Potential Risk

The northwestern coast of the United States and the southwestern coast of Canada, an area that is relatively safe tectonically? Or is it?

Over the last few thousands of years this area has seen some substainstial earthquakes, some of which have bee measured over 8.5 in magnitude and some as high as 9.5!! Since this area is home to millions of people (10 million +), the threat of a large scale seismic event would cause havoc for the whole region.

Buildings that could not withstand a large scale jolt would be destroyed within a matter of minutes.

Harbour facilities would be dessimated with the onset of a large tsunami (could be as much as 30 meteres high depending on the magnitude) created as the coast lowers 1 to 2 metres and moves 5 to 10 meteres seaward. Undersea landslides called turbidites caused by the jolt would severe communication lines leaving the area with virtually no contact with the rest of the world.

Urban centres such as Vancouver, Seattle, Portland and Victoria would be the hardest hit since these cities are located right on the shoreline.

In short the amount of destruction would be comparible to the 1995 Kobe, Japan earthquake that left over 5,000 people dead and caused a few billion dollars in damage.

How do we know that there was large scale earthqukes on the west coast?

Stratigraphy and how it is used.

Microfossils can tell alot about past quakes.

How big and how long?

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