A killer surge of sea water racing across an ocean should, theoretically, generate an electrical current that ought to be detectable by existing undersea cables, say researchers.
The idea has been successfully modeled using what's known about the 2004 Indian Ocean Tsunami. It looks like the wave moving through the Earth's magnetic field probably generated a small electrical current. That, in turn, could be absorbed by undersea cables and ought to be noticed as a telltale power surge.
If so, then undersea cables could be a quick way to detect and monitor dangerous tsunamis in the open ocean.
"This should be seen as a technical demonstration paper," said Manoj Nair of the University of Colorado, referring to his paper in the February issue of the journal Earth, Planets and Space. "We have a long way to go."
According to Nair and his co-authors' model, the 2004 Indian Ocean Tsunami surging along, and interacting with the Earth's magnetic field as it went, should have induced a 500-millivolt (or half of one volt) electrical current in undersea cables.
Just how the electricity is generated harkens back to the 19th-century scientist Michael Faraday, who showed that water flowing through a magnetic field can induce a flow of electrons — a.k.a. an electrical current. Ocean water is particularly good at this because it is very salty, making it a better conductor of electricity as it flows through the Earth's magnetic field, Nair explained.
As for the cables that could absorb some of that electrical flow, they are the sorts used for telecommunications across oceans. Today's modern fiber optic cables would not, of course, carry the current, Nair said, but they could just if a bit of copper wire were added to them.
"We also have a network of of old copper cables all over the oceans that are no longer in use," he said. These could, theoretically become part of an array that is used to detect tsunamis.
Of course, even if a cable-based tsunami detection idea is proven in the real world, it will only be at best a small part of a larger system of buoys and other monitoring systems to keep people informed about tsunamis, Nair said.
In fact, there could be some drawbacks to even attempting to set up such a detection system, according to geophysicist Mark Everett of Texas A&M University.
"From a practical way of monitoring tsunamis, it has problems," Everett said. For instance, there may not be cables in the right places and there are big costs that go with laying more cables, as well as maintaining existing cables. There is also a big risk of false alarms and other difficulties, he said.
On the other hand, said Everett, what Nair and his colleagues have modeled could have other uses — such as for studying other sorts of flows, currents, tidal surges and even internal waves in the oceans.
"There are many other different sorts of flow that scientists would like to study," Everett told Discovery News. "That could lead to other applications in the future."