Tuesday, June 5, 2012

A Land Shaped by Subduction

A couple of winters ago I was working out on the Olympic Peninsula and noted that the wind was from the east, but it was not an Arctic outflow event. Perfect weather for a trip to the outer coast. I drove out to Neah Bay and the Makah Reservation. I noticed that the town of Neah Bay and the low estuary land that extends between the the town and the open Pacific Ocean. Brian Atwater came to Neah Bay in the 1980s to look for evidence of tectonic coastal subsidence. Within this low land area he began to gather evidence of large subduction earthquakes on the outer Washington coast as well as tsunami evidence. It crossed my mind that the current Makah village was likely located in an area that will be severely damaged during the next big subduction quake.

The following winter I took another trip to the outer coast further south. This time I took my inflatable kayak and paddled up a couple of estuaries. At one location I observed sandy tsunami deposits over black organic soil and at one location over what I interpreted to be a fire pit and other indications of past human habitation.

The great subduction earthquake of 1700 must have killed many coastal people. The stories of that event survived and were passed down to later generations. The event must have greatly altered coastal societies with entire communities destroyed and dislocated. The event impacted hundreds of miles of coast line from British Columbia to northern California.

I have speculated that the history of Washington State and the Pacific Northwest may have evolved very differently if the first European contacts had not come so soon after the disruption of the 1700 tsunami. A paper by Leland Gilsen (Gilsen, 2002) lays out a framework for further research and context. The subduction zone along Washington's outer coast has shaped not only the land but the population curves and societal interactions. And it will continue to do so. 

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