From: Andy Soos, ENN
Published December 29, 2011 09:16 AM

Tsunami Debris

Anything that goes into the ocean will eventually either sink or float. 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? Just another garbage wave to worry about but one that is not directly a result of man's bad habits.

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A tsunami is a huge volume of moving seawater.  These giant waves can travel for thousands of miles across the sea and still have enough energy and force to destroy buildings, trees, wildlife and people.

If you throw a stone in a pond it will create a series of ripples.  A tsunami is just like those ripples but the disturbance that sets them moving is much greater than a small stone.  It can be triggered by an undersea earthquake, landslide or volcanic eruption.

In March 2011 an underwater earthquake triggered a tsunami which hit Japan’s north-east coast.  The earthquake was the most powerful ever recorded in Japan causing a 30 foot tsunami wave to hit the city of Sendai and further devastate several coastal communities.  This created tons and tons of shattered city stuff.

As the tsunami surge receded, it washed much of what was in the coastal inundation zone into 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 initially large debris fields captured by satellite imagery and aerial photos of the coastal waters.

Nine months later, debris fields are no longer clearly 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 sightings have been clearly linked to the tsunami. 

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.

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 and sink, sparing coastal areas but adding to deep sea sediment.

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

For further information:  http://oceanservice.noaa.gov/news/features/dec11/japan-tsunami-debris.html

Photo:  NASA

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