In April, 2009, a magnitude 6.3 earthquake rocked the city of L’Aquila in the Abruzzi region of central Italy. Immediately after the tremor, researchers began measuring CO2 which was being emitted from nearby hotsprings.
Few would have suspected that more than a decade later, researchers would reveal the gas bubbling up from beneath Earth’s surface would trigger such a devastating quake which killed more than 300 people.
Beneath L’Aquila are two groundwater aquifers – permeable rocks which transmit groundwater – where the researchers began measuring the CO2.
They discovered huge bubbles of CO2 which travelled up through the rocks, triggering earthquakes as they did so.
The team from the Italian National Institute of Geophysics and Volcanology believe the CO2 travelled up, weakening the crust and making it more prone to tremors.
They said in a statement: “The Apenninic earthquakes in the last decade are clearly associated with the ascent of deeply derived CO2.”
Study coauthor Giovanni Chiodini, a geologist at the Italian National Institute of Geophysics and Volcanology, said: “I think there is feedback between the two.”
On the other hand, the team also believe that the initial small tremors of a quake may disrupt the CO2 bubbles, forcing them to shoot upwards and causing more powerful quakes.
They said: “The analysis of groundwaters makes it possible to investigate relatively large areas and related tectonic processes at regional scale.”
By monitoring tremors in the region for more than a decade, the team were also able to deduce how much CO2 was produced over a 10 year period by seismic activity.
They found a staggering 1.8 million tonnes of CO2 was released over the decade, which is equivalent to the carbon emitted from 350,000 cars driven for a year.
The team now believe these figures should be factored in when thinking about CO2 emissions in terms of saving the planet.
They wrote: “The study of groundwaters in tectonically active areas would be a powerful tool to better estimate the global budget of tectonic carbon dioxide emissions into the atmosphere.
“We hope that a continuous monitoring of water springs is the best way to track deeply produced CO2 emissions to better understand the causal relationship with seismicity.”