Submarine volcano

Over the years, I've climbed four of the five volcanic peaks in Washington -- Mt. Rainier (twice), Glacier Peak (twice), Mt. Adams, and Mt. St. Helens (once before the eruption, several times to the crater edge since).  I was with a group climbing the remaining volcano -- Mt. Baker -- when one of our group developed problems half-way up, and we had to turn around and help her back down.

Mt. Olympus is not a volcano, but -- along with the rest of the Olympic range -- a part of the remnants of Pacific Ocean sea floor that were jammed up against the continent by the eastern motion of the Pacific and/or Juan de Fuca Plates -- remnants that failed to dive under the North American Plate like most of the moving sea floor, and instead were scraped off and ended up above ground.

But even Olympus -- though not a volcano -- apparently resulted indirectly from volcanic activity.  It ended up above the North American plate, rather than subducting beneath it, because it came from a portion of the moving plates that had been built up volcanically to a high elevation -- a "seamount" -- while still far under the surface of the ocean.

Which brings me to the lead article in today's Seattle Times. About 300 miles off the coast of the Northwest Corner, at the junction of the Pacific and Juan de Fuca tectonic plates, one finds the Axial seamount, a volcano rising about three thousand feet above the ocean bottom.  The article points out that -- since it lies nearly a mile under water -- the volcano resembles the shield volcanos of Hawaii more than the pointy peaks of the Cascade range, and results from a flow of magma rather than sudden explosions.

Nevertheless, even non-explosive eruptions are fascinating to scientists for what they reveal about volcanic activity in general.  A week ago, during a 24 hour period, 8,000 small earthquakes were recorded in the area, caused by the movement of magma beneath the sea floor.  These quakes would suggest the imminence of an eruption, but so far an eruption has not been detected.

The Times article was devoted primarily to a discussion of the sophisticated monitoring devices maintained by the University of Washington, and the University scientists' observations based on the resulting data.  But for us non-geologists, the article was fascinating because it brought to our attention the existence of this nearby display of the Earth's dynamism.

This week, the disaster in Nepal has shown one possible effect of the constant movement of tectonic plates.  The Axial Seamount shows us another, one far more benign in terms of its effect on human population. 

Axial is only 3,000 feet high, a baby volcano compared with, say, Mt. Rainier.  Fortunately, it lies far outside the jurisdiction of the State of Washington, so I feel absolutely no compulsion to add it to my scorecard of ascents by attempting to climb it.