Tsunamis are waves in an ocean or large lake caused by a disturbance in the water, such as an underwater earthquake, volcano, or landslide.

To say tsunami, add the name Sue to the word mommy, but change the first m to n: sue-nommy.

In English, we don’t usually have a Ts at the beginning of words, so we make the T silent and just say the s. But it’s okay to add the T if you’d like. Touch your tongue to the top of your mouth as if about to say a T word, but say Sue instead: tsue-nommy.

Normal ocean waves are caused by wind or by tides, which are generated by the gravitational pull of the moon and the sun.

Disturbances that cause tsunamis don’t always have to come from under the water. An explosion or a meteor hitting the water could cause a tsunami. So could an avalanche that hits the water.

Tsunami waves can range in size from tiny to gigantic, depending on the power and location of the event that produces them. When large waves reach land, they often cause flooding and destruction.

You may have seen reports recently about a volcano that erupted in the South Pacific near the island nation of Tonga. On January 14, about 40 miles from the capital of Tonga, an exploding volcano not only shot tons of ash into the sky, it caused a powerful tsunami.

Because the eruption occurred so close to Tonga, the tsunami waves that hit there were 49 feet high. That’s almost as tall as a five-story building.

Tsunamis caused by the January 14 volcano struck other countries as well, including New Zealand, Japan, the Russian Far East, Chile, Peru, and even the west coast of the United States. Those waves were not as high as the ones that struck Tonga, but were still powerful enough to cause flooding and damage.

Though there have been plenty of tsunamis that were smaller than the one on January 14, there have also been some that were much larger.

In 2004, an earthquake near the west coast of Sumatra, Indonesia created tsunami waves that were 100 feet tall — the height of a nine story building! Those tsunamis killed more than 200,000 people in 14 countries, making it one of the deadliest natural disasters in recorded history.

The Atlantic Ocean has fewer and smaller tsunamis than the Pacific Ocean does, which is good news for Maine.

According to the Maine government’s website, only small tsunamis have ever hit Maine. The largest ones were in 1872 and 1926. The tsunami that hit in 1872 had waves that were only about 20 inches high. The one in 1926 was larger and hit Canada’s east coast pretty hard. The waves that hit Maine, though, were smaller, about 10 feet high, and flooded Bass Harbor on Mt. Desert Island. No one there was injured or died.

Interesting Facts

•  Tsunami is a Japanese word that means harbor wave.

•  People used to call tsunamis “tidal waves,” but have stopped using that term because tsunamis don’t have anything to do with tides, which are caused by the gravity of the sun and moon pulling on large bodies of water.

•  In 479 BC, a tsunami helped save the coastal town of Potidaea, Greece. The town was being attacked by Persians, but a giant wave hit the Persian army, spoiling the attack. The Greeks believed the wave was sent by Poseidon, who was their god of the sea and storms.