Volcanic activity at Mount Ruapehu is increasing and an eruption could occur at any time, scientists warned on Tuesday. The volcano, famed as a location in The Lord of the Rings film trilogy, last erupted on September 25 2007, spitting two metre boulders distances of up to two kilometres. Ruapehu’s elevated alert level has not been changed, but scientists said on Tuesday that activity within the mountain was greater, with high levels of gas spewing out, a warmer than average crater lake and ongoing volcanic tremors. “The volcano remains in a status of unrest and the possibility of further activity remains. If further eruptions occur, they may occur without warning,” Geological and Nuclear Sciences (GNS) said in a statement.