Data gathered from site selection work for a new station at South Pole revealed that the near surface firn layer, having a sharp velocity gradient, tends to turn seismic energy generated on the surface, back towards the surface, thus trapping the noise in the upper most layer. The new seismic station installed below this layer exhibits substantial reductions in noise levels in both high frequency (> 1Hz) and long period (> 10 sec) bands. Noise levels in the high frequency band are below the Peterson Low Noise Model making this the quietest station in the entire network in this band.