An invisible threat

An invisible threat

How the Sanchi oil tanker environmental disaster unfolded


On January 6, the oil tank Sanchi and cargo ship CF Crystal collided 160 nautical miles off the Shanghai coast. The Sanchi was carrying a highly flammable fuel oil, equivalent to one million barrels of oil

After crashing, the burning Sanchi was dragged south by tidal currents, before sinking in the South China Sea. Scientists hoped that while the ship was on fire, oil fumes would evaporate and a disaster could be contained, but also warned of dire consequences should the ship sink to the ocean bed

With the worst case scenario now a reality, a little-known chemical is being released into an area already hard hit by environmental issues as a result of heavy shipping and overfishing. The incident has the potential to become one of the worst environmental disasters in history

The following visual summary is compiled from official channels and international organisations

Where the tanker drifted

Regional currents dragged the Sanchi tanker about 300km (186 miles) south in nine days

SOURCE: Greenpeace, China Maritime Search and Rescue Centre and OSCAR Earth & Space Research

East China Sea oil spill: a timeline

January 2018

Collision: Saturday, Jan 6

At 8pm the Iranian oil tanker Sanchi, transporting 136,000 tonnes of ultralight crude oil to South Korea, collides with the Hong Kong-registered CF Crystal cargo ship. All 32 crew on board the Sanchi are reported missing

Oil slick: Sunday, Jan 7

An oil slick, detected within a wide circle of flames, is left by the burning, drifting tanker, according to China’s transport ministry. Rescue and cleaning ships from China and South Korea reach the site at 9am but bad weather and toxic fumes hamper their efforts. All 21 crew members of the CF Crystal are rescued as their ship is found to have suffered “non-critical” damage

No news of the crew: Monday 8

Oil leaking from the Sanchi’s hull raises the risk of an explosion and of the vessel’s sinking. At 10.30pm, the first body is recovered and sent to Shanghai for identification

Explosion: Wednesday 10

An explosion disrupts a rescue team’s effort to douse the Sanchi with foam to extinguish fires raging for the fourth day. China’s transport ministry states that no “large-scale” oil spill has been found on the sea surface. The ministry also believes the condensate oil from the tanker has been burning off so quickly that it could leave little residue. Meanwhile, Iranian officials are optimistic about the chances of the Sanchi’s crew being rescued if they “have been able to reach some place like the engine room”

Looking for survivors: Thursday 11

Workers resume their search for Sanchi survivors even as the surrounding sea flames place the stricken ship and its oil-covered decks and hull at high risk of exploding. By 5pm the search for missing crew members is expanded to cover more than 2,590 sq km (1,000 sq miles)

Drifting: Friday 12

The burning ship drifts southwest at 2.2km (1.4 miles) per hour, entering Japan’s economic zone. Fourteen rescue ships assist: 11 from China, two from South Korea and one from Japan

Discovery: Saturday 13

A salvage team finds two bodies on the Sanchi’s deck. Team members wearing respirators try to enter the ship’s living quarters but are repelled by searing heat reaching 89 degrees Celsius (192 degrees Fahrenheit) in the interior. The ship’s voyage data recorder is recovered from the bridge

The tanker sinks: Sunday 14

At 2pm the Sanchi sinks 310km (192 miles) from Naha, Japan, where the ocean is 150m (492ft) deep

Leak: Monday 15

The fire on the sea’s surface is extinguished. The oil leak is measured at 18.5km (11 miles) long by 1.8-7.4km (1-4.5 miles) wide. No survivors are expected to be found

What was the Sanchi carrying?

The Iranian oil tanker was taking condensate ultra-light crude from Iran to South Korea, according to the North American corporation ConocoPhillips the concentrate is an extremely flammable liquid containing poisonous hydrogen sulphide gas, which can cause skin irritation and be fatal if swallowed or inhaled. It is catalogued as toxic to marine life with long-lasting effects.

Marine life at risk

The chemical carried by the Sanchi is much harder to separate from water than thick crude oil. Ideally, the condensate would have burned off, minimising its spread into the marine environment. But the tanker’s sinking exposed the local ecosystem to the potent and lethal agent. Fatal to coral, it also puts whales, fish and all types of seafood at grave risk.

Active fishing area

Coastal areas in the affected region are lively fishing zones. This video shows the fishing activity of ships (in light blue) over the last month, as monitored by GFW

SOURCE: Global Fishing Watch

Shipping traffic in the South China Sea

Half the world’s oil is transported by sea on tankers. The US agency for Energy Administration Information (EIA) estimates that 15 million barrels of oil pass through the Malacca Strait daily, providing fuel to China and the rest of the region. The below map shows the total number of vessels in the past year that have transited through the area

SOURCE: MarineTraffic Global Ship Tracking Intelligence

Major oil spills

Taylor Energy’s former platform off the southern US coast in the Gulf of Mexico has continued to leaking oil since 2004, as a result of damage sustained by 2004’s Hurricane Ivan. Three ships from India (Jan 2017), Bangladesh (Dec 2014) and Philippines (Nov 2013) also continue to leak oil into the world’s oceans. Here is a global summary of major environmental disasters tied to oil tanker accidents

SOURCE: The International Tanker Owners Pollution Federation

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