Two million people have been affected by the massive earthquake that struck central Chile on Saturday, President Michelle Bachelet has said.
In a TV address, she said the forces of nature were testing the nation.
So far at least 300 people have been confirmed killed in the earthquake that struck in the early hours of Saturday.
The 8.8 quake - one of the biggest ever - triggered a tsunami that has been sweeping across the Pacific, although waves were not as high as predicted.
Japan is still on high alert, with scores of thousands of people urged to evacuated areas at risk.
Tourists stranded
Ms Bachelet said the forces of nature had "once again put to the test our ability to deal with adversity and get back on our feet. And we are examining every way to restore all the basic services in the country. But there's still a lot to do".
AT THE SCENE
Gideon Long, BBC News, Santiago
The streets of the capital, usually buzzing with activity on a summer weekend like this, are eerily quiet and dark. Nearly 24 hours after the quake struck, whole swathes of the city have no electricity and no running water.
Many people have packed up and left to stay with friends and relatives who are better off than they are.
The city's new buildings seemed to have survived more or less intact. But it's the old buildings that suffered. I drove past my local church - still intact but missing its dome, which crashed to the ground when the earth began to shake.
Around the city of Concepcion, whole villages have been flattened. Highways have been sliced in two and bridges have collapsed.
But help is arriving. Chile has a long history of earthquakes and the authorities here know how to deal with them.
Ms Bachelet said she had declared a state of catastrophe in six regions.
Chile is vulnerable to earthquakes, being situated on the Pacific "Ring of Fire" where the Pacific and South American plates meet.
The earthquake struck at 0634 GMT, 115km (70 miles) north-east of the city of Concepcion and 325km south-west of the capital Santiago at a depth of about 35km. It is the biggest to hit Chile in 50 years.
Widespread damage to roads and buildings has been reported in many areas, including the capital where a chemical plant caught fire.
Electricity, water and phone lines have been cut.
At least 85 people died in the region of Maule alone, journalists there reported.
Many deaths were also reported in the regions of Santiago, O'Higgins, Biobio, Araucania and Valparaiso.
TV pictures showed a major bridge at Concepcion had collapsed into the Biobio river.
Rescue teams have been searching the wreckage of toppled buildings for survivors.
In Santiago, where at least 13 people were killed, several buildings collapsed - including a car park.
A fire at a chemical plant in the outskirts of the capital forced the evacuation of the neighbourhood.
More than 200 prisoners escaped from a jail in the town of Chillan.
About 60 have been recaptured so far and the 600 inmates in custody have been transferred to a facility in Concepcion.
The BBC's Candace Piette, who travelled to Santiago by road from the Argentina border, says the drive from the Andes was difficult, with many damaged roads.
In the capital the effects are patchy, she says, with many parts still blacked out and some water services cut.
Tourists are stranded in hotels unable to leave because of the international airport's closure and some people have been bedding down in city squares, scared to sleep inside.
The US Geological Survey (USGS) has recorded numerous aftershocks, the largest of 6.9 magnitude.
The airport terminal in Santiago was damaged and will be closed for at least 72 hours, officials said. Flights are being diverted to Mendoza in Argentina.
POWERFUL EARTHQUAKES
Haiti, 12 Jan 2010: About 230,000 people die after shallow 7.0 magnitude quake
Sumatra, Indonesia, 26 Dec 2004: 9.2 magnitude. Triggers Asian tsunami that kills nearly 250,000 people
Alaska, US, 28 March 1964: 9.2 magnitude; 128 people killed. Anchorage badly damaged
Chile, south of Concepcion, 22 May 1960: 9.5 magnitude. About 1,655 deaths. Tsunami hits Hawaii and Japan
A tsunami triggered by the earthquake struck the Juan Fernandez island group off the Chilean coast and local media say five people died there with several others missing.
As the tsunami radiated across the Pacific, Japan warned that a wave of 3m (10ft) or higher could hit the Pacific coast of its island of Honshu.
The BBC's Roland Buerk in Tokyo says the waves so far have been small but officials say worse could still be to come.
The biggest wave so far has been just over one metre.
Steel gates have been erected at some ports and coastal railways have been closed. About 140 people died in Japan from a tsunami after the earthquake in Chile in 1960.
In French Polynesia, waves 6ft (1.8m) high swept ashore, but there were no immediate reports of damage.
In Tonga, hundreds of people sheltered in the grounds of the king's hillside mansion.
Hawaii later lifted its tsunami warning after waves measuring just under 1m (3ft) high struck but caused no damage.
In Washington, President Barack Obama said the US was ready to help if the Chilean government required it.
Chile suffered the biggest earthquake of the 20th century when a 9.5 magnitude quake struck the city of Valdivia in 1960, killing 1,655 people.
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