Monitoring Gas Emissions from Volcanoes to Predict Volcanic Activity

To understand and predict the behaviour of volcanoes an increasing number of scientists are combining geological monitoring and geochemical models. By measuring and monitoring the prevalence of gases like CO2, scientists hope to be able to better predict the likelihood of volcanic eruptions.

In 2010 Iceland’s Eyjafjallajökull volcano erupted, releasing 250 million cubic metres of ash into the atmosphere. The eruption disrupted 100,000 flights and 10 million journeys, bringing the global aviation industry to a standstill and costing hundreds of millions of dollars. [1]

In the past predicting when one of the world’s 1,500 volcanoes is about to erupt has been based on monitoring and measuring the seismic activity around the site. However, since the 1970s correlation spectrometers have been used to measure the levels of sulfur dioxide in the volcanic plume as scientists began to understand that higher levels of gas emission from a volcanic site indicates a higher chance of eruption.

In more recent times, using geochemical models, a growing body of research and evidence shows measuring the levels of emitted CO2 can be used to predict the risk of an eruption.

Carbon Dioxide Gas Monitoring to Predict Volcanic Activity

Sitting to the north of Sicily, Italy’s Mount Stromboli has erupted almost continuously for over 2,000 years. [2] This volatile island is the perfect environment for volcanologists to test their theories, confident that they won’t need to wait too long for an eruption.

When magma begins to rise to the surface its pressure decreases, releasing gases into the environment. This process, known as degassing, [4] releases volatiles into the air, including water (H2O), carbon dioxide (CO2) sulfur dioxide (SO2) and hydrogen sulfide (H2S).

These gases escape through fumaroles, appearing as plumes of smoke. Scientists have discovered that by studying the composition of this gaseous mixture and monitoring fluctuations in their composition, they may be better able to predict the likelihood of volcanic eruption.

Between 2007 and 2012 Italian scientists at the Stomboli Volcano [3] used fixed cameras, a Multi-GAS analyser (to monitor SO2 and CO2 fluxes) and continual fumerole temperature recording to monitor geological and geochemical variations at the site.

An Edinburgh Sensors’ Gascard NG gas sensor was used, within the Multi-Component Gas Analyser System (Multi-GAS), to calculate the CO2 concentrations within the volcanic flume. Located 2m inside the volcanic fracture, the automated instruments provided CO2 recordings within a measurement range of 0-3000 ppm; at an impressive accuracy range of ±2 % and a resolution of 0.1 ppm.

The Multi-GAS system allowed researchers to map the long-term CO2 trends at the volcano, establishing a mean value, and recording variations. When considered with all other data collected at the site, analysis shows correlation between CO2 spikes and volcanic activity.

Monitoring of the degassing activity can also help scientists gain an insight into the ‘plumbing system’ within a volcano. Beneath the surface, the variations in the structure of the earth, the storage of magma and its periodic recharging (as fresh magma is introduced) are all important processes which are important to monitor. CO2 monitoring enables researchers to define and then spot and track ‘signature’ styles of degassing in order to determine what is happening underground.