|Tsunami warning system|
After almost 1 year of great Dec26 Tsunami, Now officials trying to install first Tsunami warning system in Indian Ocean by this 26 Dec 2005. So can we see know-how of a Tsunami warning system.
Main Objectives of Tsunami Warning System: -
Reduction in the loss of life and property in coastal communities.
Elimination of false alarms which results in high economic costs for unnecessary evacuation.
It consists of-
An anchored seafloor Bottom Pressure Recorder (BPR).
A companion moored surface buoy for real time communicate.
Bottom package(BPR): -
A typical tsunami 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 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.
Surface Buoy: -
It maintains a tight watch circle to keep the buoy positioned within the narrow cone of the acoustic transmission( with BPR) . Two downward looking transducers are mounted on the buoy bridle below the sea surface. These transducers are used for acostic link with BPR.
How it works!: -
The BPR monitors water pressure with good resolution and with 15 second averaged samples. An algorithm running in the BPR generates predicted water height values and compares all new samples with predicted values. Under normal conditions (no tsunami) the BPR sends data on hourly basis.If two 15-second water level values exceed the predicted values the system will go into the Tsunami Response Mode and sends high frequency data every 15 seconds.
Data is transmitted from BPR to the buoy via an acoustic modem, and data is then transmitted from the buoy to ground stations via satellites. Human resources or software in the Ground stations do quick analysis and give warning if any tsunami is found.
Main Use: -
As Tsunami waves speed is very less comapre with RF transition rates, in many cases we may have atleast 2-3 hours time to save life in the coastal areas before tsunami hit!
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