What causes tsunamis to travel across oceans?

Tsunamis travel across oceans because they involve the movement of the entire water column, not just the surface. Triggered by underwater earthquakes, volcanic eruptions, or landslides, tsunamis generate long wavelengths and high energy. These characteristics allow them to travel at speeds of up to 800 km/h in deep water. As they approach shallow coastal areas, their energy compresses, causing waves to grow taller and more destructive.