Two weekends ago I spent the day at Cape Lookout State Park. I arrived early in the morning to catch low tide and enjoyed wandering the southern section of Netarts Spit. The ocean was gentle that day but signs of the ocean’s immense power surrounded me. The entire campground is only a few feet above sea level and large portions of it have eroded away in the past few years.

The state has reinforced sections with massive sand bags but even those cannot withstand the fierce winter storms. This past January, storms overtopped the spit and swept debris some 300′ into the picnic area. While damaging, that is nothing compared to the chaos visible at the south end of the spit. As the ground rises to meet the Cape Lookout headland the cliff face contains graphic evidence of destruction from the tsunami of 1700; trees twisted and encased in a layer of black soil (see photos below).

On January 26, 1700 an earthquake, rated around 9 on the Moment Magnitude Scale, struck in the Cascadia subduction zone along the Pacific Northwest Coast. The resulting tsunami not only overtook forests and carried debris far inland on the North American continent but it caused damage in Japan some 4800 miles away.

In a way it is a good thing that the tsunami reached Japan as it enabled geologists to pinpoint the exact date of the event. Native Americans living in the Pacific Northwest had oral histories testifying to the extent of the damage (entire villages inundated and destroyed) but these lacked the precision of a written record.

Dendrochronology helped narrow down the timeframe, as the last growing season of the massive trees was 1699, which put the event somewhere between October 1699 and February 1700. That information, cross-referenced with written accounts of a tsunami reaching Japanese shores, led researchers to the exact date of the earthquake.

The area is still active, with the Juan de Fuca plate sliding under the North American plate at a rate of roughly 2.5 inches each year. On the plus side, this action causes enough uplift to parts of Oregon and Washington that it counteracts the annual rise of sea level. Yay!

The downside is that this convergent plate boundary has geologists extremely worried. Based on previous intervals (of roughly 500 years) the region is due for a massive quake. If that occurs, all the sand bags in the world couldn’t protect Cape Lookout State Park. FEMA’s outlook for the region is dire, “Our operating assumption is that everything west of Interstate 5 will be toast.” Now there’s a cheery thought!

Fortunately, on the day I visited, Huecha Omeyocan, a group dedicated to honoring MesoAmerican rituals, held a ceremonial dance blessing the coast. Perhaps their efforts will ward off the Big One for a few hundred more years…

Cape Lookout Headland

Mighty Root Systems

Isopod

Gooseneck Barnacle with Extended Cirri

Limpets and Barnacles

Shore Crab, Green and Maroon

Common Periwinkles with Eggs

Rockweed

Sea Cave View

Evidence of Tsunami 01-26-1700

Uprooted Trees, Damage from 01-26-1700 Tsunami

Debris Flow from 01-26-1700 Tsunami

Huecha Omeyocan Blessing the Ocean

Huecha Omeyocan Dancers