Tsunamis

The phenomenon we call a "tsunami" is a series of traveling ocean waves of extremely long length and period, generated by disturbances associated primarily with earthquakes occurring below or near the ocean floor. Underwater volcanic eruptions and landslides can also generate tsunamis, although these sources are significantly less frequent.

As the tsunami crosses the deep ocean, its length from crest to crest may be 124 miles or more and its period 15 minutes to an hour, but its height from trough to crest may only be a few inches, even for a very destructive tsunami, it cannot be felt aboard ships in deep water. As the tsunami enters shallow water near coastlines in its path, the velocity of its waves decreases and its wave height increases.

It is in these shallow waters that tsunamis become a threat to life and property because they can crest to heights of more than 30 feet, strike with devastating force, and flood low-lying coastal areas. There are records of tsunamis reaching heights of more than 100 feet.


NOTIFICATIONS
Tsunamis may strike in a matter of minutes (following a local earthquake) or within hours, depending on how far the epicenter is from Okinawa.

Warnings and notifications will be passed promptly by one or more of the following means:

- The 18th Wing command post
- American Forces Network (AFN) television and radio announcements
- The Kadena Web page www.kadena.af.mil
- The Kadena commander's access channel
- On base siren system: a long steady tone followed by a warning message.
- Off base siren system: a long steady tone followed by a warning message.

To be safe, throughout the event of a tsunami, listen carefully to TV or radio reports. More current tsunami information can be found at the National Weather Service's Pacific Tsunami Warning Center Web site at www.prh.noaa.gov/ptwc.

Don't go back to low-lying areas until the watch or warning expires or is cancelled!


TSUNAMI SAFETY RULES
1. All earthquakes do not cause tsunamis, but many do. When you hear that an earthquake has occurred, tune into AFN radio or TV for a tsunami emergency message.

2. An earthquake in your area is a natural tsunami warning. If you are at the beach and feel violent shaking (enough to knock you off-balance) wait for it to stop, and then move quickly to higher ground. If a tsunami is generated, it will arrive in a few minutes. Do not stay in low-lying coastal areas after a strong earthquake has been felt.

3. A tsunami is not a single wave, but a series of waves. Stay out of danger areas until an "all-clear" is issued by a competent authority.

4. Approaching tsunamis are sometimes preceded by a noticeable rise or fall of coastal water. This is nature's tsunami warning and should be heeded.

5. A small tsunami at one point on the shore can be extremely large a few miles away. Don't let the modest size of one make you lose respect for all.

6. All warning to the public must be taken very seriously, even if some are for non-destructive events. The tsunami of May, 1960 killed 61 people in Hilo, Hawaii, because some thought it was just another false alarm.

7. All tsunamis, like typhoons, are potentially dangerous, though they may not damage every coastline they strike.

8. Never go down to the shore to watch for a tsunami. When you can see the wave, you are too close to escape it. Never try to surf a tsunami; most tsunamis are like a flash flood full of debris and they do not curl or break like surging waves.

9. Sooner or later, tsunamis visit every coastline in the Pacific. Warnings apply to you if you live in any Pacific coastal area.

10. During a tsunami emergency, your local police and on-base officials will try to save your life. Give them your fullest cooperation.


HOUSING AREAS IN TSUNAMIS FLOOD ZONES

On-base housing:
The following housing areas may be potentially impacted by a tsunami

· Kinser Towers: Residents should evacuate the lower 4 floors of the tower by either seeking refuge in the 5th floor or higher or going to higher ground on Camp Kinser.

· Old Lester Housing: Residents should seek refuge in their 2nd floor or relocate to New Lester Housing and wait for further instructions

Off base housing:
Off base housing residents need to review the drawings on pages 11-21 of the Emergency Action Guide to determine if their unit is in the tsunami flood plain.

Residents should determine their best course of action and prepare an evacuation plan. If you live in a two or more story unit, seek immediate refuge on the highest floor. If you have time to evacuate, go to your nearest military installation or seek the highest ground in your immediate area that is out of the tsunami flood plain.

Off base residents who live in the tsunami flood plain are responsible for providing contact information to their unit for notification and recall purposes. If your home was damaged to the extent that you need temporary shelter, then proceed to the nearest on-base shelter once the tsunami has subsided.

For guidance on appropriate shelters to evacuate to, refer to the Evacuating from Off-Base Quarters to On-Base Shelters on page 29 of the Emergency Action Guide.