The 9.0 earthquake of March 11, 2011, generated a 130-foot wave that devastated 217 square miles of Japan’s coast, resulting in well over 15,000 deaths and an estimated 25 million tons of debris. However, “there is no confirmed estimate of how much actually went into the water. There is also little information on what types of debris (boats vs. trash vs. appliances) went into the water. Immediately after the event, satellite sensors focused on the area around Japan picked up tsunami debris, but by April 14, the debris had dispersed to a point where the sensors could no longer detect it. This doesn’t mean it has vanished – we just can’t see it with lower resolution satellites, making it very difficult to locate. The debris is no longer in a ‘debris field.’ Rather, there are many items scattered across a large area of the North Pacific” (source).
More than nine months after the disaster, oceanographers have located what is believed to be the first debris washed up onto the shores of the West Coast of the US. “A half dozen large buoys suspected to be from Japanese oyster farms have appeared near Yakutat at the top of Alaska’s Panhandle and may be among the first debris from Japan’s devastating tsunami last year. Debris that’s not out of the water is crossing the Pacific at about 7 miles per day; the main body of debris is in the latter category and is not expected to reach West Coast shores, including Alaska, before 2013. Federal, state and private entities will rely on beachcombers, pilots, and mariners to report what is hitting Alaska waters and shores” (source).
“From entire segments of wooden homes, furniture and appliances to cars and boats, the rubbish islands are creating growing concern due to environmental pollution as well as shipping hazards. The possibility of human bodies being included in the debris is also high, bearing in mind the thousands of victims of the disaster who are still missing, believed to have been swept out to sea. The main body of floating tsunami debris is expected to hit US shores in around a year, stretching the length of the coastline from California to Alaska, according to experts” (source).
“One thing is certain: the debris is hazardous to navigation, marine life, and, when washed ashore, to coastlines,” said a press release from the International Pacific Research Center at the University of Hawai`i. Researchers thus far have largely depended on already deployed floaters and computer current and wind models to make estimates of the debris field’s location. They’ve been helped by reports from a few ships that have transited the field. The models suggested that debris could be arriving in the Northwestern Hawaiian Islands this winter, hitting Midway Atoll and the islands of the Papahānaumokuākea National Marine Monument. Ship reports as early as September showed the debris field just 250 miles northwest of Midway.
Teams from the University of Hawai`i at Mānoa and at Hilo, the Scripps Institution of Oceanography, and the Ocean Recovery Alliance developed a plan to deploy a drifter array across the front of the debris field. They developed 11 satellite-tracked buoys that are designed to mimic the motion of different kinds of debris and put them in the water between Midway and the debris field. The satellite signals from the buoys will help researchers understand how the field is moving in the local currents of the region. In a decidedly lower-tech program, they also deployed 400 wooden blocks in the water, each branded with information on how people finding them can respond. ‘If boaters, fishermen and beachgoers find these blocks and contact the scientists by the information on the blocks, they will also increase understanding of the motion of debris and currents in this remote region,’ the release said” (source).
Article by Bill Norrington
