Waves, of course, have two parts: the peak and the trough.
With a tsunami, the trough (the low point of a wave) is the first part to arrive, causing the sea to recede far from the shore — a telltale sign of an impending tsunami.
Tsunamis, such as the one generated by the magnitude 8.9-magnitude earthquake that struck Japan today (March 11), are often generated by massive ruptures beneath the Earth’s surface underneath the ocean floor.
When the earthquake ruptures along a fault line, the surface around that fault is pushed up and then dropped back down.
This story might not have captured my attention if it hadn’t been for a fortuitous coincidence.
Essays On Tsunami In Japan
The day before, an engineering colleague, Eiichi Taniguchi, had told me that researchers at Tohoku University in Sendai, Japan, had found sediments indicating that a huge tsunami had hit Miyatojima about 1,000 years ago.Next, the peak of the wave hits the shore — a process called runup.Except for the largest tsunamis, such as the 2004 Indian Ocean event, most tsunamis do not result in giant breaking waves (like normal surf waves at the beach that curl over as they approach shore).FOR THE RECORD: Tsunami: In a March 11 Op-Ed about a 1,000-year-old story that saved lives after the Tohoku earthquake, the last name of a Japanese engineer was misspelled. — In a refugee center on the beautiful island of Miyatojima, at the entrance to Matsushima Bay, I stumbled on a story that, by its reach back in time, taught me something unexpected: Collective memory, as much as science and engineering, may save your life.After a long day of field work, my colleagues and I were chatting with a community leader, Koutaro Ogata, from a fishing village called Murohama.I have to admit that I have not been able to keep this story of survival out of my mind. Reaching out from the distant past, long-gone ancestors — and a deeply embedded story — saved their children.José Holguín-Veras is an engineering professor at Rensselaer Polytechnic Institute in New York and a member of the National Academy of Sciences’ Disaster Research Roundtable. Tragically, not everyone made the right choice; I was told of at least one person who died.Later, I saw the shrine — a simple clearing by the side of a hillside road, with stone tablets and roughly made figures — and I heard the old story and the new one again: A community remembered what it had been told and did the right thing. A message sent into the future 1,000 years ago did.Tsunamis at sea and shore Tsunamis at sea are not the monster waves that might be imagined — they are at most a few meters high and are spread over tens to hundreds of kilometers.[Album: Monster Waves]As the tsunami approaches a shoreline, where the rise of the continental slope means water levels are shallower, the wave begins to narrow and become higher.