The Tohoku tsunami that struck Japan in March 2011 swept untold tons of material ranging from personal belongings to entire buildings into the Pacific ocean. As we reported in May, researchers using computer models of ocean currents predicted that the debris would take several years to arrive on the west coast of North America.
But as early as December 2011, beachcombers in Neah Bay, WA and on Vancouver Island began reporting tsunami debris washing up on their coastline. While most debris is expected to move at about 7 mph, larger items pushed along by the wind may reach 20 mph. But there is debate over whether the reported flotsam and jetsam, which ranges from lumber to bottles, is linked to the tsunami, since debris from Japan frequently washes up along west coast beaches. (Generations of beachcombers have collected glass Japanese fishing floats, for example.)
No one is certain how much material was washed into the ocean by the tsunami surges. Initial estimates of 5 to 10 million tons are now believed to be too conservative. Some researchers believe there is a debris field the size of California where currents have corralled the material.
Some scientists contend that most of the debris from the tsunami will break up and sink before reaching the shores of Hawaii and the west coast of North America. Others hypothesize that unmanageable concentrations of large objects such as damaged boats, vehicles, household appliances, and parts of buildings may damage sensitive areas. A few ships have reported spotting large items floating in mid-ocean.
Researchers from institutions and agencies around the world are predicting and studying the movement of the items in hopes of learning more about ocean water movements. But unlike research buoys released expressly for study or cargoes of plastic toys lost overboard in storms, the rubble of the tsunami is a reminder of a tremendous loss of human life.
Some human remains are likely to wash ashore, and there is concern about toxic waste as well. Because the trouble with the Fukushima power plant began after the tsunami waters receded, government agencies do not anticipate problems with radioactive materials washing ashore.
NOAA’s Marine Debris program web site has a page complete with a video about how agency researchers are monitoring the situation and trying to come up with solutions that cover every contingency.
But it seems that only time and tide will eventually answer our questions about what will wash ashore in the wake of Japan’s 2011 tragedy.