VIENNA – On April 20, an explosion on Deepwater Horizon, a British Petroleum (BP)- operated oil rig in the Gulf of Mexico, led to the most publicized oil spill in decades. Another blowout in the same waters 31 years ago, farther south on the Mexican side of the Gulf, turned into the largest peacetime oil spill ever.
The platform where that accident happened, called Ixtoc 1, was operated by Pemex, the state-owned Mexican oil company. The two accidents and the spills they caused have a number of similar features, although marine oil spills in general have profoundly changed in character in the three decades between the two events.
Oil tankers used to be responsible for the bulk of oil that was spilled. Tank-washing gave rise to a huge number of small spills, and tanker accidents such as those involving the Torrey Canyon, Exxon Valdez, Metula, and St. Peter resulted in huge, concentrated spills. Blowouts were not infrequent, but most occurred on land or in shallow water, and most could be stopped relatively easily.
The ban on tank-washing, technical features such as double hulls and sectioning of tanks, introduction of one-way sea lanes and, most important, the use of Global Positioning Systems, have greatly reduced the amount of oil entering the sea from tankers.