More on Submarine Cables | Motohiro Tsuchiya, Vice-President / Professor, Graduate School of Media and Governance
2022.01.25
Tonga's submarine cable was severed. As I've written before , I love submarine cables. I have been thinking about them for over a quarter of a century.
What are submarine cables? How are they repaired? Could something like this happen in Japan? I was interviewed a few times after the Tongan cable was severed.
Tonga's submarine cable was connected nine years ago, in 2013. According to the Submarine Cable Map provided by TeleGeography, Tonga has only one international line: an 827-kilometer cable connecting it to Fiji. It is a major problem that this cable has been severed.
However, the Tongan cable was also severed in January 2019. It is believed that an anchor from a foreign ship struck the cable. While repairing a submarine cable typically takes two weeks, service was restored in 12 days on that occasion.
Restoring a severed cable is a laborious process. Spare cable kept in storage is loaded onto a special vessel called a cable-laying ship, which then heads to the site. Then, the ship searches for the broken cable by dragging a large hook-like grapnel along the seabed. Once found, it is pulled up onto the ship. Since an anchor could reach it, it probably wasn't at a great depth. The cable is then re-spliced on board the ship. The optical fibers, each thinner than a human hair, are fused together one by one, and the metal and polyethylene armor is reapplied. After confirming a successful connection, it is returned to the seabed.
What about this time? The problem is the depth at which it was severed. If it's at a depth of tens to thousands of meters, it will take even longer. There is also likely volcanic ash accumulated on the seabed, which could complicate the search for the cable. In that case, it will likely take more than two weeks.
As has already begun, minimal international communication can be restored using satellites. However, this cannot match the traffic volume provided by submarine cables. In Japan's case, 99% of international communications rely on submarine cables. The majority was likely carried by cable in Tonga's case as well. It is impossible to cover all of that with satellites.
Could something like this happen in Japan? It is unlikely that all of Japan's cables would be lost due to a natural disaster. It is hard to imagine an earthquake, tsunami, or submarine volcanic eruption occurring simultaneously across all of Japan. Japan is connected by more than 20 submarine cables.
During the 2011 Great East Japan Earthquake, many cables were severed. However, most people were likely unaware of this fact. Although many of the cables connected to Chiba and Ibaraki were cut, communication traffic with the United States and Asia was maintained using cables connected to Shima.
Of course, a lesson from the Great East Japan Earthquake is to expect the unexpected. If many cables were lost simultaneously for some reason, it would affect sectors like finance that rely on high-speed trading. We must also ensure that such things are not done deliberately by human hands.
The novel "2034: A Novel of the Next World War" by Elliot Ackerman and James Stavridis depicts a worst-case scenario of what happens when submarine cables are lost. Even for me, someone who has long argued that cables can be deliberately destroyed, this scenario seems a bit extreme...
In any case, without connected submarine cables, we would lose access to the information and communication services we enjoy today. Online classes would become impossible. This has made me appreciate them all over again.
I hope that the submarine cable connection is quickly restored for the people of Tonga and that their peaceful lives can return.
And to all the students preparing for entrance exams, I know you must be going through a very difficult time waiting for next month amidst the spread of the Omicron variant. Keio University and SFC are preparing for the entrance examinations with all possible countermeasures. I hope to see you all on campus in the spring.