Wednesday, December 28, 2011

Japanese Tsunami Debris: Where Is It? Worst-And Best-Case Scenarios

Debris from the tsunami that devastated Japan in March could reach the United States as early as this winter, according to predictions by NOAA scientists. However, they warn there is still a large amount of uncertainty over exactly what is still floating, where it's located, where it will go, and when it will arrive. Responders now have a challenging, if not impossible situation on their hands: How do you deal with debris that could now impact U.S. shores, but is difficult to find?
Credit: NOAA

Federal Agencies Join Forces

To learn more about the tsunami debris, NOAA researchers have been working with the U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and other partners to coordinate data collection activities.

NOAA and its partners are also coordinating an interagency assessment and response plan to address the wide-range of potential scenarios and threats posed by the debris.

“We’re preparing for the best and worst case scenarios — and everything in between,” says Nancy Wallace, director for NOAA’s Marine Debris Program.

As the tsunami surge receded, it washed much of what was in the coastal inundation zoneinto the ocean. Boats, pieces of smashed buildings, appliances, and plastic, metal, and rubber objects of all shapes and sizes washed into the water — either sinking near the shore or floating out to sea. The refuse formed large debris fields captured by satellite imagery and aerial photos of the coastal waters.

The Japanese government estimated that the tsunami generated 25 million tons of rubble, but there is no clear understanding of exactly how much debris was swept into the water nor what remained afloat.

What remains of the debris?

Nine months later, debris fields are no longer visible. Winds and ocean currents scattered items in the massive North Pacific Ocean to the point where debris is no longer visible from satellite. Vessels regularly traveling the North Pacific have reported very few sightings. Only two pieces have been clearly linked to the tsunami.

NOAA is coordinating new interagency reporting and monitoring efforts that will provide critical information on the location of the marine debris generated by the tsunami. Ships can now report significant at-sea debris sightings and individuals or groups can request shoreline monitoring guides at

Where is it?

Computer models run by NOAA and University of Hawaii researchers show some debris could pass near or wash ashore in the Northwestern Hawaiian Islands (in the Papahānaumokuākea Marine National Monument) as early as this winter, approach the West Coast of the United States and Canada in 2013, and circle back to the main Hawaiian Islands in 2014 through 2016.

Researchers caution that models are only predictions based on location of debris when it went into the water, combined with historical ocean currents and wind speeds.

Conditions in the ocean constantly change, and items can sink, break down, and disperse across a huge area. Because it is not known what remains in the water column nor where, scientists can’t determine with certainty if any debris will wash ashore.

Worst- and Best-case Scenarios

The worst-case scenario is boats and unmanageable concentrations of other heavy objects could wash ashore in sensitive areas, damage coral reefs, or interfere with navigation in Hawaii and along the U.S. West Coast. Best case? The debris will break up, disperse and eventually degrade, sparing coastal areas.

Debris will not go away completely, even in a best-case scenario. Marine debris is an ongoing problem for Hawaii and West Coast states, where garbage and other harmful items regularly wash up on beaches, reefs and other coastal areas.

What Else is NOAA Doing?

NOAA has convened experts to review available data and information from models and provide their perspectives on debris fate and transport. They are gathering information on significant sighting of marine debris in the North Pacific through NOAA’s Office of Marine and Aviation Operation’s Pacific fleet, the NOAA Voluntary Observing Ship Program, which includes industry long-haul transport vessels, as well as the NOAA Pacific Island Regional Observer Program and their work with the Hawaii longline fishing industry. NOAA is also working with the U.S. Fish and Wildlife Service and the State of Hawaii on shoreline debris monitoring in the Papahānaumokuākea Monument.

Audio Podcast: The powerful Japanese earthquake and resulting tsunami in March, 2011, washed untold tons of marine debris into the Pacific Ocean. Carey Morishige, Pacific Islands Regional Coordinator for the NOAA Marine Debris Program, explains where this debris may be, where it's heading, what's being done about it, and what you can do to help.

Audio Transcript
You're listening to Making Waves from NOAA's National Ocean Service. I'm Troy Kitch.

This Spring's devastating earthquake in Japan registered in at a magnitude of 9.0, ranking it among the top five largest earthquakes in the world since modern recording-keeping began in 1900.

