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NOAA has run a model using OSCURS (Ocean Surface Current Simulator). The results are shown here. Year 1 is in red, Year 2 in orange, Year 3 in yellow, Year 4 light blue, Year 5 violet. (Courtesy of J. Churnside, NOAA; created using Google.)
Marine debris from the March 2011 tsunami in Japan has caused concerns about impacts to Alaska and the west coast. NOAA has set up a website focused on Japan tsunami marine debris with updated information, FAQ, and short videos.
1) How much debris is there?
The Japanese government estimated that the tsunami created a total of 25 million tons of debris, but there is no confirmed estimate of how much of that went into the water. Of the amount that washed out to sea, data and experience from similar events shows that much of the heavier debris is likely to have sunk in the nearshore area. The remaining debris began to disperse with ocean currents and weather, generally moving east.
Right after the event, tsunami debris concentrations or bands could be seen by satellite sensors, but by a few weeks after the event the debris had spread out to the point where sensors could no longer pick up the more dispersed objects. NOAA is working to get access to higher resolution satellite data and targeted as well as opportunistic overflight inputs to search for debris at-sea.
2) What type of debris is out there?
The tsunami impacted an area with varied infrastructure, so what was washed to sea is expected to be a wide range of items – household and consumer goods, construction and industrial materials, fishing and maritime equipment, etc. The exact composition is unknown, and likely to vary over time and distance as the debris weathers. This makes it difficult to differentiate “tsunami debris” from the debris that unfortunately hits Alaskan (and other) shorelines all the time.
3) Is the debris radioactive?
Consensus of scientists across the agencies NOAA has consulted with is that debris contamination is HIGHLY unlikely. This is based on several reasons, primarily that the debris would have been too far from the Fukushima reactor to have been in contact with radiation, both because the radiation leaks began after debris would have begun moving off the coast, and because the tsunami impact area included areas far from the reactor site.
4) What to do if I see potential tsunami-related debris?
NOAA is asking that people report significant sightings of debris that could be linked to the Japan tsunami to an email address created for the purpose – disasterdebris@noaa.gov, including as accurate a description as possible of what you saw, and where you saw it, as well as the potential linkage to the tsunami. NOAA is also working with partners to put together a set of general basic guidance for handling of potential tsunami debris, which will be posted on the website soon.