This document discusses different natural disasters and focuses on tsunamis. It states that tsunamis can be caused by volcanoes, earthquakes, or landslides underwater. For volcanoes, an eruption under the sea can break pieces of the volcano that fall into the water and cause pressure increases that result in huge waves. Earthquakes beneath the ocean floor can also displace water and slowly generate enormous tsunami waves. Landslides into bodies of water function similarly by adding pressure from displaced material, forcing water upwards and creating gigantic waves.