Bill Sherrod: Active tectonics in South Puget Sound

Shallow plates will be the focus of his talk.

Some of the strain from the Cascadian subduction zone offshore is pushed onshore onto North America. Not every fault onshore is active. None of them have produced a massive earthquake historically. The closest was in the 1940s (?) in Canada. There was another one in the 1700s on the east side of the mountains.

Again, this shallow faults are not particularly active.

They can measure how active particular faults are by examining the sediment.

Olympia fault, near Totten and Eld Inlet, caused an earthquake 1,000 years ago, which caused the local shoreline to slump. They can find tree stumps that were quickly moved into tidelands. The area sank during an earthquake about 1100 years ago.

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