BBC 'should have told' viewers of doctored volcano video

A volcano eruption shown on a BBC Two programme actually used footage from two different volcanoes taken four years apart, the corporation has said.

The eruption of the Calbuco volcano in Chile in April was shown in the first episode of Patagonia: Earth's Secret Paradise last month.

But a dramatic lightning storm seen above the volcano was actually shot at a different location in 2011.

The BBC said viewers should have been told a "composite image" was used.

The programme showed a violent "dirty thunderstorm", in which lightning strikes are seen within the ash clouds from an erupting volcano.

In a blog post, the show's producer Tuppence Stone said such events could be difficult to capture on film and so "it requires special techniques to reveal and portray their true extraordinary nature".

The programme combined time-lapse footage from Calbuco's eruption earlier this year with long-exposure footage of lightning at the Cordon Caulle volcano in 2011.

"These elements had to be combined to create a series of composite images, showing both the size and scale of a Patagonian volcanic eruption, its ash cloud and the repeated strikes of lightning that can occur within it, over many hours," Stone wrote.

"By combining local knowledge, expert advice, and state of the art camera and post production techniques we have been able to reveal to audiences the wondrous scale of an epic natural phenomenon."

However the BBC said viewers should have been alerted to the fact that footage from two different eruptions had been combined.

A statement said: "In order to show viewers the extraordinary spectacle of a dirty thunderstorm with lightning flashes that would be impossible to capture in a single camera, a composite image was put together from footage from two Patagonian volcanoes.

"However, we recognise that this should have been made clear and so have published a blog post to explain the techniques used."