Journal Article

A drone-based prototype technique for monitoring soil degassing at active volcanic craters

Girona, Társilo, Drymoni, Kyriaki, Bacon, Conor A., Williams, Jason, García-Martínez, Noé, Benavente, David, de Moor, Maarten, Westhoff, Matthew, Copple, James, Lev, Einat

2025

Overview

Developing techniques to monitor volcanic activity from safe distances is crucial for advancing scientific knowledge while protecting the safety of field personnel. One of the most demanding tasks in this context is the measurement of soil gas emissions, which offer valuable insights into fluid migration through the shallow crust and act as an early indicator of volcanic unrest and potential eruptive activity. Traditional soil degassing measurements commonly require two operators to be physically present with the instrument, sometimes exposing them to hazardous conditions. In this study, we present a new method for performing soil degassing measurements from a safe distance, using a customized Remotely Piloted Aircraft System (RPAS). This drone-based approach was designed to carry out accumulation chamber measurements in hazardous or otherwise inaccessible areas. We tested the system at four locations around the active crater of Poás Volcano in Costa Rica, where we collected data on CO 2 and H 2 O fluxes, along with soil temperature and moisture. Our results reveal spatial variability in gas emissions and surface conditions across the study sites. A site located on the crater rim (Site 1) showed the highest CO 2 and H 2 O fluxes, indicating active gas release possibly associated with structural features. A second site, located within the crater (Site 2), exhibited elevated H 2 O flux without detectable CO 2 , suggesting localized processes related to moisture transport. Our experiment on another crater site (Site 3) produced a complete and high-quality dataset, demonstrating the operational success of the method. In contrast, measurements at the last crater site (Site 4) were affected by chamber sealing issues and potentially by the influence of volcanic gas plumes. While the experiment faced several challenges, including imperfect ground-sensor contact as well as occasional telemetry interruptions, it successfully demonstrated the feasibility of using drones for soil degassing surveys. Based on these findings, we identify specific areas for improvement and propose future directions to enhance the system reliability and performance. Overall, this method offers a promising tool for extending soil gas measurements to hazardous or hard-to-reach environments, contributing to safer and more comprehensive monitoring of active volcanic systems. Graphical Abstract

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V,SpringerOpen
• Subject: 5. Volcanology / Aircraft / Cameras / Carbon dioxide / Chambers / Craters / Degassing / Drone aircraft / Drones / Earth and Environmental Science / Earth Sciences / Efficiency / Emissions / Environmental monitoring / Eruption / Fluxes / Gases / Geology / Geophysics/Geodesy / Measurement techniques / Methods / Moisture / Monitoring / Monitoring systems / National parks / Observations / Poás volcano / Quantitative Assessment and Modeling of Volcanic Activity / Remotely piloted aircraft / Remotely Piloted Aircraft System (RPAS) / Respiration / Sensors / Soil degassing / Soil gas / Soil gases / Soil properties / Soil temperature / Soils / Spatial variability / System reliability / Telemetry / United States / Unmanned aerial vehicles / Volcanic activity / Volcanic craters / Volcanic gases / Volcanic plumes / Volcano monitoring / Volcanoes / Volcanology