A volcano that doubled as Mount Doom in The Lord of the Rings series of movies is in danger of erupting as pressure builds in an underground vent, officials in New Zealand said yesterday.
The Department of Conservation warned hikers to avoid walking near the summit of Mount Ruapehu.
It said temperature readings by scientists indicated an increased risk of eruption at the country's largest active volcano.
"The current situation can't continue. Ruapehu is so active that the temperatures have been going up and down a lot," the department's volcanic risk manager Harry Keys told Radio New Zealand. "They generally haven't gone up as we've expected for some weeks now, and sooner or later that situation will be rectified, either in a small, relatively passive way or with a significant eruption."
Official monitoring body GNS Science said the temperature a few hundred metres below a lake in the crater of the North Island mountain was estimated at 800 degrees Celsius, while at the lake itself it was just 20 degrees.
It said the finding indicated a vent was partially blocked, leading to increased pressure that would make eruptions more likely "over the next weeks to months".
The 2,797 metre high volcano last erupted in 2007, sending a lahar - a fast-moving stream of mud and debris - down the side of the mountain but causing no injuries.
In 1953, a massive lahar from the volcano caused New Zealand's worst rail disaster when it washed away a bridge at Tangiwai. A passenger train plunged into the Whangaehu River, causing 151 deaths.
Filmmaker Peter Jackson used Mount Ruapehu and the neighbouring Mount Ngauruhoe to depict Mount Doom in The Lord of the Rings trilogy that he directed.
A nearby volcano, Mount Tongariro, erupted in August, sending a plume of ash more than 6,000 metres into the atmosphere. It showered the North Island with debris and disrupted domestic air travel.