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Seismic investigations are mainly limited by seismic noise. Two microbarometers have been installed in the seismic vault of two different GEOSCOPE stations, one at SSB and the other at TAM. All vertical components and most of the horizontal components show a significant correlation with pressure. In order to correct the seismic signals from the atmospheric 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 between the two stations, and the vertical components display noise levels below the low-noise model as defined by Peterson (1993). This technique reduces part of the noise and allows detection of small earthquakes and a better extraction of normal modes. The analysis of the lowest normal modes of the Earth excited by the MS = 8.2 Macquarie Island earthquake is given to illustrate the perspectives of the method.

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We describe the scientific purposes and experimental set-up of an international deployment of a 3 component broadband seismometer package on the ocean floor in Monterey Bay which took place during the summer of 1997. Highlights of this experiment were the installation, performed using a remotely operated vehicle (ROV), the underwater connection of the different components of the package, and the successful retrieval of 3 months of broadband seismic and auxiliary data. Examples of recordings of teleseisms and regional earthquakes are presented and the background noise characteristics are discussed, in comparison with those of near-by broadband land sites, current-meter data from the vicinity of the ocean bottom package, as well as pressure data from deeper ocean sites.