Tsunamis are large ocean waves set in motion by unstable sea floor activity. Undersea earthquakes, landslides or volcanic activity are the events capable of destabilizing the sea floor's surface. Undersea earthquakes where the earth's plates shift are the most common cause of tsunamis. When set in motion, waves are generated from the sea floor on up to the surface of the water. These waves then grow in height and intensity as they travel towards costal lines. By the time they reach land, waves can stand as high as 100 miles tall. The force of these waves is substantial, and can result in significant damage. The 2004 event that took place in the Indian Ocean is one such example of the massive force these waves can generate. According to a United States Geological Survey, the waves which reached the shore in the Indian Ocean tsunami event released as much energy as 23,000 atomic bombs. The resulting damage to the ecosystem can be catastrophic and far-reaching.
Upon impact, tsunami waves are capable of dislodging any land formations, foliage and nearby bodies of water. As the power behind these waves pushes them inward, ocean waters can reach several miles inland. As a result, fresh water lakes become contaminated with salt water, while salt sedimentation is embedded in the lakes' soil. Runoff from inland areas can leave trash and silt to rest in lake waters. Resulting damage from tsunami waves dislodges existing flora and fauna, leaving leftover sedimentation to smother undersea corals and grasses. Costal forestation undergoes significant damage, and can be totally wiped out under severe conditions. As waters begin to recede, non-biodegradable debris is swept through inland areas and dragged into the ocean waters. Contaminated soil in which crops and vegetation are grown kills off bacteria populations needed to maintain the soil's ecosystem.
Ecosystems that lie along coastal lines include mangrove forests, sea grasses, coral reefs and wetlands. Each of these ecosystems is dependent on the others for nutrient supplies. The elimination of one or more systems may permanently alter the overall environmental status. Coral reef structures destroyed in the wake of an event also kill off any existing fish populations. This absence can lead to a significant break in an ecosystem's food chain, and ultimately work to eliminate species that are dependent on that food supply. Soil exposed to salty sedimentation loses its fertility, and so becomes sterile. As result, soil located in agricultural areas must be re-cultivated, which is a long, costly process. Tsunami waves can also cause the erosion of costal terrains which will continue to erode for years afterward. As new terrains grow in, the surrounding ecosystems may never be the same due to the loss of bacterium, plant and marine species.