Know the Signs
Wayne Hodges and the group of boaters in Pago Pago Harbor never received an “official” warning of the impending tsunami. But nature provided clues. Knowing how to read the signs, and acting on them, can be the difference between life and death.
The first clue of a tsunami threat was the earthquake. Although Hodges did not immediately recognize the “thrumming” to be from an earthquake (he initially thought it might be from the propellers of a freighter), it lasted long enough for him to ponder it and walk topside to investigate. When he saw the lampposts and telephone poles “swaying like blades of grass in a gentle breeze,” he realized it was an earthquake. But the duration of the quake should have told him that there was a real risk of a tsunami. Hodges estimated that the shaking lasted three minutes. Other boaters in the group described it as “an earthquake which seemed to have no end.” Any time you feel a coastal earthquake you should be concerned, but if it lasts more than 30 seconds, you should launch into automatic tsunami alert.
Being on tsunami alert doesn’t mean keeping an eye out for a big wave. If you’re in the harbor or on low-lying land, you should leave. Now. Train yourself to react without hesitation. You have two choices. One is to leave your boat at the dock and head for higher ground. Just going farther inland is not the answer though, unless you are gaining altitude. The tsunamis that hit Japan in March 2011 reached as high as 133 feet and inundated low-lying areas as far as six miles inland. You want elevation.
Your other option is to take the boat out to deep water. This is risky, however, especially if you do not know how close the quake’s epicenter is. The closer the epicenter, the less amount of time you have before a tsunami arrives. It could be mere minutes. In this case it is prudent to have pre-studied local charts to know water depths outside the harbor. According to the International Tsunami Information Center you should seek a depth of 1,200 feet. The state of Washington’s Boater Education Course says 600 feet with a preference of 1,200. It is when a tsunami hits shallow water that it builds in height. In deep water it passes as a mere ripple and can often go by unnoticed.
Another clue of nature is receding water, which often precedes the arrival of a tsunami. In the devastating 2004 Sumatra quake and tsunamis, many people saw the waters recede but did not know what it meant. Eyewitness reports testify that many victims leisurely walked out onto the exposed seafloor looking for sea life and trinkets. Children played in leftover pools of water. When the tsunami arrived they did not have time to escape. The time span between receding waters and the arrival of a tsunami can vary from minutes, as in Pago Pago Harbor, to nearly an hour. Also realize that tsunamis come in a series of waves and the first one is usually not the worst.
Earthquakes and tsunamis release unbelievable amounts of energy. Some additional natural signs that a tsunami may be imminent are odd sounds, weird vibrations and unusual water behavior. Hodges heard a thrumming. Others reported hearing a deep drone like that of helicopters in flight. Some have heard booms. Sometimes before a tsunami hits, the water gets frothy with bubbles and exhibits strange conflicting currents wherein moored vessels bob or sway violently. All of these are telltale signs that should not go unheeded.
Unlike hurricanes and volcanic eruptions, which can generally be predicted early on, no one knows when the next tsunami will come. But come it will. At this very moment, somewhere along the earth’s tectonic plates, the hammer is cocked and the trigger is being squeezed. And you may be in the cross hairs. So it’s prudent to become tsunami savvy, make sure you’re set up to receive alerts and have a game plan you can launch at a moment’s notice. Because that may be all the notice you get.