The quake triggered powerful tsunami waves, reaching heights of up to 24 feet high and traveling miles inland along the Japanese coast near the epicenter.

As the tsunami receded, mountains of debris were carried back into the sea. Boats, buildings, appliances, plastics, metals, wood, rubber … all shapes and sizes of debris either sank near the shore or floated away.

Today, we're going to take a look at what we know about the fate of the debris that washed into the ocean last March. How much is out there? Where is it now? When is it going to make landfall? Is it dangerous?

To help us answer these questions, we're joined on the phone by Carey Morishige, the Pacific Islands Regional Coordinator for the NOAA Marine Debris Program. I reached Carey at her office in Honolulu.

I began by asking the obvious question: where is all of this marine debris now, nine months after the Japanese earthquake and tsunami?

[Carey Morishige] "We don't know exactly where. NOAA worked with NASA to get satellite imagery very soon after the tsunami and we were in fact able to track the debris field -- some of the pictures that folks have probably seen in the media of the large patches of wood and other debris. Those existed very soon after the tsunami, but as of April 14, we were not able to track that debris anymore because of the fact that it dispersed so much, the satellite imagery we have access to right now is not able to detect a single piece of debris floating in the ocean."

Carey said that NOAA has received a few floating debris sightings from ships – things like plastic bottles, appliances, and wooden boxes – but because of the way the debris has dispersed in the ocean over time:

[Carey Morishige] "We don't have a good understanding at this point of the debris types that are still afloat out in the North Pacific, as well as the quantity of debris that might still be floating."

And because we know so little, she said it's really hard to say how dangerous this marine debris might be.

[Carey Morishige] "I could attempt to characterize how dangerous this debris is if we knew better what type of debris was coming. We're preparing for all types of debris, and for human health and safety, we will continually be monitoring things such as radioactivity, though radioactivity of this debris is highly unlikely because it was washed out prior to the Fukishima disaster. We'll also be on the look out for any debris items that contain hazardous materials, and we're working on protocols to deal with all of that. But without a good understanding of the specific types of debris that are still out there, I really can't estimate the danger of it."

If you're surprised to learn that we know so little about the tsunami debris, you have to bear in mind that the Pacific Ocean is truly massive – it covers a third of the globe.

And the ocean is a really dynamic environment. If you have a mental image of debris from the tsunami floating along in a giant patch, it's not like that at all. While there are certainly chunks of debris afloat, it's spread over a vast area … and some of it is floating below the surface, and a lot of it has likely been broken into small bits by the power of sun, sea, and weather.

Here's what we know for sure at this point: the path of the debris is largely determined by currents and wind. And is it travels along, it's fanning out into a wider and wider area.

Carey said that knowledge of ocean currents, along with other variables such as historical winds, and weather, have allowed scientists to create sophisticated computer models to predict roughly where the leading edge of this marine debris is likely to be at a given time.

"It's not real-time, it's a computer model that uses algorithms to try and predict the movement of marine debris."

Here's a rough idea how that movement works. If you look at the North Pacific Ocean, there are four major currents that form what's called the North Pacific Subtropical Gyre. These currents form a giant circular flow – from Japan across the North Pacific to California … down the California coast, then back across the Pacific closer to the equator, and finally back up towards Japan. Carey said this is generally the path that the debris is following:

[Carey Morishige] "… it's going to go from Japan, across the North Pacific, skimming the top of the Northwest Hawaiian Islands, down the West Coast with the California currents, and then back across the North Pacific towards the main Hawaiian islands."

How quickly will this happen? Well, Carey said the computer models predict the debris will likely reach the California coast sometime in 2013, then head back across toward the main Hawaiian islands, reaching the islands sometime around 2015. But the first landfall for the debris is imminent.

[Carey Morishige] "…the debris is quite dispersed at this time, but it is making its way across the North Pacific current and it's fairly close to the Northwest Hawaiian Islands." (c1)

How close? She said that debris is expected to reach the Northwest Hawaiian Islands as early as Winter this year – pretty much right now. So now the challenge is to detect it.

