Most people are aware of and understand the concept of seismology and seismographs. First developed in the early 2nd century B.C. by a Chinese philosopher, they have grown more advanced and sensitive over the years. They are most commonly used on land, and though they do provide warning of impending earthquakes, they are not effective for marine fault measurements, and thus cannot predict tsunamis.
Earthquake detection does not end with seismographs as one might think but rather involves Tsunameter stations recently established near marine fault zones that measure changes in water pressure at great depths, a common symptom of the proximal earthquakes. Tsunameters report evidence of passing tsunamis via satellite to nearby Tsunami Warning Centers and the Pacific Marine Environmental Laboratory. Scientists working there compare information regarding the earthquakes that spawned the tsunami with the data from the Tsunameters to disseminate warnings to threatened coastal areas.
The system consists of a buoy platform containing the control unit, modem, RF, GPS, and GOES antennas. A swivel chain and nylon cord attaches the above water system to the anchor near the sea floor. This latter station takes most of the readings with a Digiquartz Pressure Transducer recording the bottom pressure, a glass ball floatation reading direction and force of wave movement, and other sensors variable with each station that deliver data to a CPU.
An acoustic release transmits the data to transducers on the base of the surface buoy that relays it to the MasterControl Unit, broadcasting it to ground processing centers. Data dissemination systems that function with the speed of a cell phone call afford a warning time of only a few hours, and earthquake detection systems on land provide little augmentation to this narrow time frame.