John,

Thanks for posting a term I've not heard before and a reason to understand what it means, which is further explained below....Petra

June 15, 2005
M7.2 Earthquake off Northern California Coast, 90 Miles WSW of Eureka
Filed under: Felt Earthquakes, Significant Events, Large Events — duty @ 10:31 am
At 7:50PM local time (PDT) last night (6/14/05), there was a M7.2 earthquake located 91 miles (147 km) WSW of Eureka, CA, off the coast of northern California. Although out of the SCSN network, this event was felt in portions of Southern California, and therefore will be included in the commentary. This earthquake was felt widely throughout OR, WA, and CA, and felt as far north as Seattle, WA, as far south as Los Angeles, CA, and as far east as Susanville, CA. If you felt this quake, and would like to report it, or to view the CIIM map of felt reports, click here.

The event focal mechanism shows evidence of horizontal strike slip motion, which is generally not the type of motion associated with tsunamigenesis (i.e. events that generate a tsunami). Tsunamigenesis usually involves some type of vertical ground motion of the sea floor, and generally occurs when significant uplift has occurred on the ocean floor, thereby displacing the water above, and in turn creating a tsunami.

This quake triggered the West Coast Tsunami Warning System to issue a tsunami watch for the west coast of the US, from British Columbia, Canada south to the California/Mexico border. A destructive tsunami was NOT generated, and therefore the tsunami watch was cancelled and an all-clear was issued soon after the original bulletin issued.