Massive: An example of a pumice rock from Chile's Puyehue-Cordon Caulle chain volcano is displayed. Local media said the smell of sulphur hung in the air and there was constant seismic activity. 'The Cordon Caulle (volcanic range) has entered an eruptive process, with an explosion resulting in a 10-kilometre-high gas column,' the state emergency office ONEMI said. As a precaution, the government said it was evacuating 3,500 people from the surrounding area. This development is the latest volcanic activity to affect the country. Three years ago, Chile's Chaiten volcano erupted spectacularly for the first time in thousands of years, spewing molten rock and a vast cloud of ash that reached the stratosphere and was visible from space. It also drifted over neighboring Argentina, coating towns. Chile's Llaima volcano, one of South America's most active, also erupted that year and again in 2009. Chile's chain of about 2,000 volcanoes is the world's second largest after [that of] Indonesia. Some 50 to 60 are on record as having erupted, and 500 are potentially active.