The USGS (and no doubt millions of fish) has detected a 7.0-magnitude earthquake off the coast of California. People as far away as San Diego and Hawaii have gotten tsunami warnings. So far no tsunamis have been reported; we'll see when the first possible wave reaches San Francisco in an hour.
More info when available.
Update, 14:12 CST: NOAA cancelled the tsunami warning for the US and Canadian West Coast about 15 minutes ago.