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Tsunami

Tsunami is a Japanese word  that means "harbor wave".

Tsunami is a series of large waves of extremely long wavelength and period usually generated by a violent, impulsive undersea disturbance or activity near the coast or in the ocean.

When there is a sudden displacement of water  or if there is an earthquake that caused the  sea floor to be raised or dropped suddenly, big tsunami waves can be formed.  Tsunamis can be formed from the force or impact created by earthquakes, landslides, volcanic eruptions, explosions, as well as  the impact of cosmic bodies like meteorites. Tsunamis can attack coastlines causing vast destruction of properties and loss of lives.

Earthquake Generated Tsunami

Tectonic earthquakes affect the sea floor. When earthquake occurs beneath the sea, changes happen.  Large areas of the sea floor may elevate or subside.  Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the overlying water.    That is how tsunamis are formed.   

As tsunamis rush onshore, they begin to lose energy. Despite these losses, tsunamis still reach the coast with such great amount of strength to cause tremendous devastation. Tsunamis have great erosional potential, stripping beaches of sand that may have taken years to accumulate and undermining trees and other coastal vegetation. They are capable of  flooding hundreds of meters inland.  Tsunamis may reach a maximum vertical height onshore above sea level, often called a run up height, of 10, 20, and even 30 meters.

The video above shows how fast tsunamis attack. It is such a frightening scenario.  Indeed, it is difficult to prepare for such a disaster.  Thinking smart can save your life but then we can never really say for sure what really works. 

Tsunami Facts

• Tsunamis that strike coastal location in the Pacific Ocean Basin are most always caused by earthquakes. These earthquakes might occur far away or near where you live.
• Some tsunamis can be very large. In coastal areas their height can be as great as 30 feet or more (100 feet in extreme cases), and they can move inland several hundred feet.
• All low lying coastal areas can be struck by tsunamis.
• A tsunami consists of a series of waves. Often the first wave may not be the largest. The danger from a tsunami can last for several hours after the arrival of the first wave.
• Tsunamis can move faster than a person can run.
• Sometimes a tsunami causes the water near shore to recede, exposing the ocean floor. The force of some tsunamis is enormous. Large rocks weighing several tons along with boats and other debris can be moved inland hundreds of feet by the tsunami wave activity. Homes and other buildings are destroyed. All this material and water move with great force and can kill or injure people.

Pacific Tsunami Warning System

Sea-level or tidal  information is provided by NOAA's National Ocean Service, PTWC, ATWC, university monitoring networks and the other participating nations of the PTWS.   The International Tsunami Information Center, part of the Intergovernmental Oceanographic Commission, monitors and evaluates the performance and effectiveness of the Pacific Tsunami Warning System. This effort encourages the most effective data collection, data analysis, tsunami impact assessment and warning dissemination to all TWS participants.  Tsunami watches, warning, and information bulletins are disseminated to appropriate emergency officials and the general public by a variety of communication methods.

Be aware of tsunami facts. This knowledge could save your life! Share this knowledge with your relatives and friends. It could save their lives!

• If you are at home and hear there is a tsunami warning, you should make sure you entire family is aware of the warning. Evacuate if you are advised to do so. Follow instructions of authorities.
  
• If you are at the beach or near the ocean and you feel the earth shake, move immediately to higher ground. DO NOT wait for a tsunami warning to be announced. There may not be time for that.
  
• If there is a tsunami, stay away from the beach and ocean as well as rivers and streams that lead to the ocean.
  
• Tsunamis generated in distant locations will generally give people enough time to move to higher ground. For locally generated tsunamis, where you might feel the ground shake, you may only have a few minutes to move to higher ground.
• High, multi-story, reinforced concrete hotels are located in many low-lying coastal areas. The upper floors of these hotels can provide a safe place to find refuge should there be a tsunami warning and you cannot move quickly inland to higher ground. Homes and small buildings located in low lying coastal areas are not designed to withstand tsunami impacts. Do not stay in these structures should there be a tsunami warning.
• Offshore reefs and shallow areas may help break the force of tsunami waves, but large and dangerous waves can still be threat to coastal residents in these areas. Staying away from all low-lying coastal areas is the safest advice when there is a tsunami warning.
• If you are on a ship or boat do not return to port if you are at sea when a tsunami warning has been issued. Tsunamis can cause rapid changes in water level and unpredictable dangerous currents in harbors and ports.