Residents began rebuilding homes and businesses in Coquimbo on Friday, two days after tsunami waves triggered by a major earthquake battered the Chilean port city's waterfront neighborhoods.

Soldiers patrolled the streets to prevent looting after President Michelle Bachelet's government declared an emergency in Coquimbo following the 8.3-magnitude quake, which killed 12 people.

At least one strong aftershock shook Chile's Pacific seaboard on Friday as residents trying to salvage what they could from their properties urged the government to speed up the relief effort.

"We're just getting started with removing the mud and the rubble," said Maria Gonzalez, whose fish and seafood restaurant in Coquimbo's port was badly damaged. "They have to help us fix our businesses and get back to the life we had."

Waves of up to 4.5 meters (15 feet) slammed into Coquimbo's shoreline, flinging large fishing boats and shipping containers onto the streets and sending floodwaters pouring into downtown.

The quake was the strongest recorded in the world this year, but the swift evacuation of coastal zones and strict building regulations appeared to help keep the death toll low.

Some Coquimbo residents said government aid was slow to arrive. A handful of protesters briefly blocked the highway leading to and from the city on Friday morning before police arrived and dismantled their roadblock.

"We haven't eaten in three days!" one of the demonstrators shouted.

Luciano Robles, an official with Coquimbo's civil emergency office, said help was on the way.

"We understand that people are desperate and don't know what to do," he told Reuters around midday.

"The aid packages arrived this morning and are being distributed, starting now."

The economic cost of the earthquake, which followed floods in northern Chile and volcanic eruptions in the south earlier this year, could be anywhere between $100 million and $1 billion, Fitch rating agency said.

Bachelet, who was widely criticized for her slow response to a monster quake in 2010 that killed more than 500 people, hugged victims as she toured the disaster zone on Thursday.

Those hit by the tsunami lost practically everything, said Askaan Wohlt of the Desafio Levantemos Chile charity, which was established after the 2010 earthquake.

"Our focus is going to be to help businesses rebuild," said Wohlt.

The tsunami that hit Coquimbo flooded a warehouse for copper concentrate from the Caserones mine, Japan's JX Nippon Mining and Metals said on Friday. The company said it did not know how much copper concentrate was stored there.

Chile is the world's largest copper producer. Concerns over supply disruptions eased on Thursday when state copper miner Codelco restarted operations at its Andina project and London-listed Antofagasta Plc said it expected to resume normal operations.

The massive 8.8-magnitude quake that walloped south central Chile some five years ago released five times more energy than Wednesday's temblor, according to Juan Carlos de la Llera, dean of engineering at Chile's Universidad Catolica.