Five people were crushed to death or suffered fatal heart attacks, the interior minister said, but Chile apparently escaped major damage or serious casualties in the quake that struck last night.
The shaking loosed landslides that blocked roads, power failed for thousands, an airport was damaged and several businesses caught fire. About 300 inmates escaped from a women's prison in the city of Iquique, and Chile's military was sending a planeload of special forces to help police guard against looting.
In the city of Arica, 139 kilometres from the quake's epicenter, hospitals were treating minor injuries, and some homes made of adobe were destroyed and 90 per cent of customers were without power, authorities said.
An elderly person is evacuated from a shelter after a major earthquake of magnitude 8.2 struck off the coast of Chile. (Reuters)
The quake also shook modern buildings in nearby Peru and in Bolivia's high altitude capital of La Paz.
Hours later, a tsunami warning remained in effect for northern Chile, but alerts were lifted elsewhere.
"We regard the coast line of Chile as still dangerous, so we're maintaining the warning," geophysicist Gerard Fryer at the Pacific Tsunami Warning Centre told The Associated Press.
Chile's Emergency Office said its tsunami watch would remain in effect for six more hours, meaning hundreds of thousands of people along the coast would not sleep in their beds. Swimmers and surfers in the US state of Hawaii, thousands of miles away in the Pacific, might see higher waves today, the warning centre said.
The US Geological Survey initially reported the quake at 8.0, but later upgraded the magnitude. It said the quake struck 99 kilometres northwest of Iquique, hitting a region that has been rocked by numerous quakes over the past two weeks.
Psychiatrist Ricardo Yevenes said he was with a patient in Arica when the quake hit. "It quickly began to move the entire office, things were falling," he told local television. "Almost the whole city is in darkness."
The quake was so strong that the shaking experienced in Bolivia's capital about 470 kilometres away was the equivalent of a 4.5-magnitude tremor, authorities there said.
More than 10 strong aftershocks followed in the first few hours, including a 6.2 tremor. More aftershocks and even a larger quake could not be ruled out, said seismologist Mario Pardo at the University of Chile.