A British couple have reconnected more than 100 families with their loved ones on a Tongan island after the eruption of an undersea volcano and tsunami cut a vital communications cable.

Kate Walker, 44, and Joe Caesar, 41, lived on the island of Vava’u for eight years after moving there in 2012 and have been the only point of contact to the outside world for the entirety of its population, passing hundreds of messages on to those fearing for the safety of their friends and family.

Ms Walker, who is now based in Mangawhai in the North Island of New Zealand and works as an environmental specialist, said the operation has been “exhausting and stressful” – using a 160-character satellite device to inform the island of the extent of the crisis.

“Twelve hours after the eruption happened, Vava’u lost vital communications instantly,” Ms Walker, who grew up in Bridgend, South Wales, told the PA news agency.

“We’ve been messaging constantly to get information to people because they had no idea what happened, they initially thought it was a propane storage farm that exploded.

“They still have no idea of the scale because we can only communicate through 160-character text messages… in terms of the global scale and the importance of the eruption, they don’t know yet.

“It’s going to be a bit overwhelming for them, I think, when they do get online.”

Ms Walker and Mr Caesar, who is originally from Cambridge, moved to the island in 2012 and founded The Boatyard with their business partner, Alan Morey, setting up Tonga’s first and only yacht haulage facility.

The pair have continued to keep The Boatyard in operation despite moving to New Zealand with their five-year-old daughter, Evie, when the pandemic closed the world’s borders.

Since the eruption sent large waves crashing across the Pacific on Saturday, the couple have relied on team member Tom Marchand, who has been in possession of one of Vava’u’s only working satellite devices, a Garmin inReach.

“It’s like a tiny little Nokia 5110 – if you want the letter ‘C’ you have to press it three times,” Ms Walker explained.

Ms Walker said she and Mr Caesar have been informing families from all over the world of good news as people from Mexico, Nepal, the US, Fiji, China and Singapore have got in touch.

“We’ve been the only communications link between Vava’u and the rest of the world… I’ve lost count of the families – over 100 I reckon,” Ms Walker said.

“It’s been a full-time job for both of us for three days – something we’re very, very glad to do… we’ve just been able to constantly reassure people that everybody and everything is fine.

“It’s 15,000 people on the island and just one open channel of communication, 160 characters at a time, it’s a challenge.”

Ms Walker described the “really rewarding” moment she was able to reconnect a family friend with her husband and children.

“She’s gone overseas to earn money and he stayed (in Tonga) with three kids, and she’s been just desperate for information,” Ms Walker said.

“We were able to find her husband and bring him to The Boatyard where Tom was and (the husband) got in touch with his wife, they had a quick text… hearing from her family directly and knowing that her kids were safe has been really rewarding.”

A mother in Mexico, looking for news of her daughter, was also helped by the British couple.

“It took her a few days to find the information we were posting (on Facebook) so she’d been in quite a state for a few days, and we were very quickly able to provide her with the information that her daughter is safe, well, and fed,” Ms Walker said.

“That’s been massively rewarding, being able to provide good news when there’s so much bad news.”

Ms Walker added that she hopes pressure will start to ease as the island takes important steps forward in its bid to get connected.

On Wednesday morning, the service provider Digicel announced that international calls have been restored to Tonga.

“It’s been intense… and it doesn’t really matter that you’re tired or it’s exhausting – it’s nothing compared to what’s actually going on there,” Ms Walker added.

“And it’s nothing compared to that worry that some people have, so it’s a very small service that we can do.”