Scientists say a fault-line running across Alaska could cause tsunamis of the same magnitude as the Japanese disaster of March last year. Attention has turned to the Alaskan-Aleutian subduction zone, a region where one of the earth's tectonic plate, carrying the Pacific Ocean, drops beneath the North American plate. A particular section of the fault near the Semidi Islands has not ruptured since at least 1788, and measurements on this area - which lies four to five kilometres under water - reveal the pressure is accumulating rapidly. If the Pacific Ocean plate slips, as happened in the geographically-similar Tohoku subduction...