Tsunami

(May 1, 2011) There’s been a lot in the news about tsunamis since the incredibly destructive tsunami that struck Japan on March 11, as well as less destructive tsunamis that hit Hawaii, California and other places. Tsunami is a Japanese word coined to describe wave that initially had nothing to do with destruction. The word means “harbor wave” and was coined to describe waves fisherman and other people along Japan’s coast observed. In protected harbors where the surface of the water was mirror smooth, waves would be generated when fishing boats came into the harbor after a day’s fishing at sea. As a wave moved across the surface toward shallow water along the shoreline people noted that the wave slowed and increased in amplitude and they called them tsunami – harbor waves. Some in the west called waves produced by undersea earthquakes or volcanoes “tidal waves”, however they have nothing to do with the tides, therefore, that term is no longer used.  Today the term tsunami is always used with waves that have the potential to be very destructive as was the case recently in Japan. Some coastal cities north of Sendai had seawalls ten meters high and water about two meters deep, or more, breached the seawall which means the tsunami was at least 40 feet high. or the ground near and beneath the seawall dropped about six feet which some say was the case.