SYDNEY – A powerful earthquake in Chile has turned the copper market's focus back onto supply risks rather than Chinese demand, after mine operations have once again been disrupted in a country that accounts for a third of the world's supply of the metal.

With the global copper market expected to see a small surplus this year, investors had recently been paying more attention to the threat from a slowdown in economic growth in top consumer China.

These worries pushed down benchmark copper prices to a six-year low last month. But early on Thursday, prices surged to an eight-week top of $5 440.50/t on news of the 8.3 magnitude Chile earthquake that prompted two miners to suspend operations.

The quake, which killed five people and forced 1 million to flee their homes, was the biggest since 2010 to hit Chile, and threatened around 600 000 t of annual copper capacity.

"It brings potential supply disruption back into focus," said strategist Daniel Hynes of ANZ in Sydney.

"We've seen disruption after disruption for a variety of reasons which highlights the supply issues in the market that can be lost when you have concerns around macro issues and Chinese economic growth," he said.

Floods hit Chile in March and April, crimping copper output, while a power shortage in Zambia has strained production at Africa's top producer. Rigorous Indonesian regulation has also impeded shipments from Freeport's huge Grasberg mine.

Hynes estimates global copper production has already fallen short by one-million tonnes from output plans for the year.

The shortfall could widen if there are reports of major damage from the earthquake in Chile.

Chile's state copper miner Codelco halted open-pit operations at its large Andina mine and evacuated workers at its smaller Las Ventanas refining and smelting division after the quake. It tweeted that there was no damage to infrastructure or personnel.

Antofagasta said its Los Pelambres copper operations were suspended but also reported no initial evidence of damage.

BHP Billiton, majority owner and operator of the world's biggest copper mine Escondida, said its operations were unaffected, while Teck Resources said it was reviewing the impact on its Carmen de Andacollo open-pit copper mine but said there was "no obvious damage".

According to a median of analysts polled by Reuters in July, the world copper market is seen in a surplus of nearly 200 000 t this year.

But global miners such as Glencore have announced small cutbacks as some operations become uneconomical, tightening the supply pipeline and prompting cautious optimism on prices.