Underwater sound waves may provide earlier tsunami warnings
When tsunami-triggering events such as underwater earthquakes occur, sound waves known as acoustic gravity waves (AGWs) are sent out through the water. Now, scientists from Cardiff University have developed a method of mathematically analyzing those waves, to predict how destructive the tsunami will be.
AGWs travel over 10 times faster than the tsunami itself, and move out in all directions from the epicenter of the earthquake.
When they're detected by even a single underwater hydrophone, it's possible to determine quake characteristics such as its location, duration, dimensions and orientation. By analyzing that data, the Cardiff researchers are now also able to calculate the amplitude and potential destructive force of the accompanying tsunami, far earlier than was previously possible.
Currently, warning systems consist of buoys that measure pressure changes in the ocean caused by tsunamis. If these devices are anchored relatively close to the shore, however, they don't provide much of an advance warning – the actual tsunami has to physically reach them in order to be detected. Additionally, a network of many buoys located around the world is required, which is expensive.
An AGW-based system wouldn't have such drawbacks.
"By taking measurements of acoustic gravity waves, we basically have everything we need," says lead scientist Dr. Usama Kadri. "Our aim is to be able to set off a tsunami alarm within a few minutes from recording the sound signals in a hydrophone station."
In a previous study, Kadri has also looked at the possibility of using artificially-generated AGWs to stop tsunamis from making landfall.
Source: Cardiff University
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