Surviving a Tsunami

A tsunami is not a tidal wave. They are in no way related to the gravitational forces that influence the tides. Instead, tsunamis are a series of long waves traveling through the ocean. These waves are formed by geological disturbances such as earthquakes, underwater volcanic eruptions, and landslides. They can form hundreds or even thousands of miles away and the waves have been known to range from 50 to 100 feet in height.

When near the ocean, be aware of the warning signs of an approaching tsunami include a significant and unusual rise or fall in the sea level, ground shaking, or a loud, sustained roar.

If you are on a boat in a small harbor and you have sufficient warning of an approaching tsunami, move the boat as quickly as possible. The ideal would be to dock and head for high ground. The next best option is to take the boat far into open water so that you are away from the shore. This will reduce the chance that the boat will be thrown into the dock or the land. In addition, the deeper water could mean that the tsunami's waves will pass by you beneath the water. Tsunami waves cause damage when they move from deeper to more shallow waters as they back up against one another as the water becomes shallower.

If you are on land, seek higher ground immediately. Tsunamis can move faster than a person can run. At the very least, get away from the coastline as quickly as possible.

If you are in a high-rise hotel or apartment building on the coastline and you do not have enough time to get to higher ground away from the shore, move to a high floor of the building. Similarly, the upper floors of a high-rise building can provide safe refuge.

Be aware that the first tsunami wave may not be the largest in the series of waves so stay put after the first wave hits until you are assured of your safety. Also be aware that tsunamis can travel up rivers and streams that are connected to the ocean. Flooding from a tsunami can extend inland 1,000 feet or more, covering large expanses of land with water and debris.

References:
The Worst Case Scenario Survival Handbook – Travel by Joshua Piven and David Borgenicht