NOAA Deep-ocean Assessment and Reporting of Tsunamis
Bottom Package

A typical tsunami DART bottom package mooring consists of a Bottom Pressure Recorder, an acoustic modem, acoustic release unit and battery pack bolted to a platform, to which a disposable anchor, flotation, and recovery aids are attached.
Moorings are designed to free-fall to the bottom and are deployable for 24 months at depths of 6000 m; recovery is initiated by triggering the acoustic release to separate from the anchor, at which point the flotation brings the unit to the surface.
These systems have measured tsunamis characterized by amplitudes less than 1 cm in the deep ocean, using a quartz crystal pressure transducer that is sensitive to changes corresponding to less than a millimeter of equivalent sea level change in the tsunami frequency band.

Block Schematic pdf

Mooring Diagram pdf

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