Spill size from Sanchi “difficult to estimate”

National authorities in the region of the sunken oil tanker Sanchi are having difficulties in establishing even approximately the size of the oil spill. Measurements have been changing, dramatically, from day to day, with strong ocean currents adding to the difficulties of accurate measurement.

Concerns were growing about the potential impact to key fishing grounds and sensitive marine ecosystems off Japan and South Korea, which lie in the projected path of the oil, according to the UK National Oceanography Centre.

The worst tanker oil spill for decades began on January 6th when Iranian tanker Sanchi, carrying about 111,000 tons of condensate and possibly 1,000 tons of bunker fuel collided with another vessel in the East China Sea. The vessel exploded, killing all 32 crew, burned and drifted for eight days, and then exploded again, before sinking.

UK National Oceanography Centre said on January 16th that “an updated emergency ocean model simulation shows that waters polluted by the sinking Sanchi oil tanker could reach Japan within a month,” adding that “revised simulations suggest that pollution from the spill may be distributed much further and faster than previously thought, and that larger areas of the coast may be impacted.” However, this view is not unanimous. Local experts, including those in Japan and South Korea, have estimated the chance of pollution reaching their coastlines as low.

China, Iran, Sanchi flag state Panama and Hong Kong signed an agreement on January 25th to investigate the sinking, based on global shipping regulations, safety investigations and standards from the International Maritime Organization.

Stakeholders were present to witness the restoration of the ship’s “black box”, said Zhi Guanglu, deputy director of the China Maritime Search and Rescue Centre, part of the Ministry of Transport, at an earlier news conference.

The black boxes for the tanker Sanchi and the freighter CF Crystal, the two vessels that collided, have been opened, the Iranian Students’ News Agency (ISNA) has reported.

Officials from China, Iran, and Panama were present when the black boxes were opened. Hadi Haqshenas, maritime affairs deputy at Iran’s Ports and Maritime Organization, said that “clarifying the ultimate results of the deciphering process takes time and it could take months”.

On the morning of January 24th a silver and white oil slick 1.8km long and 300 metres wide was discovered about 200 metres southeast of the sunken vessel. The Chinese State Oceanic Administration said that at noon an oil slick measuring 1,000 meters long and 300 meters wide was seen about 2 km from the site.

The oil from the sunken Iranian tanker Sanchi may now cover an area of as much as 332 sq km, according to the State Oceanic Administration, or as little as 21 sq km, the size of the spread reported earlier last week.

Paul Johnston, Head of Greenpeace International’s Science Unit, said that “this is an evolving situation and accurate information about the amounts of oil spilled already and likely to be spilled in the future is not available. It remains almost impossible to estimate the magnitude of the spill and what the potential environmental impacts might subsequently be”.