Chilean volcano Calbuco has erupted for the third time in eight days, sending a new cloud of ash and gas high into the sky.

Officials said the latest eruption, which sent ash 4km into the sky, was less powerful than those last week. Calbuco erupted for the first time in more than 50 years on the evening of April 22 - and then subsequently erupted again several hours later.

The volcano spewed more than 200 million tonnes of ash last week, coating nearby towns, wrecking parts of the salmon industry and forcing the cancellation of flights as far as Buenos Aires 1,400km away.

Calbuco has been quiet this week, but geological officials had warned it was still unstable and could erupt again

Aerial footage of Chile's Calbuco volcano spewing ash

Officials set up a 20km evacuation radius around the volcano following the latest eruption.

President Michelle Bachelet, speaking in Arica city in the country's north, said 6,514 people had been evacuated and that the government would continue to do all it could to keep residents safe.

Lower ash cloud

Chile's Deputy Interior Minister Mahmud Aleuy said the ash from the latest eruption was likely to affect areas south of the volcano.

"The seismic intensity of this eruption is much lower than that of the two others, particularly the first. The ash cloud reached no more than 4km in height. You will remember that the first reached 17km," Aleuy said.

Officials warned, however, that heavy rain or snow on Friday could lead to complications such as lahares - destructive flows of debris that can wipe out anything in their path.

"This emission should begin to weaken in the coming hours...but we are in an eruptive process, on red alert, and the situation can change at any time," said Sernageomin head Rodrigo Alvarez.

Calbuco, one of the most active along a chain of around 2,000 in Chile, is in the scenic southern Los Lagos region, a popular tourist destination around 1,000km south of the capital, Santiago.

Source: Al Jazeera and agencies