10,000 years of Cascadia earthquakes

10,000 years of Cascadia earthquakes

From the webpage:

The chart shows all 40 major earthquakes in the Cascadia Subduction Zone that geologists estimate have occurred since 9845 B.C. Scientists estimated the magnitude and timing of each quake by examining soil samples at more than 50 undersea sites between Washington, Oregon and California.

This chart is followed by:

Core sample sites 1999-2009

U.S. Geological Survey scientists studied undersea core samples of soil looking for turbidites — deposits of sediments that flow along the ocean floor during large earthquakes. The samples were gathered from more than 50 sites during cruises in 1999, 2002 and 2009.

Great maps but apparently one has nothing to do with the other.

If you mouse over the red dot closest to San Francisco, a pop-up says: “ID M9907-50BC Water Depth in Feet 10925.1972.” I suspect that may mean the water depth for the sample but without more, I can’t really say.

The fatal flaw of the presentation is the data of the second map is disconnected from the first. There may be some relationship between the two but it isn’t evident in the current presentation.

A good example of how to not display data sets on the same subject.

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