The volcano, about 37 miles west of Alto Biobio, spewed a large cloud of ash and smoke Saturday, prompting provincial emergency officials to issue a yellow alert. Chile's Geological and Mining Service raised the alert to red Sunday because it could not rule out a major eruption, CNN reported Monday.
The agency warned about potentially dangerous mudslides within a 9.3-mile radius of the crater.
Copahue volcano formed about 500,000 years ago as a string of nine craters along this stretch of the Andes Mountains, CNN reported. It's been more than a decade since the volcano's last eruption.