Coastal Block Motions
Posted by Don In Hollister on January 31, 2002 at 02:02:15:

Hi All. I found something I’m not sure I really wanted to find. What I found tells me the West Coast is going in different directions at the same time, while at the same time there are parts that aren’t going anywhere. Then just kind of sit there and rotate. Take Care…Don in creepy town

Using satellite receivers (GPS), the present motions of coastal blocks with respect to stable North America can be measured (e.g., Thatcher et al, 1999; Savage et al., 2000; Khazeradze et al., 1999; McCaffrey et al., 2000).
The Sierra Nevada of California is moving northwest, and coastal Oregon north with respect to North America at 10-12 mm/yr (about 1/2 in/yr).
Part of the motion can be explained by the long-term tectonic model, above. In coastal OR and WA there is an additional eastward motion due to build up of elastic strain above the subducting Juan de Fuca plate.
The eastward motion will probably be released in future great subduction earthquakes, but the northward component is likely to be accommodated by faulting and earthquakes in the upper plate.



Follow Ups:
     ● Re: Coastal Block Motions - Petra Challus  14:38:29 - 2/1/2002  (12865)  (1)
        ● Re: Coastal Block Motions - Canie  23:20:00 - 2/1/2002  (12869)  (0)