A Tsunami or killer wave is a lot of waves that can reach over 100 ft high. Tsunamis cause lots of destruction when it slams onto shore. Some Tsunamis can reach speeds of up to 5000 miles per hour which means it can cross the entire ocean in less than a day. So far, the smallest Tsunami was 30 feet high. Washington, Oregon, Hawaii, Alaska and California are the places with the highest risk of a tsunami hitting.
Tsunamis can be caused or created by large earthquakes, which can cause Underwater landslides, because the water is trying to get stable. Tsunamis can also be caused by underwater volcanoes, if it has enough force. So, one sign that there might be a tsunami is if there is a strong earthquake. Also, you should watch the news and keep on a radio, so you know if there were any strong earthquakes near the place you were going to go to.