A larger Mag 6.4 earthquake tripped offshore of Seattle WA last night. It is the latest in a small swarm of Mag 4, Mag 5, and now Mag 6 earthquakes that began two days in the Cascadia Fault Zone that runs from British Columbia south to Northern California. The Cascadia Fault is regularly hit with Mag 8 (average interval 350 years) and occainsional Mag 9 (interval about 580 years) earthquakes. The last very large killed thousands of native Indians up and down the Washington and Oregon coastline in January 1700, and hundreds more in Japan from its tsunami waves.