Undersea fiber-optical cables may be able to detect coming tsunamis through changes in the Earth’s electromagnetic field, a recent study led geomagnetists at the University of Colorado has found.

The study found that during a tsunami, the charged particles in the ocean water interact with Earth’s magnetic field inducing a voltage of up to 500 millivolts in the cables used for the internet, reported Wired.com yesterday. The findings pave the way for the development of a relatively simple technology that might provide tsunami-warnings for nations that cannot afford other types of sensors.

“What we argue is that this is such a simple system to set up and start measuring,” said Manoj Nair, the scientist who headed up the study. “We have a system of submarine cables already existing. The only thing we probably need is a voltmeter, in theory.”

Nair and his team developed computer models to estimate the size of an electric field created by the force of the 2004 Indian Ocean tsunami as it moved over cables on the seabed. Salty water, a good conductor of electricity, generates an electric field as it moves through Earth’s geomagnetic field, explained a note in the National Oceanic and Atmospheric Administration website.
“We estimate that the 2004 tsunami induced voltages of about 500 millivolts (mV) in the cables. This is very small compared to a 9-volt battery, but still large enough to be distinguished from background noise on a magnetically quiet day,” said Nair.

Monitoring voltages across the network of submarine cables might enhance the current tsunami warning system, which relies on a global seismometer network to detect earthquakes that may indicate that a tsunami has formed.

Nair cautioned that his research, which will be published in February’s Earth, Planets and Space, is a novel idea that still needs to be tested and verified by other scientists. The main issue, he added, will be the effective isolation of tsunami signals from noise sources.

Devastation from the 2004 tsunami. Photo credit: Austcare