Tonga’s vital subsea cable may take weeks to repair after volcanic eruption

20 Jan 2022

Image: © mdurinik/

A massive volcanic eruption caused damage to the 827km long subsea cable between Tonga and Fiji.

The island nation of Tonga’s internet blackout will likely continue for weeks after a volcanic eruption damaged its sole subsea communications cable.

Tonga was cut off from the outside world following the explosion of the underwater Hunga Tonga-Hunga Ha’apai volcano last weekend, which knocked out communications, killed at least three people and sent tsunami waves across the Pacific.

The massive eruption was heard as far away as Alaska and, despite being underwater, the eruption was strong enough to be visible from space.

The underwater eruption caused damage to the 827km long subsea cable between Tonga and Fiji, the nation’s main source of internet connection. The cable owner, Tonga Cable Ltd, said the damage is about 37km offshore.

“Communications both international and domestic were severed due to damage sustained by the submarine cable from the eruptions,” the government of Tonga said in its first official update on Tuesday (18 January).

“Due to the damage to the international fibre optic cable, the internet is down.”

While telephone links have been restored between Tonga and the rest of the world, restoring internet connectivity is expected to take far longer.

“US cable company SubCom advises it will take at least four weeks for Tonga’s cable connection to be repaired,” New Zealand’s foreign ministry said on Wednesday (19 January).

A specialist ship plans to embark on a repair mission to fix the undersea cable. But the unknown scale of cable damage, along with a journey to the dangerous fault area, means repair times could take longer than a month.

“The cables are actually around the volcanic zone. We don’t know … whether they are intact or blown away or stuck somewhere underwater. We don’t know if it’s buried even deeper,” Samiuela Fonua, chair of Tonga Cable, told Reuters.

The communications blackout in Tonga made relief efforts more difficult, highlighting the vulnerability of subsea fibre-optic cables that have become a vital network for data travelling around the globe. Without the cable, countries were relying on satellite phone connections, surveillance flights and satellite images to measure the full scale of the disaster.

In 2011, the World Bank Group and the Asian Development Bank announced that they would fund a new submarine cable to Tonga. The $34m cable was completed in 2018 and greatly boosted Tonga’s internet connectivity, but it is the nation’s primary connection to the outside world.

According to internet observation company Kentik, connecting remote island nations with high-speed access is a great challenge. Without a subsea cable, these locations are reliant on expensive satellite services that suffer from latency and capacity issues. But these locations are also small for investment returns, meaning private investors usually avoid them.

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Leigh Mc Gowran is a journalist with Silicon Republic