Chile's Interior Minister Rodrigo Penailillo attributed the five deaths to heart attacks or being crushed. The quake forced evacuations along the country's entire Pacific coast for fear of tsunamis.Thousands have lost power, and hundreds of thousands of Chileans are spending the night away from their beds due to the evacuation order, which remains in effect for northern Chile.
The US Geological Survey initially reported the quake at 8.0, but later upgraded the magnitude. It said the quake struck 99 kilometers (61 miles) northwest of the Chilean city of Iquique at 8:46 p.m., hitting a region that has been rocked by numerous quakes over the past two weeks.
The quake was so strong that the shaking experienced in Bolivia's capital about 470 kilometers (290 miles) away was the equivalent of a 4.5-magnitude tremor, authorities there said.
At least eight 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.
Some roads in northern Chile were blocked by landslides, causing traffic jams among people leaving the coast.
Coastal residents of northern Chile evacuated calmly as waves measuring almost 2 meters struck their cities ahead of a tsunami that was expected to come ashore later.
Chile is the world's No. 1 copper producer but key mining firms said there was no serious damage to their operations. The tsunami alert in the country would however go on for at least another six hours, the government said late on Tuesday.
State-owned miner Codelco reported no harm to its workers or mines, and said its operations in northern Chile were normal.
Chile's Collahuasi copper mine and port had no immediate problems following the quake, chief executive Jorge Gomez told Reuters, and mining company BHP Billiton said it had not received reports of damage.
In 2010, an 8.8-magnitude quake triggered a tsunami that devastated several coastal towns in central-south Chile, a disaster that killed 526 people. Chile's ONEMI emergency office said late Tuesday that landslides were partially blocking some roads and highways.
"An earthquake of this size has the potential to generate a destructive tsunami that can strike coastlines near the epicenter within minutes and more distant coastlines within hours," the Pacific Tsunami Warning Center said.
"An evaluation of the Pacific wide tsunami threat is underway and there is a possibility that Hawaii could be elevated to a watch or warning status," it added.Authorities in the US state of Hawaii were on alert, but no tsunami watch was issued. The tsunami center said any higher waves would hit Hawaii starting 3:24 a.m. Hawaii Standard Time.
Authorities in Peru started evacuating communities in the southern coastal region of Ica. Electricity was partially lost in the Peruvian cities of Tacna, Moquegua and Arequipa but there were no reports of deaths or serious damage there.
The unnerving activity began with a strong magnitude-6.7 quake on March 16 that caused more than 100,000 people to briefly evacuate low-lying areas, although no tsunami materialized and there was little physical damage from the shaking.
The strongest earthquake ever recorded on Earth also happened in Chile - a magnitude-9.5 tremor in 1960 that killed more than 5,000 people.