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In order to comprehend and predict the behavior of volcanoes, many scientists are combining geochemical models and geological monitoring. Scientists hope that they can better predict the likelihood of volcanic eruptions by measuring and monitoring the prevalence of gases like carbon dioxide (CO2).
Iceland’s Eyjafjallajökull volcano erupted in 2010, ejecting 250 million cubic meters of ash into the atmosphere. The eruption caused disruption to 100,000 flights and 10 million journeys, brought the global aviation industry to a halt, and cost hundreds of millions of dollars. 
Previously, the eruption of any one of the world’s 1,500 volcanoes was predicted based on monitoring and measuring the seismic activity around the site. However, correlation spectrometers came into use in the 1970s to measure the levels of sulfur dioxide (SO2) in the volcanic plume when it became understood that higher levels of gas emission from a volcanic site indicated a higher chance of eruption.
Recently, with the help of geochemical models, research and evidence has demonstrated that levels of emitted CO2 can be measured to predict the risk of a volcanic eruption.
Carbon Dioxide Gas Monitoring to Predict Volcanic Activity
Italy’s Mount Stromboli, situated north of Sicily, has erupted nearly continuously for more than 2,000 years . This volatile island presents the perfect environment for volcanologists to test their theories, since they can be confident that they need not wait for a long period for an eruption to occur.
When magma rises to the surface its pressure decreases, which in turn releases gases into the environment. Through this process of degassing , volatiles are released into the air, including CO2, SO2, water (H2O), and hydrogen sulfide (H2S).
These gases appear as plumes of smoke as they escape through fumaroles. By studying the composition of this gaseous mixture and monitoring fluctuations in their composition, scientists have discovered that they can better predict the likelihood of a volcanic eruption.
Between 2007 and 2012, Italian scientists at the Stromboli Volcano  employed fixed cameras, continual fumerole temperature recording, and a Multi-Component Gas Analyzer System (Multi-GAS analyzer), (for monitoring CO2 and SO2 fluxes), to track geochemical and geological variations at the site.
To calculate the CO2 concentrations within the volcanic flume, an Edinburgh Sensors’ Gascard NG gas sensor was employed within the Multi-GAS analyzer. The automated instruments, located 2 m inside the volcanic fracture, recorded CO2 within a measurement range of 0-3000 ppm, at a resolution of 0.1 ppm, and at an impressive accuracy range of ±2%.
The Multi-GAS system enabled scientists to chart the long-term CO2 trends at the volcano, thus establishing a mean value, and recording variations. When combined with all other collected site data, the analysis showed a correlation between volcanic activity and CO2 spikes.
Scientists can also gain an insight into the ‘plumbing system’ within a volcano by the monitoring of the degassing activity. Underground, the key processes that are important to monitor are the variations in the earth structure, and the storage of magma and its periodic recharging (as fresh magma is introduced). CO2 monitoring allows scientists to define, spot, and track ‘signature’ styles of degassing in order to determine the activities occurring beneath the surface.
The degree of CO2 emission from volcanic vents can be used to determine the likelihood of an eruption. Shutterstock | Brandon B
Measuring Dissolved Carbon Dioxide in Volcanic Aquifers
It should be noted that not every gas emitted during the degassing process makes it to the surface. Some become condensed or are dissolved into fluids in groundwater, creating hydrothermal aquifers, whose constitution is of increasing interest to researchers.
Although measurements of water pH and carbonic acid (formed as CO2 which rises to the surface and comes into contact with water) can indicate the level of CO2, a group of Italian researchers have created an automated monitoring system, employing an infrared spectrometer based on the principles of Henry’s Law. 
The dissolved CO2 in natural waters around the Stromboli earthquake was measured by the automated system which allowed researchers to establish what was described as a “clear correlation between the changes in PCO2 in the thermal aquifer and the changes in volcanic activity.”
Once the baseline was defined, researchers monitored the PCO2 levels around the Stromboli Volcano. After monitoring the daily averages of PCO from January 2009 to May 2012, researchers identified the correlations within the data, relating increased concentrations of CO2 to volcanic activity.
Underwater eruptions can result in CO2 accumulating in aquifers. Shutterstock | kridsada kamsombat
Combining Gas Sensors with a UAV for Extreme Measurements
As crater temperatures reach extreme levels, accurate data collection on volcanoes can be hazardous. To tackle this problem, scientists at the University of Costa Rica  use UAVs (drones), equipped with miniature gas spectrometers, to enable accurate measurements of the compounds present in the gas plumes above volcanoes.
Flying on a pre-fixed course, the VW-100’s 10 megapixel camera enables operators on the ground to view the progress of drone when it enters inhospitable areas to take the necessary measurements. This drone-sensor array can operate within volcanic plumes and provide real-time, accurate measurements.
The Gascard NG
The Edinburgh Sensors’ Gascard NG has a proprietary NDIR technology, enabling the unit to provide real-time measurement of CO2 levels from 0 to 500 ppm to 0-3%. This high quality, low maintenance sensor is best-suited for the accurate scientific measurements needed by volcanologists.
After data collection, true RS232 communications and optional on-board LANsupport allow data to be easily accessible and shared from the unit. The device's firmware can support modern graphical display or a 4-segment LCD, if needed.
The Gascard NG from Edinburgh Sensors
The Gascard NG can be integrated into OEM applications, and can be seamlessly interoperated with other technologies, such as the Multi-GAS system used in Italy.
The unit is built to exacting standards for use in field applications, and provides a flawless, low-maintenance solution. It can perform in extreme environments, thanks to its tested and proven extensive temperature compensation and on-board barometric pressure correction.
Download the Gascard NG Brochure for More Information
- EUROCONTROL - Report on the 2010 Ash Clouds Impact on Air Traffic
- Volcano Report on Stromboli Activity
- S. Inguaggiato et al., Development of an Automated Monitoring System and First Application to the Stromboli Volcano, Annals of Geophysics, 54, 2011
- S. Calvari et al., Major Eruptive Style Changes Induced by Structural Modifications of a Shallow Conduit System, Bull Volcano, 76, 2014
- Tico Times - Unmanned Drones to Explore Mystery of Volcano Plumes
This information has been sourced, reviewed and adapted from materials provided by Edinburgh Sensors.
For more information on this source, please visit Edinburgh Sensors.