January 20, 2019

The Jacob Maersk was an oil tanker built in 1966 and owned by Maerskline Navigation Company, a subsidiary of A.P. Moller. Contracted by Shell, Jacob Maersk was carrying 88,000 tons of crude oil from Kharg Island in Iran. On January 29, 1975, while entering the Port of Leixões in the northern part of Portugal to discharge the oil to the Sacor Refinery, the vessel struck bottom while manoeuvring onto the berth with the aid of tugs. Heavy swell caused the vessel to repeatedly rise and fall onto the rocky seabed resulting in damage to the cargo tanks. Oil entered the engine room causing explosions and a fire which spread to the cargo holds and to oil floating on the water. A huge explosion occurred on 31st of January and the oil tanker broke into three parts. The central and the stern parts sank while the bow part remained afloat. It ran aground on the beach a few days later. The explosions destroyed all the main tanks and significant quantities of crude oil leaked from the wreck. When the fire was at its worst, the flames were 100 meters high and the sky above Porto was darkened by a thick black smoke for several days. 7 out of the 17 crew members died during the disaster, as most of them were in the engine room during first the explosion. It was estimated that between 40,000 and 50,000 tonnes of oil was consumed by fire. Much of the spilled oil was blown out to sea and 25,000 tonnes were estimated to have dispersed as a result. The remaining oil washed up on the shoreline with the heaviest contamination found in a 3-4 kilometre stretch immediately adjacent to the vessel. Containment of the oil spill began with the placement of a floating boom at the harbor entrance. A straw barrier was placed around the wreck to briefly contain the spill while boats spread dispersants. Ecological damage appeared to be limited. Dead seaweed and molluscs were found, but growth resumed shortly thereafter and populations returned to normal levels. (Sources: CEDRE/ITOPF/Wikiedia)