Figure 9. Prototype bottom-hole assembly about to be installed in a 200-m-deep water-filled hole south of Tokyo, Japan. The lowermost sensor is the strainmeter, followed by the Guralp broad band seismometer, an Applied Geomechanics tiltmeter, and a PMD broad-band seismometer. The tube linking the sensors is used to transport cement from the drill pipe through the strainmeter body and up around the whole assembly, thus anchoring it firmly to bare rock at the bottom of the hole.