Scientists mapping the seafloor off the coast of Alaska have identified a segment of the subduction zone they say signals the potential for a major tsunami in an area that normally would be considered benign.
© Kyodo
After-effects of Japan's tsunami.
Major tsunamis usually occur at the shallow portions of subduction zones, the areas where one of the tectonic plates that make up Earth's surface dives below another. Called crash zones, they are dangerously active and tectonic interactions can cause some of the world's biggest earthquakes and tsunamis.
The research, led by seismologist Anne Bécel of Columbia University's Lamont-Doherty Earth Observatory, shows that segments of subduction zones capable of producing tsunamis have
three characteristic structural configurations and the mapping and study of the subduction zone off the Alaska coast "suggests this part of Alaska is particularly prone to tsunami generation."
"The possibility that such features are widespread is of global significance." In addition to Alaska, she said, "waves could hit more southerly North American coasts, Hawaii and other parts of the Pacific." Bécel noted that when the energy at the point of subduction is high and suddenly is released, the resulting earthquake can make the ocean floor jump up and down like a spring. The motion then transfers to the overlying water, creating the tidal wave.
