A TSUNAMI has slammed California with huge 4ft waves amid evacuation alerts in the US, Japan and Australia after a massive underwater volcano erupted off the coast of Tonga.
It comes as waves of 2.7ft swept through the streets of the Pacific nation as locals scrambled to higher ground after the "violent" eruption of the Hunga Tonga-Hunga Ha'apai volcano.
The eruption was so intense it was heard as "loud thunder sounds" in Fiji more than 500 miles away, officials said.
Now other countries have issued alerts to protect their citizens.
Japan's meteorological agency issued tsunami warnings in the early hours on Sunday and said waves as high as three metres were expected in the Amami islands in the south.
In a briefing, a Japan Meteorological Agency official urged people not to go near the sea until the tsunami advisory and more serious tsunami warnings had been lifted.
Meanwhile, Californian cities including Santa Monica and Santa Cruz have been hit by flooding as a result of the tsunami with many beaches shut.
Waves of up to 4.1 feet have been recorded in Port San Luis according to the National Weather Service as locals rushed to watch on in awe as defiant surfers took to the treacherous waters.
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The agency has warned people to stay away from the shore and head to high ground.
A notice said: "Tsunami surging has been reported at all coastal locations.
"If you are located in this coastal area, move off the beach and out of harbors and marinas.
"Do not go to the coast to watch the tsunami.
Dave Snider, Tsunami Warning Coordinator at the National Tsunami Warning Center in Palmer, , told : "We have seen the wave moving through Hawaiian Island."
Snider added: "We don't have a really good forecast because this event is based on a rather than earthquake."
Berkeley Fire Department have ordered a mandatory evacuation for people living in the Marina or the surrounding area.
And more than 1,400 miles away in New Zealand, officials warned 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 the large volcanic eruption.
Authorities in the nearby nations of Fiji and Samoa also issued urgent warnings, telling people to avoid the shoreline due to strong currents and dangerous waves.
Similar warnings were issued by authorities in Australia - where officials said a swathe of coastline including Sydney could be hit by tsunami waves.
People in New South Wales were "advised to get out of the water and move away from the immediate water's edge".
There were no immediate reports of injuries or the extent of the damage after the island of 105,000 people was plunged into darkness from the volcanic explosion.
Footage posted on social media showed large waves crashing ashore in coastal areas, swirling around homes and buildings.
GAS, ASH AND SMOKE
New Zealand's military said it was monitoring the situation and remained on standby and ready to assist the nation.
Horrifying satellite images from space showed the huge eruption, which lasted at least eight minutes and sent plumes of gas, ash and smoke several miles into the air.
The Tonga Meteorological Services said a tsunami warning was in effect for all of Tonga as the island's capital lies just 65km north of the volcano.
The head of Tonga Geological Services, Taaniela Kula, urged people to stay indoors, wear a mask outside and cover rainwater reservoirs in case of acid rain.
The explosion of the volcano was the latest in a series of spectacular eruptions.
One Twitter user posted a video showing waves hitting the shoreline.
He said: "Can literally hear the volcano eruption, sounds pretty violent. Raining ash and tiny pebbles, darkness blanketing the sky."
Tongan resident Mere Taufa said the eruption hit as her family was preparing for dinner - and her younger brother thought bombs were exploding nearby.
TONGA KING EVACUATED
She told New Zealand news site Stuff.co.nz: "My first instinct was to take cover under the table, I grabbed my little sister, and screamed at my parents and others in the house to do the same."
Taufa said the next thing she knew, water was rushing into their home.
"You could just hear screams everywhere, people screaming for safety, for everyone to get to higher ground," she said.
Tonga's King Tupou VI was reported to have been evacuated from the Royal Palace in Nuku'alofa and taken by a police convoy to a villa away from the coastline.
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The Matangi Tonga news site said scientists had seen massive explosions, thunder and lightning near the volcano after it started erupting early on Friday.
The site said satellite images showed a three-mile wide plume of ash, steam and gas rising up 12 miles into the air.