Environmental Process/Catastrophic Events Forest fire - an uncontrolled fire in a wooded area Volcano - an opening in the earth's crust through which molten lava, ash, and gases are ejected Earthquake - A sudden movement of the Earth's lithosphere (its crust and upper mantle). Earthquakes are caused by the release of built-up stress within rocks along geologic faults or by the movement of magma in volcanic areas. They are usually followed by aftershocks. Tsunami - a large destructive ocean wave caused by an underwater earthquake or another movement of the Earth's surface Hurricane - a severe tropical storm with torrential rain and extremely strong winds tornado - A rotating column of air ranging in width from a few yards to more than a mile and whirling at destructively high speeds, usually accompanied by a funnel-shaped downward extension of a cumulonimbus cloud. Landslide - The downward sliding of a relatively dry mass of earth and rock. Glaciers - are large masses of snow, recrystallized ice and rock debris that accumulate in great quantities and begin to flow outwards and downwards under the pressure of their own weight. Currents - cohesive streams of seawater that circulate through the oceans. Ocean currents can be generated by wind, density differences in water masses caused by temperature and salinity variations, gravity, and events such as earthquakes.