wall made from dock ruined by 2011 tsunami

Photo: A wall in Depoe Bay, Oregon commemorates the 2011 tsunami. 

On March 11, 2011, an earthquake so powerful that it shifted the earth on its axis struck northeastern Japan, unleashing a giant tsunami, killing at least 15,894 people and destroying the homes of 150,000. The tsunami caused the Fukushima Daiichi Nuclear Power Plant to fail, causing 10,000 people to evacuate their homes and sending radioactive isotopes toward the western shores of North America. All told, the Tōhoku quake, tsunami, and nuclear power plant failure displaced more than 450,000 people.

The disaster also had effects far across the ocean, as the tsunami’s waves continued on to North America.

The tsunami damaged some North American boats and harbors. However, the most widespread and lasting impacts outside of Japan seem to have come not from the tsunami itself but from what its waves carried across the ocean.

An estimated five million tons of debris washed ashore on North America’s Pacific coasts. A four-year study recorded nearly 100,000 individual items.

What Washed Ashore

In Alaska, plastic bottles, building insulation, marine buoys, and a soccer ball that was later reunited with its owner littered beaches. Offshore, the U.S. Coast Guard sunk the Ryou-Un Maru, a Japanese fishing trawler set adrift by the tsunami, because it was a hazard for other boats and ships.

Tsunami debris reaching British Columbia included a motorcycle, as well as small boats, fishing floats, lumber, toothbrushes, plastic bottles, life jackets, and an enormous fender from an ocean-going ship.

Likely tsunami items in Washington state included docks, tires, refrigerators, a boat containing live fish that hitched a ride across the ocean, and a bottle of cough syrup. Northern Washington saw a 1,000% increase in marine debris.

In Oregon, a 188-ton dock arrived on Agate Beach, bearing 118 species of marine life that were native to Japan, not North America. A fishing trawler with about 20 live yellowtail jackfish, which are normally found in the ocean near Japan, turned up off the central Oregon coast.

California’s shores received much less of the tsunami debris than other areas. Most notably, a small boat was traced back to a Japanese high school and returned to Japan.

The Great Migration

The tsunami resulted in what looks to be the longest, largest marine migration on record. Two hundred and eighty-nine different species of marine wildlife native to Japanese coastal waters hitched a ride across the ocean on wreckage from the tsunami. Japanese fish, algae, barnacles, limpets, mussels, oysters, scallops, crabs, sea anemones, sea cucumbers, sea slugs, marine worms, and others turned up in Hawaii and on the west coast of North America from Alaska to northern California. Six years after the tsunami, they were still arriving and may continue to arrive with the spring tides.

Whether and which of these animals may become established in North America as a result of the tsunami is still unknown. As of October 2018, none of the 84 species of algae and cyanobacteria that migrated over had become established. But this region is roughly 2,500 miles in length, so who’s to say there isn’t some small colony of life tucked away somewhere within it that wouldn’t be there but for the tsunami.

In earlier times, far fewer marine creatures made it across the ocean while still alive because what they were drifting on disintegrated and sunk. But now most everything is plastic, and plastic lasts much longer in the open ocean than the wooden boats and other objects of the past.

Could Your Belongings Visit Japan without You?

The flow of tsunami wreckage and the marine life that comes with it is not a one-way street. An enormous North American earthquake in 1700 sent tsunami waves to Japan.

If you live along the Pacific coast anywhere from northern California to British Columbia, you probably know that you should be preparing for a similar earthquake to happen again.

Depending on the map I consult, I live on or next to land expected to be underwater for a while after the next Big One on the Cascadia Subduction Zone.

It’s a curious thing to look around one’s home and wonder if anything in it could make it across the ocean, serving as a life raft for wildlife or algae. I own no soccer balls, so my money’s on plastic food storage containers and their lids: small, light, and seemingly indestructible.