Scientists propose undersea Internet cables could offer a cheap way to improve the detection of tsunamis. You can find more info at NewScientist.
Computer modelling by Nair's team shows that the electric field generated by the tsunami that struck south-east Asia in 2004 induced voltages of up to 500 millivolts. Their calculations show this is big enough to be detected by voltmeters placed at the end of the fibre-optic and copper cables that carpet the floor of the Indian Ocean. The work will appear in the journal Earth, Planets and Space.
The idea has its limitations, though. Cables would not reveal the exact location or direction of the tsunami, and you would have to subtract noise created by fluctuations in the Earth's magnetic field, tides and the cable itself to avoid misleading signals.