Chile issued a red alert on Monday for the Copahue volcano on the border with Argentina that has become increasingly active.
Chile's Interior and Security Minister Andres Chadwick said the increased activity could lead to an eruption and officials will soon begin evacuating 2,240 people, or 460 families, from their homes in a 25-kilometre radius.
"This evacuation is obligatory; it's not voluntary," Chadwick told reporters.
Chile's Emergency Office says the evacuation could last about 48 hours, but could be delayed because of heavy rains.
The nearly 2,965-metre volcano sits in the Andes cordillera, straddling the border with Argentina's Neuquen province.
Argentine officials have issued a yellow alert. They overflew the area during the weekend and are monitoring the volcano with a network of web cameras. Access to the volcano is closed within a four-kilometre radius on the Argentine side, but nearby towns, including Villa de Caviahue, are open for business.
The Copahue started spewing ash and gas in December, prompting a red alert then.
The volcano had a major eruption in 1992, according to the Mining Ministry's Sernageomin geology unit. It became highly active with blasts and gases in 2002, in its strongest activity in more than 20 years.