By Sid Perkins
A new theoretical model that describes a tsunami’s interaction with winds may explain enigmatic observations associated with some of the high-speed ocean waves and could lead to a technique for spotting approaching tsunamis long before they hit shore.
On several occasions, people have observed dark, kilometer-wide bands on the ocean surface as tsunamis approached or passed by—a phenomenon that researchers call a tsunami shadow. In 1946, a pilot flying north of Hawaii reported a dark band on the ocean surface that outraced his aircraft. That shadow was associated with a tsunami spawned by a temblor off the coast of Alaska.