The Juan de Fuca Plate, Oregon and a Hole


The R/V Thomas G. Thompson is a 225 ft. research vessel operated by the University of Washington’s school of oceanography. It is named for the leader in studying the chemical composition of seawater.  Recently, this boat has been busy working to help solve a geological mystery surrounding one of the most poetically named geographic areas on the globe—the Juan de Fuca. 
The Strait of Juan de Fuca is a narrow strip of the Pacific Ocean that separates Vancouver Island from the state of Washington.  It is named for its explorer, Ioannis Phokas, a Greek mariner sailing for the court of Spain.  The Spanish translation of his name turns into the musical “Juan de Fuca.”  Yet it is not the Strait, but it’s underlying tectonic plate of the same name that is the focus of study by the men of the R/V Thomas G. Thompson. 
The presence of this Juan de Fuca Plate, smallest of the earth’s tectonics, off the coast of our Northwest coast has been known for as long as plate tectonics has been a source of serious study.  
Geologists also know that the Juan de Fuca Plate is subducting (sliding down under the lighter and larger North American plate).  They know that this remnant of the much larger Farallon Plate started its slow decent into oblivion when the supercontinent of Pangaea started breaking up during the Jurassic period.  We also know that such massive movement of giant sections of the earth’s surface (covered by ocean water or not) are the sources of great strain.   The stored energy of that strain is frequently dissipated in the form of earthquake or volcanic activity.  It is no accident that the Cascadia Subduction Zone, under which the Juan de Fuca disappears, is the home of Mt. Shasta, Hood, St. Helen’s.  But, despite what is known, there was also a recurring anomaly.
Mid-way down the Oregon Coast (around the area of Coos Bay, and the magnificent Oregon Dunes) there is what appears to be a hole in the Juan de Fuca Plate.   Geology is not prone to small scale corrections. Holes just don’t happen. So, the R/V Thomas G. Thompson was commissioned to start a series of seismological explorations.  Scientists began to expand data, examine, extrapolate, hypothesize and test.  The results were published in scientific journals for review last month. 
It seems that some 93 miles beneath the surface of the earth, the Juan de Fuca plate is tearing apart.  The “hole” is actually a synapse between two rending parts of a tectonic plate.  It was once thought that subducting plates did a slow, folding roll under the lifting plate.  Now it seems these plates don’t go gently into their hot good night. 
Some facts fit with common knowledge.  The Juan de Fuca has always had a line of weakness and the current tear is unzipping along that weakness. But the magma composition of the southern rift, curling away from the Cascadia zone is like the magma composition of the Yellowstone super volcano.  Are those connected in time and place? 
In a world dominated by human folly, it is nice to remember that our planet has its own concerns, timetable and agenda.  The earth is very big and very old.  In geological time, if the earth’s entire history were commuted to a single year, we humans will emerge in the last hour of the last day of that year. 
Think big, think long, and keep the faith.  Oh, and could someone please name a wine a “Juan de Fuca Red.”  It would be 93 miles deep. 

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