Four Pacific Rim volcanoes rumble to life

Four volcanoes along the Pacific Ring of Fire have either erupted or look likely to explode after emitting smoke, ash and red hot rock.

The volcanic unrest has forced hundreds of thousands of people to evacuate areas in Indonesia, Vanuatu and Mexico.

Aerial footage shot by the New Zealand Defence Force (NZDF) shows Vanuatu's Monaro Volcano rumbling to life.

"It's bubbling away quite fiercely," NZDF's tactical aerial survey co-ordinator Mark Chadwick says. "There's a lot of ash and steam and debris being ejected from the crater."

Authorities fear an eruption is imminent, and have ordered the evacuation of 10,000 people living on Ambae Island - which Mr Chadwick says is a "smart move".

"There is a lot of debris and scorched vegetation, which depending on the wind flow, could affect other parts of the island as well."

Monaro isn't the only volcano on the Pacific Ring of Fire that looks set to blow.

Mt Agung in Bali has also been rumbling, and further north Mt Sinabung on North Sumatra has been blasting ash.

Across the Pacific in Mexico, the Popocatépetl Volcano is also showing signs of unrest, spewing glowing rock and ash over the already quake-ravaged country.

More than 30,000 people have fled North Sumatra's Mt Sinabung, but the biggest impact has been on popular tourist destination Bali.

Around Mt Agung, 75,000 people have evacuated.

Smoke has been seen billowing from its peak, and thousands of volcanic tremors have been felt.

"I'm scared, really scared," one resident says. "The volcano is going to erupt."

Denpasar Airport's alert level has been raised to orange. If it reaches red, the airport will be shut down.

There are 450 New Zealanders registered as being in Bali, 127 in Vanuatu and 120 in Mexico.

People are warned to stay away from volcanic areas.