[Carey Morishige] "The best possible information we could get would be real-time information from overflights or from very high resolution satellite imagery – and then we would know for sure that what our models are predicting is actually where the debris is ending up."

This is another case where it helps to get a handle on just how big the Pacific Ocean is. When you think of Hawaii, you probably think of the chain of inhabited islands that stretch from the Big Island of Hawaii to Kauai – the main Hawaiian islands. But where the debris is expected to soon hit land is in the northern reaches of the Northwest Hawaiian islands … a chain of uninhabited islands that stretch for 1200 nautical miles to the northwest of the main islands -- that's about the distance from San Diego, California, to Vancouver in British Columbia.

It's not an area that's easy to get to.

[Carey Morishige] "It is more complicated than that. Because it's a protected area and it's so far away from the inhabited main Hawaiian islands, or the West Coast [of the U.S.] or really anywhere … the furthest archipelego from a big land mass, I think in the world. You know, logistics for debris removal, debris prevention efforts are logistically very difficult and because of the travel distance to get to the Northwest Hawaiian Islands, very expensive."

So it's complicated, but that's not to say that nothing is being done. I asked Carey if she could sum up how this problem is being addressed. She said there are several pieces to the puzzle – there's the modeling to try to figure out where the debris is going; there's the observational piece to nail down where the debris actually is; and then there's the planning effort to address what to do once debris reaches shores. Right now, efforts are of course focused on the area in the Northwest Hawaiian Islands where the marine debris is likely to hit first. The role of NOAA's Marine Debris program is to help keep everyone moving in the same direction to meet this challenge.

[Carey Morishige] "So we're working with a lot of regional partners out here, including other NOAA offices and programs, obviously the co-trustees of thePapahānaumokuākea Marine National Monument, which includes U.S. Fish and Wildlife Service, NOAA as well as the state of Hawaii. EPA has also been involved, various state agencies, and a lot of the academia as well as industry is interested in getting involved as well. The numbers that have gone out in the media about 20 million tons of debris – those numbers are unfounded. We don't know how much is out there. We don't have a good understanding of what types, but we are doing everything possible to build that understanding, and at the same time, not sitting on our hands and starting those planning efforts now."

Carey said that the public can help address this problem, too. If you happen to be traveling in a vessel anywhere in the North Pacific Ocean and spot floating marine debris, the Marine Debris office has an email where you can report what you saw, when you saw it, and where it's located. We'll have that address in our show notes.

And here's another way you may be able to help. For those who live anywhere along the West Coast, Hawaii, or Alaska, the Marine Debris program is looking for help to track marine debris over time along the shoreline. In a nutshell, this involves regular visits to an area to carefully catalog the marine debris you find. If you're interested in joining this effort, you can send a note to that same email address – -- to request a copy of NOAA's marine debris shoreline survey field guide.

So this is certainly a complicated problem … and one that will be with us for many years to come. What's the worst case scenario? Well, there's a possibility that boats and other heavy objects could wash ashore in sensitive areas, damage coral reefs, or interfere with navigation in Hawaii and along the West Coast. The best scenario? That most of the debris will break up, disperse and eventually degrade, sparing coastal areas.

Either way, Carey stressed that this isn't a one-time problem. Marine debris is a really big ongoing global issue. She said in the state of Hawaii:

[Carey Morishige] "We see marine debris coming ashore on all of our islands every single day. So it's just not this one-off event and we don't typically get marine debris and now we are. We always get marine debris. It has been a problem before the tsunami and likely will be a problem after all of this tsunami debris."

So marine debris is with us stay … and the debris from the Japanese tsunami won't go away completely … even in the best-case scenario. The good news is that NOAA and its partners know quite a lot about marine debris and its challenges, experts are working around the clock to meet this problem head-on more about, and continue working to protect our natural resources and coasts.

That was Carey Morishige, the Pacific Islands Regional Coordinator for the NOAA Marine Debris Program. I reached Carey at her office in Honolulu.

Visit us at for more on the Japanese tsunami marine debris program, and to learn much more about the global marine debris problem.

We also hope you'll visit us at

If you have any questions about this week's podcast, about the National Ocean Service, or about our ocean, send us an email at

This is Making Waves from NOAA's National Ocean Service. See you in two weeks.

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