Floods, earthquakes, tornadoes, volcanic eruptions, hurricanes, tsunamis and landslides are all natural disasters. They can be devastating financially to an area. For example, earthquakes can cause buildings to collapse, fires, and can trigger other events such as tsunamis and volcanic eruptions. Volcanic eruptions can release ash which makes roofs collapse under its weight. Pyroclastic flows of hot volcanic ash rush down the slopes and can devastate structures in its path, like the Pompeii disaster in Italy. A lahar is a mudflow due to a volcano and a village can become buried under this flow. Floods occur when water is flowing and overflows levees, or escapes its usual boundaries. After hurricane Katrina in New Orleans in 2005, many homes were washed away with the flood waters. Hurricanes can be destructive when certain buildings cannot withstand such powerful winds that accompany them. Tornadoes are violent, rotating columns of air associated with thunderstorms. Due to the wind speeds from 110 mph and up to 300 mph, they can destroy buildings and even uplift and carry objects in their paths.