A Three-component Ocean Bottom Microprocessor-based Seismometer

Ocean bottom seismometers (OBS) have been widely used during the last thirty years to collect seismic data for the determination of the structure of oceanic lithosphere and earthquake activity. Understanding the process of the creation of crust and lithosphere at mid-ocean ridges is a major goal of marine geophysics. Seismic refraction and reflection studies provide information on crustal structure. The distribution of earthquake activity in time and space contains information on the forces active in the spreading process. To achieve these important scientific goals, a number of research groups have developed ocean bottom seismometers (Ambuter and Solomon, 1974; Prothero, 1974, 1976, 1979, 1981; Johnson et al 1977; Mattaboni and Solomon, 1977; Sutton et al, 1977; Avedik et al, 1978; Latham et al., 1978; Heffler and Varret, 1979; Kasahara et al, 1979; Koelsch and Purdy, 1979; Moore et al, 1981; Kirk et al, 1982; Whitmarsh and Lilwall, 1983). Recent developments in electronic devices and improvements in battery design have allowed the ocean bottom seismometer to become an operational tool. Considerable flexibility is provided by using low-power microprocessors. So the instrument complexity has shifted from hardware that is difficult to modify to software algorithms. This paper describes a new instrument which uses current electronics technology to achieve significant improvements in performance. This instrument is the first one of a planned network which will be used by the French scientific community.