Pita Taufatofua, the Tongan Olympian who rose to fame for his entrances during the 2016 Rio Opening Ceremony, says he has not heard from his father after a tsunami hit the island nation following the eruption of an underwater volcano.

The tsunami threat around the Pacific has begun to recede while the extent of damage to Tonga remains unclear.

Satellite images showed the spectacular eruption of the Hunga Tonga-Hunga Ha'apai volcano, which happened on Saturday evening local time, with a plume of ash, steam and gas rising like a mushroom above the blue Pacific waters.

A sonic boom could be heard as far away as Alaska.

In Tonga, it sent tsunami waves crashing across the shore and people rushing to higher ground.

Mr Taufatofua posted on social media on Sunday afternoon that he had not been able to contact his father, or family who live by the water's edge.

The Olympian has started an online fundraising campaign, saying he must focus what is in his control.

"I have not yet heard from or about my father in Veitongo or family who are in Haapai," he wrote.

"For now my focus is on what I can do from my current position and that is awareness and assistance."

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The eruption cut the internet connection to Tonga, leaving friends and family members around the world anxiously trying to get in touch to figure out if there were any injuries and the extent of the damage.

Even government websites and other official sources remained without updates on Sunday afternoon.

Volcano could erupt again

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Shane Cronin, Professor of Earth Sciences at the University of Auckland, spent six nights camped out on the Hunga Tonga-Hunga Ha'apai volcano after its last series of eruptions in 2015.

As part of a team of experts, Dr Cronin ran tests across the area to study the volcanic behaviour taking place below the ocean surface and determine the likelihood of future eruptions.

ABC/Wires