Tragedy on Lake Toba
Idonesia’s search and rescue team believe they have located the ferry that sank in bad weather on June 18. The next step will be confirming the discovery and recovering almost 200 bodies believed to be trapped inside the vessel, a major challenge in one of the world’s deepest volcanic lakes.
JULY 2, 2018
The overloaded KM Sinar Bangun ferry sank in bad weather in Lake Toba on Sumatra island on June 18. Some 192 people are missing, most believed trapped inside the boat as it slipped beneath the waves.
The estimated number of those missing shows the ferry was overloaded nearly five times above capacity. It was also carrying dozens of motorcycles, say officials and survivors.
Ships in Indonesia often carry far more passengers and goods than they are designed for, flouting safety rules.
Lake Toba is a popular tourist destination in Northern Sumatra, Indonesia. Spread over 1,145 sq km, the lake is one of the largest in the world.
The lake fills the caldera of an ancient supervolcano that erupted about 74,000 years ago in one of history’s biggest eruptions. Many ferries connect small ports along the shore of the lake to the picturesque island of Samosir, which boasts forests, waterfalls and hills.
The harsh terrain
The lake is ringed by steep slopes that descend to the shoreline and deep below the lake surface. The caldera was formed 74,000 years ago when a super-eruption left a huge crater which filled with water over hundreds of years.
Thousands of years later, the central island of Samosir gradually emerged from the lake, rising 700 metres above the present lake surface.
With a maximum depth of around 500m, Toba is one of the deepest lakes in the world. Until around ten years ago, details of the lake bottom were essentially unknown, and it still hasn’t been fully surveyed. In 2005 and 2008, a team of geologists led by Craig A. Chesner of Eastern Illinois University studied around 600km of the lake using sonar equipment. The results of that survey formed the basis of the bathymetric data in this map.
Final resting place
The ferry sank in one of the deepest areas of the lake, near the northeastern shore. Authorities have located what they believe to be the remains of the vessel using sonar equipment.
“If the sunken ferry is sitting in 450 m of water, it is not likely to be perched on the steep caldera wall, but instead probably lies on the relatively flat floor of a narrow trough not far from the base of the wall.” said Chesner.
The ferry is thought to be resting at 450 metres underwater. That’s 10 times deeper than the Sewol, a South Korean ferry that sank in 2014 killing 304 people. It took almost three years to raise the wreckage of the Sewol. However, this is nowhere near the depth of some wrecks in the open ocean such as the Titanic.
The search operation
Search teams using a remotely operated underwater vehicle (ROV) found bodies and debris from the ship at depths of 450 metres during their underwater search, and the wreckage was later found. However, the two-week search operation to retrieve the bodies of nearly 200 passengers was called off on July 2, two weeks after the ferry sunk.
A troubled past
Indonesia frequently suffers boat sinkings, with basic safety rules often flouted and vessels overloaded. According to Baird Maritime Passenger Vessel Accident Database, there have been over 600 (645) passenger vessel accidents that cost over 33,000 (33,703) lives since 2000. Indonesia accounts for more of these than any other country, making up nearly a quarter of incidences, followed by the Philippines, Bangladesh, and China. The poor track records of these nations contribute to Asia’s overall tally of almost 56% of accidents globally.
Here are all passenger vessel incidents since 2000 that resulted in the death of passengers. Indonesia has the highest number of incidents recorded by any country, while rest of Asia is home to nearly half of the incidents. Other countries mostly include incidents from Africa and Central America.
About 51% of accidents resulted in the vessel sinking.
In around 17% of these incidents, overloading was a contributing factor to the cause of the accident. This is thought to be a factor in the Lake Toba sinking, with the boat carrying five times its registered capacity.
Accidents with overloading account for a larger portion of deaths however. Almost 14,000 people have died in those incidents since 2000. That’s around 41% of the total deaths in the same period.
Notes: Bathymetry data for Lake Toba was collected using single beam sonar in 2005 and 2008 by C.A. Chesner, M.T. Dolan, and S.P. Halsor. This data was used to construct the bathymetry map by permission of Craig A. Chesner. Original bathymetry map and profiles published in Chesner (2012).
Sources: Baird Maritime Passenger Vessel Accident Database; Reuters; Chesner, C.A., 2012, The Toba caldera complex, Quaternary International, v. 258, p. 5-18, doi:10.1016/j.quaint.2011.09.025; Maps4News; Rogate Beach Hotel
By Simon Scarr, Chris Inton, Jin Wu, Gurman Bhatia and Jessica Wang | REUTERS GRAPHICS
Additional reporting by Fergus Jensen
Source : reuters graphic