THE EFFECTS OF THE ATMOSPHERIC-PRESSURE CHANGES ON SEISMIC SIGNALS ORHOW TO IMPROVE THE QUALITY OF A STATION

Seismic investigations are mainly limited by seismic noise. Two microb arometers have been installed in the seismic vault of two different GE OSCOPE stations, one at SSB and the other at TAM. All vertical compone nts and most of the horizontal components show a significant correlati on with pressure. In order to correct the seismic signals from the atm ospheric pressure noise, a transfer function between the pressure data and the seismic data is inverted. Results show that, after correction , the noise levels reached on the horizontal components are similar be tween the two stations, and the vertical components display noise leve ls below the low-noise model as defined by Peterson (1993). This techn ique reduces part of the noise and allows detection of small earthquak es and a better extraction of normal modes. The analysis of the lowest normal modes of the Earth excited by the M(S) = 8.2 Macquarie Island earthquake is given to illustrate the perspectives of the method.