head of the wave
By Stephen Ornes / February 13, 2013
Bump a glass and any water inside might slop over the side. Splash in the bathtub
and waves slosh. Toss a rock into a pond and ripples move outward in expanding
rings. In each case, the water moves in waves. Those waves carry energy.And the
more energy that gets added to a watery environment, the more powerf ul the
waves may become.
Now imagine an undersea earthquake and the tremendous amount of energy it
can transf er to the ocean. That is because the movement of the Earth's crust can
shif t
huge
volumes
of
water,
unleashing a parade of great and powerf ul waves. The water races away at speeds up to 800 kilometers
(500 miles) per hour, or as f ast as a jet plane.
Eventually those waves reach shallow water. They slow down and swell, sometimes as high as a 10-story
building. When the waves eventually crash onto land, they can swamp hundreds of kilometers (miles) of
shoreline. They may snap trees like twigs, collapse of f ice buildings and sweep away cars.Among nature’s
most powerf ul f orces of destruction, these waves are called tsunamis (tzu NAAM eez). The Japanese term
means “harbor wave.”
Tsunamis strike coastal regions about 10 times every year. The f irst of this year occurred on February 6,
af ter an earthquake shook the seaf loor of f the Solomon Islands. The quake unleashed a tsunami that
killed at least f ive people in the southwestern Pacif ic island nation.
Two f ar