Pictures you’d only take with a drone

Above is a standard, though admittedly rather impressive, view of the Santa Maria volcano in Guatemala. At right is a less common thermal image of its lava dome.

The latter was made possible – at least safely possible – thanks to the volcanologist’s new best friend, the drone.

Edgar Zorn from the German Research Centre for Geosciences (GFZ) and colleagues ran a series of repeated survey flights with optical and thermal imaging cameras to reveal that the volcano shows movements on two different time scales: slow expansion and growth of the dome, and fast extrusion of viscous lava.

They flew the drone over the crater at various intervals, measuring the movements “using a specific type of stereo photography with a precision never seen before”, Zorn says.

By analysing the data, they were able to determine the flow velocity, movement patterns and surface temperature of the volcano – all important parameters for predicting the danger of explosive volcanoes – as well as the flow properties of the lava.

The two cameras took both high-resolution photos and thermal images. Using a special computer algorithm, the researchers were able to create a 3D topography and temperature model with a resolution of only a few centimetres.

“The 3D models of the various flights must be positioned exactly so that they can be compared,” says Zorn. “This requires painstaking detail work, but the effort is worth it because even minimal movements become immediately visible.”

As GFZ colleague Thomas Walter notes: “A regular and systematic survey of dangerous volcanoes with drones seems to be almost within one’s grasp.”

The research and findings are described in a paper in the journal Science Reports.