Nations around the Pacific Ocean are on full alert as a tsunami triggered by a 8.8 magnitude earthquake in central Chile brings higher than normal waves.
Tsunami warnings have been sounded in an area affecting about a quarter of the globe.
Waves have spread from the epicentre of quake and may strike land bordering the Pacific in the next 24 hours.
Warning systems have improved since the 2004 Indonesia quake sparked a tsunami that killed some 250,000 people.
Nations affected by the Pacific “Rim of Fire” have all sounded alerts, trying to estimate the anticipated time of arrival of any tsunami.
The Pacific Tsunami Warning Center has said there may be “widespread damage” from high waves.
A warning was issued in Hawaii for a possible tsunami
“Authorities should take appropriate action in response to this threat,” it said.
Large waves are reported to have struck Chile’s Juan Fernandez island group, reaching halfway into one inhabited area. Three people there are missing, local media say. Two aid ships are reported to be on their way.
Parts of French Polynesia’s coast were hit by waves of up to 6ft (2m) at 1630 GMT, but there was no damage immediately reported.
It has been difficult to estimate the possible wave heights of any tsunami – the waves may not arrive at all or could be as high as 10 metres above normal sea level.
In Tahiti, traffic was banned on roads less than 500m from sea, and residents on low-lying land were told to get to higher ground, but the first tsunami waves were smaller there, measuring only 36cm.
New Zealand has warned waves up to 3m could hit the main North and South Islands plus outlying islands.
The Pacific Tsunami Warning Center in Hawaii was monitoring the waves
Waves measuring 20cm hit the Chatham Islands, about 400 miles from the mainland, about 1905 GMT, but the Ministry of Civil Defence warned that “the greatest wave heights will occur between six and 12 hours after the initial arrivals.”
American Samoa has urged residents to seek shelter, calling on coastal villagers to seek higher ground.
Sirens were sounded in Hawaii to alert residents to the tsunami threat several hours before waves were expected.
The first waves in Hawaii are expected about 1100 local time on Saturday (2100 GMT) and measure about 8ft (2.5m).
John Cummings, Oahu civil defence spokesman, said: “Get off the shoreline. We are closing all the beaches and telling people to drive out of the area.”
Australian officials warned of “possible dangerous waves, strong ocean currents and foreshore flooding” from Sydney to Brisbane.
Japan may be hit at 0300 GMT on Sunday, the country’s meteorological agency said, calling for people to be fully alert.
California has also warned its coastal cities to prepare for possible tsunami waves, the first strike possibly around San Diego.
The Cook Islands, Kiribati, Niue, Tonga, the Solomon Islands, Fiji and Vanuatu could also all be at risk.