Earlier today at 3:00pm Tokyo time a magnitude 8.9 earthquake occurred 235 miles Northeast of Tokyo and it was the biggest earthquake in modern Japanese history.
The earthquake was from a subduction zone fault where one tectonic plate is driven with tremendous pressure underneath another tectonic plate. As a result of this massive shift in the earths crust an incredible amount of water is displaced and with today's earthquake it unleashed a 23-foot tsunami that swept boats, cars, buildings and tons of debris miles inland in Sendai Japan.
This phenomenon is called a "tsunami" (pronounced soo-NAH-mee) which is a series of ocean waves that are generated by disturbances associated primarily with earthquakes occurring below or near the ocean floor. Tsunamis can also be produced by underwater volcanic eruptions and landslides.
This phenomenon has been seen recently in Thailand in 2004 and in Chile in 2010.
Most people know little about Tsunamis and this article will cover some common myths associated with them.
1. A tsunami is a single wave. Once it has occurred you are safe.
This is false. A tsunami is a series of waves. There may be 5 to 20 waves that come during fixed periods which are typically 10 minutes to 2 hours. The first waves are typically small, and subsequent waves become larger. Therefore, if you don't get washed away by the first wave, you still need to stay away from the shoreline to escape the others.
The most devastating effect of Tsunamis is that after one wave hits and causes damage, the water recedes as the next wave approaches taking with it all of the debris associated with the first wave. Then when the next wave hits all the water and debris moves inland yet again with even more force and weight behind it causing even more damage and devastation.
2. A tsunami looks like a curling 30-foot high wave as seen in the opening of the TV show Hawaii 5-O.
This is false. While a tsunami could sometimes have this appearance, this type of wave is not a typical tsunami. Originally Tsunamis were called "tidal waves" for a good reason. They resembled the tides much more than a wave.
A good analogy to demonstrate a tsunami would be if you had a large plastic bucket full of water and you lifted up one side of the bucket. You would see that the water would be displaced and slosh out on the opposite side of the bucket very quickly. As you watch the wave come out it doesn't really have a particularly large slope, but there's a lot of it. Sometimes, a tsunami won't even break or curl like a wave when it hits the shore and as a result that makes the wave look smaller than it really is. This was seen in Thailand in 2004 if you've seen video's of that tsunami on YouTube.
Also, what makes a tsunami so destructive is not the height of the wave, but rather the large volume of water that pours out onto the beach and inland.
3. There's not much that you can do to avoid a tsunami.
This is also false. If you happen to be on the seashore and the tide suddenly goes out and you see fish flopping in the mud and sand, this typically means that a tsunami is coming. You should move to higher ground immediately. Fish are smart creatures and they never flop around when low tides happen daily. The water will often recede as much as 1000 yards from the beach before the first tsunami wave hits. However, there is no guarantee that this will always happen either.
4. If you can grab onto a solid object, you are likely to survive a tsunami.
This is most certainly false. There are many things that can happen to you when a Tsunami hits. Despite the fact that you may not have drowned or gotten washed away, you could still be struck by piece of wood, branches, rocks, vehicles, and other objects traveling in the water at 30 miles per hour.
One cubic yard of sea water weighs about 1,700 pounds. That is nearly one ton. A tsunami wave moving at 30 miles per hour has kinetic energy equivalent to the solid mass of medium sized SUV traveling at 20 miles per hour. Even a very strong person would not be able to hang on to a solid object for support with this much energy behind it.
To truly understand the incredible power behind a tsunami watch this video which shows the first tsunami wave to hit Sendai Japan. You will not believe your eyes. http://www.youtube.com/watch?v=ugqdyJQHsy4
In conclusion, people on the beach or in low coastal areas need to be aware that a tsunami could arrive within minutes after a severe earthquake and they should quickly move away from the water and to higher ground. If the surrounding area is flat, move further inland. Also, always carry a radio with you when you go to the beach and make sure that it has fresh batteries in it.
Tsunamis cannot be stopped but with some knowledge you can be better prepared to protect yourself and your family should you be caught in an area where a tsunami may strike.
If you are considering buying a home on or near the beach you will find that when you order a Property I.D. NHD report we also cover tsunamis.