How many oil spills are caused by rigs and how many by tankers?
Tanker accidents have accounted for most of the world’s largest oil spills. They are less frequent than other kinds of oil spills, such as pipeline breaks, but typically involve large volumes of spilled oil relative to other kinds of oil spills. Between 1971 and 2000, tankers and barges were responsible for 45 percent of the volume of oil spilled in U.S. waters, according to a 2002 U.S. Department of the Interior Minerals Management Service report. In that same period, pipelines were responsible for 16 percent of the volume of oil spilled in U.S. waters. This includes both onshore and offshore pipelines, though onshore spills accounted for most of the pipeline spillage into U.S. waters — 92 percent or more in each decade. Between 1971 and 2000, U.S. Outer Continental Shelf (OCS) offshore facilities and pipelines accounted for only 2 percent of the volume of oil spilled in U.S. waters. The amount of oil from different types of spills can vary from year to year.
