You Say Tsunami

As I write, the news is saturated with stories of the earthquake and tsunami that have devastated parts of Asia and Africa.  The death toll is currently at 117,000 lives lost, a disproportionate number of them children, and still rising.  I am saddened by the suffering, but fascinated nonetheless by the power of the sea.  I find myself examining pictures of the devastation and endlessly replaying the few videos I’ve found of the actual event, trying to comprehend and envision this destructive force.

 

Prior to this event, I imagined tsunami as very rare and almost mythical phenomena.  I knew that they traveled through deep water at extreme speeds and almost unnoticed, only to be forced up to the surface by a rising coastline.  However, I had always imagined them as sinister, curling, breakers towering as high as a building and rolling ashore at high speed to crush the shoreline with their weight.  While those do exist, it seems not to have been the case here.  All the video that I have been able to see, which admittedly was shot from cheap cameras by terrified tourists, shows something quite different.

 

Rather than the high frequency and short wavelength that I would have expected, yielding a veritable rushing wall of water, these waves seemed to have a very low frequency and long wavelength.  They did not crash ashore like some beast from the North Shore of Oahu – they hardly looked surfable at all.  Perhaps this is how the came to be called “tidal” waves, because they come slowly and inexorably like the tide?

 

They were not huge waves, but they weren’t small either, and they just kept coming.  I’ve seen videos of people standing on the beach or the seawall watching the abnormal waves.  They are still standing there staring as a wave strikes the beach and keeps coming.  There is some minor drama as the wave strikes the seawall with an explosion of spray, but it scales the wall and keeps coming.  It starts off only inches deep as it seeks the low points of the terrain.  But it keeps coming and soon it is a torrent many feet deep as it sweeps up anything in its path.  It looks very much like a river that has jumped its banks.  Except that it isn’t a river, it is a wave, and waves recede.  And so this torrent eventually slows, stops, and then retreats back to the sea with taking people and debris with it.

 

I wonder what it would have been like to be in a sailboat near the coast when this happened.  I have come across a couple of first hand accounts by people who were just offshore when the waves arrived.  One, a fisherman, described the water swirling around his boat and the water level dropping to such a degree that he could see the bottom (doesn’t really give any indication of how much it dropped).  He looked toward shore and saw a “wall of water” approaching his village.  He lost his entire family.  The second story was of a pair of American divers off of Phuket who were underwater when the wave passed.  They describe being pulled down toward the bottom, no doubt the trough of the wave and the same phenomenon the fisherman noticed.  They divers surfaced, but did not see anything wrong until they neared shore and saw the bodies in the water.

 

I contrast this with a story I read a few weeks ago about Lituya Bay in Alaska.  Only July 9, 1958 at 2217, an 8.3-magnitude earthquake dislodged a 40 million cubic yard piece of mountain that then fell into Gilbert Inlet at the head of the bay.  The disturbance of the shifting plates and the falling rock combined to generate a massive tsunami that completely denuded the bedrock shore of the bay up to 1,720 feet above sea level.  There were three boats in the bay that night.  Eyewitness accounts say the tsunami crested over the 320-foot summit of Cenotaph Island in the middle of the bay.  Amazingly, one of the three boats remained in the bay and survived.  The other two boats were swept over the spruce covered spit that protected the entrance of the bay and sank in the Gulf of Alaska.  The crew of one of those boats survived.  This wave was preceded by similar waves in Lituya Bay in 1853, 1874, 1899, and 1936 making such an awesome event eerily common.  The U.S. Parks Service no longer keeps personnel at the bay and has considered banning visitors there.