Five people were crushed to death or suffered fatal heart attacks, a remarkably low toll for such a powerful shift in the Earth’s crust.
The extent of damage has not yet been fully assessed, President Michelle Bachelet said, but she sent a military plane with 100 anti-riot police to join 300 soldiers deployed to prevent looting and round-up escaped prisoners.
The shaking caused landslides that blocked roads, knocked out power for thousands, damaged an airport and provoked fires that destroyed several businesses.
About 300 inmates escaped from a women’s prison in the city of Iquique.
Around 40 of the women were soon recaptured after Chile’s military sent a planeload of special forces to the area, the country’s investigative police said.
In Arica, another city close to the quake’s offshore epicentre, hospitals treated minor injuries, and some homes made of adobe were destroyed, authorities said.
Interior minister Rodrigo Penailillo announced the five deaths.
Ms Bachelet’s government extended its tsunami warnings for northern-most Chile long after they were lifted elsewhere.
Its mandatory evacuation orders remained in effect until nearly dawn for coastal areas north of Antofogasta, a decision backed by the Pacific Tsunami Warning Centre in Hawaii.
Geophysicist Gerard Fryer said: ‘We regard the coast line of Chile as still dangerous, so we’re maintaining the warning.’
Ms Bachelet, who just returned to the presidency three weeks ago, spoke well after midnight, five hours after the quake struck at 8.46pm local time yesterday (00.46am BST today).
It was not lost on many Chileans that the last time she presided over a major quake, days before the end of her 2006-10 term, her emergency preparedness office prematurely waved off a tsunami danger.
Most of the 500 dead from that magnitude-8.8 tremor survived the shaking, only to be caught in killer waves in a disaster that destroyed 220,000 homes and washed away large parts of many coastal communities.
‘The country has done a good job of confronting the emergency. I call on everyone to stay calm and follow the authorities’ instructions,’ she tweeted after the latest quake.
When she finally addressed the nation, she said Mr Penailillo would monitor the tsunami threat throughout the night and co-ordinate the emergency response.