Tsunamis: warning signs
Signs in the deep sea
As we have seen in the previous pages, in the deep sea the height of a tsunami from trough to crest can be only about 3 feet tall (1 meter) because the bulk of a tsunami lies beneath the sea surface. As a consequence, tsunamis are hard to detect when they travel across the open ocean and they can arrive completely unexpectedly.
A network of deep-sea sensors would be needed worldwide to detect tsunami movement within the ocean, but that is not easy to implement. Creating the monitoring and communications infrastructure needed to issue timely warnings is a huge task presenting considerable problems, particularly for the poorest areas of the world.