What is a Tsunami
By Tom Clarke
A Tsunami (soo-NAH-mee) is not a single wave, rather a series of oceanic waves initiated by an earthquake, landslide or volcano. A rapid rising of the tide with underwater turbulence. A tsunami can be triggered by a giant meteor impact in the ocean. These waves can be 20 mins to hours apart. The waves can travel as fast as a commercial jet/plane. The top of the wave moves much faster than the bottom causing the sea level to rise. Reefs, canals, bays and lower level of water holding areas will slow down the waves and energy of the Tsunami. The sea can rise from a few inches to multiple feet. Usually no more than 10 feet. But some historical events show waves to rise up to 100′.
The NOAA, Federal Emergency Management Systems and US western coastline started the TWS. Using recorders on the see floor to transmit pressure changes in overhead water. This data is transmitted then to the buoys and up to satellites then to the warning centers. Tsunami Warning Systems is compiled from 26 countries (members), which monitor seismological and tidal stations covering the entire Pacific region. Looking for earthquakes, which have the magnitude and are positioned to initiate a Tsunami.
Basic Tsunami terms, which authorities use when speaking about Tsunamis.
TWS Tsunami Warning System
An earthquake has occurred somewhere, which may generate a tsunami. In general, an advisory indicates that an area is either outside the current warning or watch area or that the tsunami is not a threat to that area.
A tsunami was, or may have been generated, which could be dangerous; all persons living in or near the area that has been warned are strongly advised to evacuate immediately.
A tsunami was or may have been generated, but is at least two hours travel time to the area in Watch status.
- Have food rations for at least three (72 hours) days.
- Sufficiant water stored for at least three (72 hours) days. Additional should have a portable water filtration devise.
- Medications and a firstaid survival kit. *Check this quarterly for expiration dated items.
What to do before and During a Tsunami
The following are guidelines for what you should do if a Tsunami is likely in your area:
- Listen to radio and television for information on current alerts and status. If there is or has been an earthquake or if a tsunami warning has been issued or if you live on or near the coast, make decisions as information comes in and do not discount your own instincts.
- Get supplies for at least three days if you did not already have these prepared.
- Gather your family and quickly move inland and to the highest ground you can get to. Stay there until it is declared safe to go back.
- If in a high rise or hotel. move to the higher floors if cannot get out of the area
- Stay out of the water
- Stay away from coastal areas and the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it.
- NOTE: – If you are at the beach and you see the water moving unusually away from the shoreline—RUN to high ground. This is a warning from Mother Nature that a tsunami is about to strike.
For boat owners and sailors
- Take your boat out to sea if there is time and premission is granted.
- Dangerous currents in harbors, ports and rivers with conections to the ocean.
- If out at sea, vessels and large boats should not return to port if a Tsunami warning has been issued.
What to do after a Tsunami
- Do not go to lower ground until the all clear has been given.
- Save yourself and your family—not possessions or material things
- Be very careful of debris in and on the water
- Stay away from flooded and damaged areas until authorities say it is safe to return.
- If you hear or feel a strong noise like a freight train move rapidly to higher ground.
- Earthquakes are a strong warning sign.
- The first waves are usually not the biggest.
- Tsunamis weaken with time.
- Commonly starts from earthquakes with a change in the ocean floor.
- Can travel thousands of miles away.
- Most Tsunami only rise 10′
- Generally Tsunamis are not generated from earthquakes of a 6 or less magnitude.
- DO NOT stay on you boat in the harbor.
- Rapid changes in the water levels and currents can be expected. Not only in the ocean, but streams, rivers, bays, harbors or any water source connected to the ocean.
- The surge can move out as fast as in came ashore.
- The surge is not constant across the coastal line. It can be much stronger just down the coastline.