Tsunami warnings are in place following the eruption which was seen clearly from space, reports ITV News' Mark McQuillan
People in Japan and parts of the US have been told to keep away from the shore amid tsunami warnings sparked by a huge underwater volcanic eruption near the island of Tonga.
The underwater Hunga Tonga Hunga Ha’apai volcano eruption on Saturday was so powerful it was seen from space by satellites orbiting the earth, showing a plume of ash, steam and gas rising like a mushroom above the blue Pacific waters.
Tsunami warnings were issued for the west coast of the US, Chile, the Canadian Pacific coast, as well as parts of Japan and Australia.
The eruption has been described as "one of the most violent" to ever be captured from space.
It sent tsunami waves crashing ashore on Tonga, washing through buildings, homes and a church, forcing people to escape to higher ground, while the eruption generated powerful sonic booms heard 500 miles away in Fiji.
There were no immediate reports of injuries or the extent of the damage as most contact with Tonga was lost at about 6.40 pm local time (5.40am GMT), said Doug Madory, director of internet analysis for the network intelligence firm Kentik.
Mary Fonua, a Tongan journalist, did manage to make contact and said she was okay but was worried about others living in low-lying areas nearby.
"There's thousands of people up in that area on a narrow peninsula so I'm very concerned for those people just up the road from us here," she said.
New Zealand's military said it was monitoring the situation and remained on standby, ready to assist if asked.
A convoy of police and military troops evacuated Tonga's King Tupou VI from his palace near the shore.
Dr Boris Behncke, a volcanologist, told ITV News: "[The eruption] also caused a shockwave, which is an atmospheric pressure wave which was visible in the satellite footage. So that is something that we do not see every day.
"That seems like it's a really large event - possibly one of the larger explosive eruptions of the century".
A Twitter user identified as Dr. Faka’iloatonga Taumoefolau posted video showing waves crashing ashore.
“Can literally hear the volcano eruption, sounds pretty violent,” he wrote, adding in a later post: “Raining ash and tiny pebbles, darkness blanketing the sky.”
The Tonga Meteorological Services said a tsunami warning was in effect for all of Tonga. Authorities in the nearby island nations of Fiji and Samoa also issued warnings, telling people to avoid the shoreline due to strong currents and dangerous waves.
More than 1,400 miles away in New Zealand, officials were warning of storm surges from the eruption.
The National Emergency Management Agency said some parts of New Zealand could expect “strong and unusual currents and unpredictable surges at the shore following a large volcanic eruption.”
Residents along the US Pacific coast were also advised to move away from the coastline to higher ground and to pay attention to specific instructions from their local emergency management officials, said Dave Snider, tsunami warning coordinator for the National Tsunami Warning Center in Palmer, Alaska.
“We don’t issue an advisory for this length of coastline as we’ve done - I’m not sure when the last time was - but it really isn’t an everyday experience,” Mr Snider said.
Beaches and piers were closed across Southern California as a precaution.
The first waves to hit the continental US measured about 1 foot in Nikolski, Alaska and 1.9 feet in Adak, Alaska. A wave of about 2.6 feet was observed in Monterey, California, according to the US National Tsunami Warning Center.
The National Weather Service tweeted there were “no significant concerns about inundation.” Strong rip currents were possible, however, and officials warned people to stay out of the water.
In Hawaii, the Pacific Tsunami Warning Center reported waves as high as 1.6 feet in Nawiliwili, Kauai and 2.7 feet in Hanalei and residents were urged to stay away from the coast.
The National Weather Service said there were reports of boats getting pushed up in docks, but the hazard diminished as the morning went on with only minor flooding.
The explosion of the Hunga Tonga Hunga Ha’apai volcano was the latest in a series of spectacular eruptions.
Earlier, the Matangi Tonga news site reported that scientists observed massive explosions, thunder and lightning near the volcano after it started erupting early Friday.
The site said satellite images showed a 5-kilometer (3 mile) -wide plume of ash, steam and gas rising up into the air to about 20 kilometers (12 miles).
The volcano is located about 64 kilometers (40 miles) north of the capital, Nuku’alofa. Back in late 2014 and early 2015, a series of eruptions in the area created a small new island and disrupted international air travel to the Pacific archipelago for several days.
Tonga is home to about 105,000 people.