An undersea volcano erupted in spectacular fashion near the Pacific nation of Tonga on Saturday, sending large tsunami waves crashing across the shore and people rushing to higher ground. A tsunami advisory was in effect for Hawaii, Alaska and the US Pacific coast, with reports of waves pushing boats up in the docks in Hawaii.

There were no immediate reports of injuries or the extent of the damage because all Internet connectivity with Tonga was lost at about 6:40pm local time — about 10 minutes after problems began, said Doug Madory, director of Internet analysis for the network intelligence firm Kentik.

Tonga gets its internet via an undersea cable from Suva, Fiji, which presumably was damaged.

The company that manages that connection, Southern Cross Cable Network, could not immediately be reached for comment

In Hawaii, the Pacific Tsunami Warning Centre reported waves slamming ashore from half a metre in Nawiliwili, Kauai, to 80cm in Hanalei.

“We are relieved that there is no reported damage and only minor flooding throughout the islands,” the centre said, describing the situation in Hawaii.

On Tonga, home to about 105,000 people, video posted to social media showed large waves washing ashore in coastal areas, swirling around homes and buildings, including a church.

Satellite images showed a huge eruption, a plume of ash, steam and gas rising like a mushroom above the blue Pacific waters.

New Zealand’s military said it was monitoring the situation and remained on standby, ready to assist if asked.

The Tonga Meteorological Services said a tsunami warning was declared for all of the archipelago, and data from the Pacific tsunami centre showed waves of 80cm had been detected.

The explosion of the Hunga Tonga Hunga Ha’apai volcano was the latest in a series of spectacular eruptions.