Copper futures gained the most in nearly a year, before declining on reports that the earthquake in Chile has not caused major disruptions to supply.

Chile’s mines, which are situated mostly in the northern part of the country, remain relatively unaffected, except for some power outages.

The Chilean quake cut power and briefly disrupted production at mines run by state-owned Codelco.

As miners confirmed that operations were resuming, copper futures for May delivery, paring an earlier gain of more than 6%, added seven cents or 2.1% to end at $3.35 a pound on the New York Exchange.

Anglo American said that power has been partially restored at four sites impacted by the quake while Freeport’s Candelaria mine had been temporarily offline and Antofagasta’s Los Pelambres mine had also resumed production.

The rise in copper comes after February’s 7.1% rise, the strongest monthly gain for the active copper contract since August 2009.

Chile produces one-third of the world’s supply of copper.