Peru declared a state of emergency Thursday in nine districts threatened by the Ubinas volcano, which has erupted seven times since September 1, spewing harmful gas and ash.

Authorities are distributing masks and have given themselves a 60-day period to relocate villagers from areas where ash is damaging crops and polluting water sources.

The explosions have sent a plume of smoke rising to 2,500 meters (2,734 yards) above the crater, according to volcanologists at the Geophysical Institute of Peru.

The first explosion on the night of September 1 was strong and followed by a series of lesser blasts, seismologist Victor Aguilar of the Geophysical Institute of the University of San Agustin de Arequipa told AFP.

The volcano, in the Moquegua department 1,250 kilometers (776 miles) south of Lima, is the most active in the country.

Peru's Geological, Mining and Metallurgical Institute said the eruption could have been caused by snow accumulating in the crater and preventing normal emissions.

Since 1550, 25 eruptions have been recorded at Ubinas. There are 40 volcanoes in Moquegua and the neighboring regions of Arequipa and Tacna, most of them dormant.