Detecting a Tsunami

animation of Indian Ocean tsunami propagation on rotating globe

Simulation of the Indian Ocean tsunami of 2004 generated by a 9.1 earthquake.

Seismic data can help determine the possibility of a tsunami. But how do we know if a tsunami is really occurring?

Question

If a tsunami is moving through the open ocean, far from any coasts, will anybody know? (Choose the best answer.)

The correct answer is a).

Oceans are huge, and it is not easy to detect a tsunami moving across such a large area, but tsunami scientists have come up with ways to detect tsunamis even thousands of kilometers from any coast.

Please make a selection.
map showing tide gauge and DART buoy locations for some the world's ocean basins and U.S. coastlines

Sea level gauges in open ocean and near ocean and lake coasts

The solution relies on technology, including instruments in the open ocean, near coasts, and aboard satellites.