What is a tsunami?
Tsunamis are generated by a sudden, impulsive displacement of sea level. This displacement is usually associated with an earthquake but can be caused by landslides and volcanic activity.

These waves can occur within minutes or hours after an earthquake depending on where the earthquake occurred, and may occur as multiple waves.

The photo to the right is from Kodiak, Alaska, after the 1964 Great Alaska Earthquake and tsunami.
What does the word "tsunami" mean?
Kodiak Island, Alaska, 1964. Photo courtesy of NOAA.