The movement of electrically conducting ocean water in the ambient geomagnetic field induces secondary electric and magnetic fields in the oceans. Ocean water transport is now routinely inferred from undersea cable voltage data. We try to answer the question whether the method could also be useful to detect tsunami. A barotropic shallow water model along with a three-dimensional electromagnetic induction code was used to predict the electric fields induced by the Indian Ocean Tsunami occurred on December 26, 2004. It is shown that the ocean flow related to the Indian Ocean Tsunami must have induced electric voltages of the order of plus or minus 500 mV across the existing submarine cables in the Indian Ocean. The electric fields induced by the Tsunami flow have strength within the range of plus or minus 10 mV/km, with enhancements along the main flow region and near the coasts and islands. Thus, making use of the in-service or retired submarine cables to measure the electric potential across oceans, it may be possible to detect water movement related to tsunami.