What are the five signs a tsunami is coming?

Signs of an Impending Tsunami

Natural warnings of an approaching tsunami can include:

• A strong or prolonged earthquake
• A loud noise resembling a train or airplane emanating from the ocean
• Uncharacteristic ocean behavior

The sea may appear as if it is quickly inundating the land, creating a fast-rising flood or forming a towering wall of water. Alternatively, the ocean could suddenly recede, exposing the seabed, reefs, and marine life much like an exceptionally low tide.

Source: FEMA - Tsunami | Signs and Clues