The number one warning sign of a tsunami in Australia is the advice you may receive from the media (on radio or television) or from police and other emergency services. Follow their instructions immediately. The following are natural signs of a tsunami that you may, but not always, experience when you are near the coast in Australia or overseas. If you notice any of these three warning signs take action. • A shaking of the ground in coastal regions may reflect the occurence of a large undersea earthquake nearby that may generate a tsunami. • As a tsunami approaches shorelines, the sea may, but not always, withdraw from the beach (like a very low and fast tide) before returning as a fast-moving tsunami. • A roaring sound may precede the arrival of a tsunami.