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When people think of a Tsunami, what is the first thing that comes to mind? One Big Giant Wave, right? But, what is a Tsunami really?
I have been curious about this for a while and i finally found the inspiration to go looking for it. Simply put, a Tsunami is ocean waves generated by a sudden change of the ocean water level. Most commonly caused by earthquakes, but Tsunamis can also be caused by landslides, volcanic eruptions, and comet/meteorite impacts in the ocean. It is like a fast rising flood or wall of water that strikes with devastating force, that comes in a series that may continue for hours.
As a tsunami crosses the deep ocean, it could only be a few feet or less in height and cannot be seen nor can they be felt by ships. As a tsunami approaches shoreline the wave height increases and the currents intensify, creating life threatening and property damage waves. Sometimes just before the tsunami strikes, coastal waters are pulled back into the ocean, more shoreline may be exposed than even at the lowest tide.
A Tsunami wave can travel up to nearly 600 miles per hour unnoticed in deep water, that is the speed of a commercial jet plane. It is possible for it to move from one side of the Pacific Ocean to the other is less than 24 hours. As it travels to shallower coastal water the speed slows and the wave height begins to increase. Currents associated with tsunamis may reach up to 35m.p.h.
The warning signs of a Tsunami can include a strong (difficulty standing) earthquake, felt in coastal areas; a sudden unexpected rise or fall of the ocean tide; and a loud, roaring sound (similar to a train or plane) coming from the ocean
The size and impact of Tsunami waves can be determined by offshore and coastal features like reefs, bays, river entrances, undersea features and the slop of the beach. As a tsunami reaches the coast and moves inland, the water level can rise many feet. Only in extreme cases has the water rose to more than 50 feet and 100 feet at the earthquake's epicenter. The first wave is usually not the largest, one beach or coastal community may see no damage while just a few miles down shore can see more destruction. Flooding can extend inland by 1000 feet or more with debris.
How a Tsunami Works?
(this is for the most common cause, earthquake)
- An underwater earthquake occurs when plate shifts abruptly and pushes water upward with tremendous force
- Low and fast waves are generated in all directions across the ocean, some speeding as fast as 600m.p.h
- As waves enter shallower water, they are compressed, their speed slows, and they build height.
- The wave height increases and associated currents intensify becoming a threat to life and property.
The Facts
- Not every earthquake will generate a tsunami
- Tsunamis that strike coastal location in the Pacific Ocean Basin are most always caused by earthquakes.
- Tsunamis may be originate from a distant location and may not be preceded with a local earthquake
- Tsunamis can reach the coast within minutes of an earthquake's
- Some tsunamis can be very large and 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.
- Tsunamis can occur at any time, day or night.
- Tsunamis can travel up rivers and streams that lead to the ocean.
- A small tsunami at one beach may be a giant tsunami a few miles away.
All the information I have found can be found at NOAA and Storm ready
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