Drones are starting to become reliable systems for delivery, surveillance, and even warfare. Researchers recently used drones to monitor an active volcano in Guatemala called Santa Maria. Studying an active volcano comes with its own set of challenges like extremely hot volcanic craters and gases and the threat of imminent eruption. This makes close-contact manned studies almost impossible and the only reliable method is through the air. Since, flying a helicopter over a volcano is both inefficient and expensive, drones are the perfect solution.

Santa Maria Active volcano in Guatemala
Santa maria – The active volcano in Guatemala

Researchers from GFZ German Research Center for Geosciences made use of a DJI Phantom 4 Pro to capture volcanic images. The FLIR TAU 2 (9mm lens) thermal imaging camera was attached to the quadcopter as a payload and it flew over Santa Maria. The expedition was spearheaded by Edgar Zorn and his team. Repeated flights were conducted over the dome of the volcano using multiple drones and thermal data was recorded. The research-team could monitor both the thermal feed as well as the 4K visual feed from the drone’s onboard camera. This data proved to be greatly significant as they were able to create a 3D model of the volcano with a spatial resolution of 5 meters per pixel.

What did the drones find in the active volcano?

The drones helped in detecting the different lava dome motions within the volcano: a.) slow radial expansion and growth of the dome; b.) narrow and fast-moving lava extrusion

thermal data from active volcano in Guatemala
Source: Scientific Reports
Thermal data of the active volcano in Guatemala captured by the FLIR camera on the DJI Phantom 4 Pro.

Both these findings can help identify any thermal anomalies within the dome. More importantly, the research was conducted on different timescales that helped to effectively study the growth of the dome and map the surface motions. The research recorded the lava’s distinct flow pattern, its velocity, and the volcano’s surface temperature. This data is critical in assessing and predicting future eruptions.

“We have shown that the use of drones can help to completely re-measure even the most dangerous and active volcanoes on Earth from a safe distance,” Zorn said.

High-quality data collection

The most prominent technique adopted by the researchers was the use of Structure-from-Motion (SfM) – Photogrammetry. Multiple drones flew 100 meters above the dome (300 meters above the launch point) and captured several high-resolution 2D images. Most of the survey photos were taken in perfect alignment with the photographic plane (nadir position). This helped in improving the spatial data of the model. Finally, all the 2D images were post-processed by a computer and converted into a 3D topographic model or a DEM (Digital Elevation Model). The team made use of 2 different DEMs (using drone-captured data and satellite data)  and created a combined high-resolution model of the Guatemala volcano.

SFM model of Santa Maria active volcano
Source: Scientific Reports
The obtained DEM model (above) and the data collected by the drone (below)

“We have equipped a drone with different cameras. We then flew the drone over the crater at various intervals, measuring the movements of the lava flow and a lava dome using a specific type of stereo photography with a precision never seen before,” Zorn stated.

How UAS-based studies will affect volcanology

The core physical challenges faced by scientists and researchers are easily overcome using a UAV-based approach. Drones can fly very close to the volcanic domes and capture high-resolution data. This removes the risk of scientists having to go near the volcano for recording the same data. Drones also bring in never-seen-before data that greatly helps in studying the overall thermal architecture of the volcano and creating a 3D model. The way to predict volcanic eruptions is by repetitive studies that were not possible earlier. Using unmanned aerial systems, active volcanoes can be monitored frequently, thereby, improving assessments of volcanic hazards.

The study on the active volcano in Guatemala by Edgar Zorn has been published in the peer-reviewed journal, Scientific Reports. The published study can be accessed here.