Final answer:
A tsunami is a series of sea waves caused by an underwater earthquake, landslide, or volcanic eruption. The Great Tsunami of 2004 was caused by an earthquake off the coast of Sumatra and resulted in a high casualty count.
Step-by-step explanation:
A tsunami is a series of sea waves caused by an underwater earthquake, landslide, or volcanic eruption. Tsunamis can travel at speeds up to 700 km/hr and may be less than 30 cm high on the ocean's surface in deep water. As they approach shallow water near the coast, they slow down and the top of the wave moves faster than the bottom, causing the sea to rise dramatically, sometimes as high as 30 m.
The Great Tsunami of 2004, also known as the Indian Ocean tsunami, was caused by an earthquake off the coast of Sumatra. It had the energy equivalent of 23,000 atomic bombs and resulted in killer waves that crashed into the coastlines of 11 countries, causing immense devastation and a death toll of 283,000 people.