Tsunamis are giant waves caused by earthquakes or volcanic eruptions that can reach heights of 30 meters and travel as fast as jets. Mudslides are fast moving landslides made of mud that destroy everything. Earthquakes are caused by movement of tectonic plates under the earth's surface and occur suddenly, mostly in the Pacific Rim. Avalanches are like mudslides but made of snow and ice, traveling at 80 mph in mountains after fresh snowfalls.