News from the Earth Sciences
UCL Earth Sciences

News from the UCL Hazard Centre

18 March 2018

Developing Low-Cost CO2 Sensors for Monitoring Degassing Volcanoes.


Geochemical surveillance is essential for reducing risk at actively degassing volcanoes. Variations in concentration and compositions of gases can be indicators of magma ascent or changes in hydrothermal system dynamics, so monitoring is important for the timely detection of unrest. The gases themselves can also present a major health hazard, with impacts ranging from aggravation of respiratory conditions and skin inflammation, to asphyxiation and death. A key challenge for monitoring is that degassing can occur over large areas and concentrations can change rapidly. In an ideal scenario, networks of instruments capable of providing real-time information would be installed across the degassing area, but conventional methods are usually cost-prohibitive.

In a joint initiative with the Dept. of Computer Sciences, the Hazard Centre has been developing low-cost CO2 sensors, using commercially available components, that are capable of monitoring gases and uploading the data to the internet in real-time. In December 2017, Chris Kilburn, Lara Smale (UCL Hazard Centre) and Steve Hailes (Dept. of Computer Sciences) met with collaborators from the Montserrat Volcano Observatory and the UWI Seismic Research Centre to test the first prototypes at Sulphur Springs, Saint Lucia. This is an active hydrothermal area that is not only a site of volcanological interest but a major tourist attraction on the island that brings large numbers of people into the area.

2018-03- Hazard Centre

Image: Dr. Chris Kilburn with prototype CO2 fluxmeters in an area of fumarolic activity at Sulphur Springs, Saint Lucia. The rate of gas released from the soil was measured and transmitted to a base-station, which then uploaded the data to the internet (until the acidic gases corroded the connections on the sensor power supply!(photo taken by Reni Magbagbeola)


Sensors for measuring soil CO2 flux and ambient concentrations were installed in areas of diffuse fumarolic activity and along pathways with the highest foot traffic. Data was then collected on both the gases and the ability of the components to withstand the hot and acidic conditions. An ambient CO2 sensor was also installed for a long-term test, that at the time of writing was still transmitting data back to UCL. The results are currently being used to improve designs and to inform the development of sensors for other gas species such as SO2 and H2S. The ultimate aim is to make successful designs and the accompanying software freely available online.

The Hazard Centre will be returning to Saint Lucia in March for further field tests. It is hoped that the sensors will eventually be integrated into a live volcano monitoring system there and opportunities for utilising them in community engagement projects are also being explored. 

Thanks go to all those involved, and especially to the Soufriere Development Foundation who have provided access to the site and facilities.