Copper prices fell on Thursday, a day after reaching their highest levels in two months, as mining companies resumed production following an earthquake in the Chile, the world's top copper producer.

Copper dropped as much as 6.4 percent following BHP Billiton's announcement on Thursday that it was resuming operations at its copper mines in the region. Meanwhile Chile's Codelco said operations were fully restored a day after the quake cut off power to its mines at its largest division, Codelco Norte.

Chile was hit by a second earthquake today, with a magnitude of 6.8, the U.S. Geological Survey said.

Chile's mineral-rich Antofagasta region was hit by a massive 7.7 magnitude earthquake on Wednesday. This ignited a pause in productions at some of the world's largest copper mines. Chile provides more than a third of the world's annual supply of copper.

Overall copper stocks are still at historically low levels,'' RBC Capital Markets traders led by Alex Heath said in a report. The overall price pattern appears distinctly bullish to us in the medium term.

China, the world's largest copper consumer, produced a record 358,000 tons of the metal last month, according to government data released today. Output gained 15 percent from September, and 44 percent from a year ago.

Copper futures were down 21.30 cents, or 46.38 percent, at $312.350 a lb by 12:58 a.m. EST on the New York Mercantile Exchange's COMEX division.

Copper Earthquake