The massive earthquake that hit Japan will likely have minimal impact on the U.S., said a University of Southern Mississippi marine science professor.
Dr. Vernon Asper, whose expertise includes marine geology and geophysics, teaches courses that include an examination of tsunamis and their impact. He said the tsunami resulting from the earthquake will have dissipated significantly by the time it reaches the west coast of the U.S. mainland
A tsunami is a sequence of waves that occur following a sudden shift of the ocean floor that also cause an earthquake, and its severity is determined by the geometry of the motion of the quake, Asper said.
“A tsunmai is best visualized as a shock wave moving 500 miles an hour, the speed of a jetliner. At sea, it has a very small height and if you were on a boat you might not even notice it going by, but it has an enormous amount of energy,” he said.
“In shallow water, that energy bunches up and causes the wave to get taller, and it either breaks or rushes in over land. The damage from the one that hit Japan is pretty severe, but it could have been worse.”
Japan is in what is known as a subduction zone, where one piece of the earth’s surface is sliding under another. Today’s earthquake was centered on the action of the Pacific plate sliding under the Eurasian plate.
“This sliding motion is going on all the time, but the boundaries of the plates get stuck, accumulating tension and eventually slip, and that’s what caused this quake,” Asper said.
Japan’s history is marked by frequent earthquakes and tsunamis, but Asper said today’s event is one of the worst on record. “This was an extremely strong earthquake, nearly as strong as the one that hit Indonesia (in late 2004), and one of the strongest that has occurred in my lifetime.”
To learn more about Dr. Asper and his research, online visit http://www.usm.edu/marine/faculty/vernon_asper.php