ON THE OSCILLATIONS OF OCEAN BOTTOM SEISMOGRAPHS EXCITED BY BOTTOM CURRENTS

Abstract

Experiments conducted by the Laboratory of Seismology, Institute of Oceanology, Russian Academy of Sciences showed that bottom currents excited free oscillations of ocean bottom seismographs (OBS) of the pop-up type. These oscillations can affect the seismic sensors, even when these are at some distance from the OBS vehicle. They interfere with the shapes of earthquake records, because signals due to seismic events also excite OBS oscillations at resonant frequencies. A current of 6 cm/s produces a noise with amplitudes above the dynamic range of OBS. Several mechanisms for the generation of this noise are discussed with recommendations for noise reduction.