Besides earthquakes, tsunamis can also be caused by volcanoes and landslides. Tsunamis resulting from volcanoes occur when the volcano is either near an ocean or under the surface of one. The tsunami forms when debris, lava or a pyroclastic flow from the volcano displaces the water (see Figure 3).
Underwater landslides also cause tsunamis. When a large chunk of land shifts underwater, some of the water is pushed up, and some is pulled down. This creates a ripple in the water that becomes a tsunami.
Most tsunamis go unnoticed; only those that kill lots of people gain public attention. For example, during the past 100 years, there have been more than 200 tsunamis in the Pacific Ocean alone. See Table 1 for a list of notable Tsunamis from the last 200 years.