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The ''Exxon Valdez'' oil spill occurred in Prince William Sound, Alaska, on March 24, 1989, when ''Exxon Valdez'', an oil tanker bound for Long Beach, California, struck Prince William Sound's Bligh Reef at 12:04 am〔〔(Exxon Valdez Oil Spill: Spill Timeline )〕 local time and spilled of crude oil〔〔 over the next few days. It is considered to be one of the most devastating human-caused environmental disasters.〔 The ''Valdez'' spill was the largest in US waters until the 2010 ''Deepwater Horizon'' oil spill, in terms of volume released.〔 However, Prince William Sound's remote location, accessible only by helicopter, plane, or boat, made government and industry response efforts difficult and severely taxed existing plans for response. The region is a habitat for salmon, sea otters, seals and seabirds. The oil, originally extracted at the Prudhoe Bay oil field, eventually covered of coastline,〔 and of ocean.〔 According to official reports, the ship was carrying approximately of oil, of which about were spilled into the Prince William Sound.〔〔 A figure of was a commonly accepted estimate of the spill's volume and has been used by the State of Alaska's ''Exxon Valdez'' Oil Spill Trustee Council,〔 the National Oceanic and Atmospheric Administration and environmental groups such as Greenpeace and the Sierra Club.〔〔〔 Some groups, such as Defenders of Wildlife, dispute the official estimates, maintaining that the volume of the spill, which was calculated by subtracting the volume of material removed from the vessel's tanks after the spill from the volume of the original cargo, has been underreported.〔 Alternative calculations, based on the assumption that the official reports underestimated how much seawater had been forced into the damaged tanks, placed the total at .〔 ==Identified causes== Multiple factors have been identified as contributing to the incident: * Exxon Shipping Company failed to supervise the master and provide a rested and sufficient crew for ''Exxon Valdez''. The NTSB found this was widespread throughout the industry, prompting a safety recommendation to Exxon and to the industry.〔 * The third mate failed to properly maneuver the vessel, possibly due to fatigue or excessive workload. * Exxon Shipping Company failed to properly maintain the Raytheon Collision Avoidance System (RAYCAS) radar, which, if functional, would have indicated to the third mate an impending collision with the Bligh Reef by detecting the "radar reflector", placed on the next rock inland from Bligh Reef for the purpose of keeping ships on course. This cause has only been identified by Greg Palast (without evidentiary support) and is not present in the official accident report.〔 Captain Joseph Hazelwood, who was widely reported to have been drinking heavily that night, was not at the controls when the ship struck the reef. However, as the senior officer, he was in command of the ship even though he was asleep in his bunk. In light of the other findings, investigative reporter Greg Palast stated in 2008, "Forget the drunken skipper fable. As to Captain Joe Hazelwood, he was below decks, sleeping off his bender. At the helm, the third mate never would have collided with Bligh Reef had he looked at his RAYCAS radar. But the radar was not turned on. In fact, the tanker's radar was left broken and disabled for more than a year before the disaster, and Exxon management knew it. It was (Exxon's view ) just too expensive to fix and operate." 〔 Exxon blamed Captain Hazelwood for the grounding of the tanker.〔 Other factors, according to an MIT course entitled "Software System Safety" by Professor Nancy G. Leveson,〔 included: # Ships were not informed that the previous practice of the Coast Guard tracking ships out to Bligh Reef had ceased.〔 # The oil industry promised, but never installed, state-of-the-art iceberg monitoring equipment.〔 # ''Exxon Valdez'' was sailing outside the normal sea lane to avoid small icebergs thought to be in the area.〔 # The 1989 tanker crew was half the size of the 1977 crew, worked 12–14 hour shifts, plus overtime. The crew was rushing to leave Valdez with a load of oil.〔 # Coast Guard vessel inspections in Valdez were not done, and the number of staff was reduced.〔 # Lack of available equipment and personnel hampered the spill cleanup.〔 This disaster resulted in International Maritime Organization introducing comprehensive marine pollution prevention rules (MARPOL) through various conventions. The rules were ratified by member countries and, under International Ship Management rules, the ships are being operated with a common objective of "safer ships and cleaner oceans". In 2009, ''Exxon Valdez'' Captain Joseph Hazelwood offered a "heartfelt apology" to the people of Alaska, suggesting he had been wrongly blamed for the disaster: "The true story is out there for anybody who wants to look at the facts, but that's not the sexy story and that's not the easy story," he said.〔 Yet Hazelwood said he felt Alaskans always gave him a fair shake. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Exxon Valdez oil spill」の詳細全文を読む スポンサード リンク
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