6.9 quake in Alaska poses no Tsunami threat
A 6.9-magnitude earthquake Sunday night in the central Aleutian Islands in Alaska is definitely not strong enough to send a tsunami to the Bay Area, a tsunami program manager with the National Tsunami Warning Center said.
Tsunami program manager Cindi Preller said the threshold for the occurrence of a tsunami is a 7.0-magnitude earthquake, which might be enough to generate a tsunami near the quake's origin.
A 6.9-magnitude earthquake does not have enough energy to send waves all the way to California, Preller said.
A 9.0-magnitude quake would be able to send waves all the way across the ocean, she said. The tsunami that struck Sumatra, Indonesia, in December 2004 was from a 9.1-magnitude earthquake, according to the National Oceanic and Atmospheric Administration.
Preller said each one-tenth increase in magnitude represents 1,000 times more energy and 32 times more ground motion. The earthquake in Alaska on Sunday was located 60 miles southwest of Nikolski and originated at 9:49 p.m.