The 15 January eruption and tsunami caused wide destruction, killing three people and damaging hundreds of homes.

In the immediate aftermath, the country was cut off from global reach because the underwater cable had been severed.
https://www.bbc.com/news/world-asia-60458303

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Communications restored to Tonga a month after volcanic eruption and Tsunami

Tonga has been reconnected to the world following repairs to a submarine cable, a month after a volcanic eruption and tsunami cut communications to the remote Pacific island nation.

“People on the main island will have access almost immediately,” the Tonga Cable chief executive, James Panuve, told Reuters by telephone, after a repair ship handed over the restored cable on Tuesday afternoon.
https://www.theguardian.com/world/2022/feb/22/communications-restored-to-tonga-a-month-after-volcanic-eruption-and-tsunami

Tonga’s internet finally restored 5 weeks after big eruption

Tonga’s main internet connection to the rest of the world has finally been restored more than five weeks after a huge volcanic eruption and tsunami severed a crucial undersea cable.

Three people in Tonga were killed by the Jan. 15 tsunami, dozens of homes were destroyed and drinking water was tainted.

The fiber-optic cable is now fully operational again after being reconnected Tuesday, said Samiuela Fonua, the chairperson at Tonga Cable Ltd., the state-owned company that owns the cable.
https://apnews.com/article/spacex-coronavirus-pandemic-technology-business-health-104298b3b7f4fd4773d1021b26302cb6

Internet restored to Tonga after cable destroyed by eruption is repaired

An internet cable damaged during Tongan’s Hunga Tonga-Hunga Ha’apai volcanic eruption and resulting tsunami, has finally been repaired.
https://www.stuff.co.nz/world/south-pacific/300523665/internet-restored-to-tonga-after-cable-destroyed-by-eruption-is-repaired