SEISMIC NOISE STRUCTURE AT THE NORWEGIAN SEISMIC ARRAY,
BERGEN UNIV (NORWAY) SEISMOLOGICAL OBSERVATORY
Pagination or Media Count:
Power spectral analysis in frequency-wavenumber space and coherence studies in lag space have shown that the noise recorded by the short period 12 sensor subarray at NORSAR is critically dependent on the weather situation in the North Atlantic Ocean. In addition to the low frequency noise from the west, there is observed 2 second microseisms from the Baltic Sea. Because of the non-isotropic noise, the coherence is usually strongly azimuthal dependent, being represented in lag space by ellipses. Time variations of the coherence by a factor of 5 are easily observed.