Tsunamis Reading Comprehension Lesson

What Is a Tsunami?

A tsunami is one of the most powerful and destructive natural disasters on Earth. The word “tsunami” comes from Japanese and means “harbor wave.” Tsunamis are giant ocean waves that form after a sudden disturbance occurs under the water — most often an underwater earthquake. Erupting volcanoes and underwater landslides can also trigger tsunamis. Once formed, the waves spread outward in all directions from the point of origin, like ripples when a stone is dropped into still water.

Tsunamis begin as an underwater earthquake shifts large sections of the ocean floor. The movement of the earth displaces enormous amounts of water, sending powerful waves racing toward the shore. In the open ocean, these waves may be only a few feet tall and barely noticeable to a passing ship. But as the waves approach shallow coastal water, they slow down and pile up on top of each other, growing to incredible heights. Some tsunami waves have reached heights of 100 feet or more when they come ashore.

Tsunami waves can travel across the open ocean at speeds of up to 500 miles per hour — about as fast as a jet airplane. Because of this enormous speed, a tsunami generated thousands of miles away can still strike a coastline with devastating force. Warning systems have been developed around the Pacific Ocean and other areas to detect tsunamis early and give coastal communities time to evacuate before the waves arrive.

Destructive Tsunamis in History

Throughout history, some of the most powerful tsunamis have caused enormous loss of life and property. In 1946, a tsunami struck the coast of Hilo, Hawaii, sending waves between 20 and 32 feet high crashing into the downtown area. The flooding caused widespread destruction and killed more than 150 people. The disaster led to the creation of the Pacific Tsunami Warning Center, which monitors earthquake activity and issues tsunami alerts for coastal communities.

In 1964, a massive earthquake off the coast of Alaska generated a tsunami that struck California, Oregon, and Washington. Waves between 10 and 20 feet high damaged ports and coastal towns along the West Coast. Then, on December 26, 2004, one of the deadliest natural disasters in recorded history struck the Indian Ocean. An underwater earthquake off the coast of Sumatra registered a magnitude of 9.3 — the second largest earthquake ever recorded — and triggered a series of devastating tsunamis.

The 2004 Indian Ocean tsunamis swept across thousands of miles of ocean and struck coastlines in more than a dozen countries, from Indonesia to Sri Lanka, India, Thailand, and even the coast of East Africa. The estimated death toll was nearly 230,000 people. Nearly four out of five tsunamis occur in an area of the Pacific Ocean called the Ring of Fire — a region where many of the world’s most active volcanoes and earthquake zones are located. Preparedness, early warning systems, and public education remain the best defenses against tsunami disasters.

Download the Worksheet

Full Members can download the printable PDF worksheet and answer key.

Looking for more reading comprehension worksheets? Browse all reading lessons or become a Full Member to access every printable PDF.