Ceramic Pressure-Tight Housings for Ocean-Bottom Seismometers Applicable to 11-km Water Depth

Ceramics have some outstanding features that are necessary for pressure-tight housings, such as higher compressive strength, lower specific gravity, and higher resistance against corrosion. One promising application is pressure-tight housings for a free-fall popup ocean-bottom seismometer (OBS). Ceramic pressure-tight housings can provide sufficient strength and buoyancy even at 11-km water depth. Nevertheless, tensile and bending strengths of ceramics are only a fraction of their compressive strength. For metals, they are almost equal. Therefore, common design methods for pressure-tight housings are not directly applicable to ceramic pressure-tight housings. As described herein, we propose a new design method for ceramic pressure-tight housings, particularly a method of reinforcement of through-holes for underwater connectors. We also present detailed data that support the proposed design method.