POLARIS was an underground experiment to observe seismic signals at depth in very hard rock. It was carried out at SNOLAB, and underground physics laboratory, in Sudbury, Ontario. In addition to academic research, the data generated in the POLARIS experiment was used by the Canadian National Data Centre (CNDC) for earthquake, and nuclear explosion (see Partial Nuclear Test Ban Treaty) monitoring.
Background
SNOlab is an underground physics lab situated deep in the Creighton Mine, a 2 km deep Nickel mine operated by the Vale Limited. The mine is situated in the Sudbury Basin: a large impact crater on the Canadian shield.
References
POLARIS (seismology) Wikipedia(Text) CC BY-SA