TSUNAMI

What is Tsunami?

Tsunamis (pronounced soo-ná-mees), also known as seismic sea waves (mistakenly called “tidal waves”), are a series of enormous waves created by an underwater disturbance such as an earthquake, landslide, volcanic eruption, or meteorite. A tsunami can move hundreds of miles per hour in the open ocean and smash into land with waves as high as 100 feet or more.

From the area where the tsunami originates, waves travel outward in all directions. Once the wave approaches the shore, it builds in height. The topography of the coastline and the ocean floor will influence the size of the wave. There may be more than one wave and the succeeding one may be larger than the one before. That is why a small tsunami at one beach can be a giant wave a few miles away.

All tsunamis are potentially dangerous, even though they may not damage every coastline they strike. A tsunami can strike anywhere along most of the U.S. coastline. The most destructive tsunamis have occurred along the coasts of California, Oregon, Washington, Alaska and Hawaii.

Earthquake-induced movement of the ocean floor most often generates tsunamis. If a major earthquake or landslide occurs close to shore, the first wave in a series could reach the beach in a few minutes, even before a warning is issued. Areas are at greater risk if they are less than 25 feet above sea level and within a mile of the shoreline. Drowning is the most common cause of death associated with a tsunami. Tsunami waves and the receding water are very destructive to structures in the run-up zone. Other hazards include flooding, contamination of drinking water, and fires from gas lines or ruptured tanks.

What Causes Tsunami?

1. Earthquakes

Most tsunami are caused by the large earthquakes on the sea floor when stabs of rock move past each other suddenly, causin the overlying water to move. The resulting waves move away from the source of the earthquake event,

2. Landslides

Underwater landslides can cause tsunami as can terrestrial land which slumps into the ocean,

3. Volcanic eruptions

Less common are tsunami initiated by volcanic eruptions. These occur in several ways:

• destructive collapse of coastal, island and underwater volcanoes which result in massive landslides.
• pyroclastic flows, which are dense mixtures of hot bloacks, pumice, ash and gas, plunging down volcanic slopes into the ocean and pushing water outwards.
• a caldera volcano collapsing after an eruption causing overlying water to drop suddenly.

Effects of Tsunami

1. Destruction

The amount of the energy and water contained in a huge tsunami can cause extreme destruction when it strikes land. The initial wave of a huge tsunami is extremely tall; however, most damage is not sustained by this wave. Most of the damage is caused by the huge mass of water behind the initial water front, as the height  of the sea keeps rising fast and floods powerfully into a coastal area. it is the power behind the waves, the endless rushing water that causes devastation and loss of life.

Destruction is caused by two mechanisms: the smashing force of a wal of the water travellng at high speed, and the destructive power of a large volume of water draining off the land and carrying all with it, even if the wave did not look large.

2. Death

One of the biggest and worst effects of a tsunami is the cost of human life because unfortunately escaping a tsunami is nearly impossible. Hunderds and thousands of people are killed by tsunamis. Siince 1850 alone, tsunamis have been reponsible for the loss of more than 430,000 lives. There is very littlr warning before a tsunamis hits land. As the water rushes towards land, it leaves very little time to map an escape plan.

3. Disease

Tsunami waves ad the receding water are very destructive to structures in a run-up zone. The areas close to the coast are flooded with sea water, damaging the infrastuctrue such as sewage and fresh water supplies for drinking.

4. Environmental impacts

Tsunami not only destroy human life, but have a devastating effect on insects, animals, plants, and natural resources. A tsunami change the landscape. It uproots trees and plants and destroys animals habitats such as nesting sites for birds. Land animals are killed by drowning and sea animals are killed by pollution if dangerous chemical s are washed away into the sea, thus poisoning the marine life.

5. Cost

Massive costs hit communities and nations when a tsunami happens. Victims and surviviors of the tsunami need immediate help from rescue teams. Government around the world may help with the cost of bringing aid to devastated areas. National institutions, the United Nations, other international organizations, community groups or NGOs, and a variety of other and services.

Picture: Tsunami Japan 2011