Pacific Tsunami Observation Program (PacTOP)

Project Description
High-quality bottom pressure recorder ( BPR ) measurements in the deep ocean contribute to a fundamental understanding of oceanographic processes over a wide range of time scales. These vary from long-period fluctuations induced by planetary waves, oceanic tides, and meteorological forcing events, to relatively shorter-period phenomena such as long surface gravity waves, microseisms, and tsunamis. To capture these events, several types of transducers have been incorporated into pressure sensor units designed for oceanic applications. The most common types include the vibrating wire, strain gauge, quartz-resonator, Bourdon tube, and various capacitance devices. Vibrating wire designs typically correlate vibrational frequency with pressure-induced mechanical motion (Lefcort 1968; Vitousek and Miller 1970). Capacitance plate transducers such as those described by Harris and Tucker (1963) incorporate parallel capacitance plates in which the distance between plates varies as a function of applied pressure. Capacitance is inversely proportional to the plate gap and acts to tune an LC oscillator.

http://nctr.pmel.noaa.gov/eble1991.html