Quantification and Origin of the Anomalous CO2 Release Accompanying L'Aquila 2009 Earthquakes
Abstract
Deep pressurised pockets of CO2 were recognised to be involved in two seismic crisis of the Apennines that preceded the Amatrice earthquake: the 1997 Umbria-Marche and the 2009 L'Aquila earthquakes (LAE). Here we focus on the LAE that in 2009 caused 309 victims, 1600 injured people and 80000 displaced persons. A previous investigation highlighted that important amounts of deeply derived CO2 enter in the two aquifers outcropping in the LAE area. Here, we update the previous dataset with the results of other eight campaigns, the last of which in September 2015, with the aim of evaluating any variation in the flux of deep CO2 related to the 2009 earthquakes. This long time series of chemical and isotopic compositions of the main springs in the area highlights an evident anomalous CO2 release associated with the earthquakes. In particular, starting from the date of the main shock, we observed an anomalous release of CO2 that lasted for years and involved hundred thousands tonnes of deeply derived gas. In order to interpret this anomaly we re-considered DinSAR data discovering that a 4 years long inflation preceded the LAE. We argue that the LAE event was anticipated by a years-long deep pressurization stage. Few months before the LAE, concurrently with the beginning of the seismicity, the ground movement changed from inflation to an accelerating deflection that culminated in the April 2009 mainshock. In our model, the observed anomalous release of deep CO2 in the years following the LAE is the last step of a process that began in 2005 causing the observed period of inflation of the area affected by the earthquakes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S43F3201C
- Keywords:
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- 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGYDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7230 Seismicity and tectonics;
- SEISMOLOGY