Distribution of CO2 and CH4 emissions in Italy
To the left - Distribution of CO2 emissions, seismotectonic elements and tectonic domains. CO2 emissions are shown in (a) red when discussed in the text of the article; (b) gray if present in areas with heat flux > 70 mW/m2; (c) green in all other cases. The diagram above shows the distribution of CO2 emissions in the different tectonic regimes active today. It should be noted that 61% of CO2 emissions are present in Tyrrhenian areas of crustal thinning and only 18% in the extensional areas of the Apennines where strong earthquakes occur.
To the right - Distribution of CH4 emissions, seismotectonic elements and tectonic domains. CH4 emissions are shown in (a) red when discussed in the text of the article; (b) gray if believed to be biogenic in nature and/or if located within 5km of a peat or coal emergence; (c) yellow in all remaining cases. The diagram above shows the distribution of CH4 emissions in the different tectonic regimes active today. It should be noted that 54% of CH4 emissions are present in the compressive environments of the foothills of the Apennines, the Po Valley and Sicily.
Distribution of CO2 and CH4 emissions in Italy
left - Distribution of CO2 emissions. Tectonic domains, seismogenic sources and transverse lineaments are shown. Selected data points are shown in red if they are individually discussed in the paper, otherwise in white. The pie chart shows the distribution of CO2 emissions in the different active tectonic domains. Notice that as many as 61% of the CO2 emissions fall in the area of rifting and mantle upwelling.
Right - Distribution of CH4 emissions. Tectonic domains, seismogenic sources and transverse lineaments are shown. Selected data points are shown in red if they are discussed in the paper, otherwise in yellow. The pie chart shows the distribution of CH4 emissions in the different active tectonic domains. Notice that 54% of these emissions fall in areas of active contraction.
The interactions between different natural fluids, such as thermal springs, emissions of carbon dioxide, methane and other gases, and Italy's seismotectonics were illustrated in the study 'The seismotectonic significance of geofluids in Italy' just published in Frontiers in Earth Sciences journal.
One of the topics that geophysics has recently been carefully addressing is the understanding of the mechanisms of release into the atmosphere of geofluid emissions deriving from the geodynamic activity of the planet and, in particular, how much they contribute to the global greenhouse gas balance.
"In the study", explains Paola Vannoli, researcher of the Rome 1 Section of the INGV, “aalso analyzing greenhouse gases such as methane and carbon dioxide, we investigate which are the geological and tectonic contexts that allow them to escape from the ground, and therefore their release into the atmosphere”.
The investigation of these mechanisms was based on the analysis of multidisciplinary data and was conducted on a national scale. It can contribute, on the one hand, to the quantification of greenhouse gas emissions and, on the other hand, to improve the understanding of the tectonic processes that give rise to large earthquakes.
“Usually this type of studies and correlations are carried out on a global scale or, conversely, in great detail on a regional and municipal level. We, on the other hand, have investigated these phenomena on an, so to speak, 'intermediate' scale, i.e. at a national level" explains Paola Vannoli, who continues “Italy proved to be the ideal place to carry out this study for various reasons. First of all, because in our country we have a good knowledge of seismicity and tectonics underway today as well as historical seismicity and the geological history of the past; in Italy, then, numerous very different geodynamic processes and contexts coexist; we have more than a century of data relating to geofluids such as, for example, the precious work of cataloging and describing thermal waters carried out by Luigi Tioli at the end of the nineteenth century; finally, we are one of the areas with the highest release of carbon dioxide and methane in the world”.
“The results of our research” continues Paola Vannoli “indicate that thermal springs and carbon dioxide emissions are decidedly prevalent in volcanic areas near the Tyrrhenian coast of Tuscany, Lazio and Campania, where the crust undergoes stretching and thinning. In the few cases in which these geofluids are present in the internal areas of the Apennines, they are mostly localized on the margins of large extensional faults, such as those that caused the earthquakes of 24 August and 30 October 2016, often in correspondence with tectonic structures transversal to the Apennine chain. Contrary to what is usually believed, we can say that carbon dioxide emissions only marginally affect the areas in active extension today home to strong earthquakes such as those of 2016. Conversely, methane emissions instead characterize the environments of the foothills of the Apennines and the Plain Padana, sites of compressive faults capable of earthquakes of moderate magnitude, of the type that struck Emilia in 2012”.
In conclusion, the researcher states “Briefly, in Italy the release of geofluids seems to be controlled by two determining factors: by the tectonic deformation in progress, which explains the concentration of carbon dioxide emissions and thermal springs in areas of crustal thinning and the concentration of methane emissions in compressive areas , and by the existence of deep crustal discontinuities, which were created during the long geological history of the peninsula and which explain the presence both of carbon dioxide emissions in the internal areas of the Apennines and of important fields of mud volcanoes.” The research will continue to better understand the interactions between the manifestations of geofluids and the presence of geological discontinuities capable of controlling the modalities of seismic release".
Link: https://www.frontiersin.org/articles/10.3389/feart.2021.579390/full
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The interaction between seismotectonics and the emission of geofluids in Italy
The interactions between the different natural fluids, such as thermal springs, emissions of carbon dioxide, methane and other gases, and the seismotectonics of Italy were illustrated in the study 'The seismotectonic significance of geofluids in Italy'. The study has just been published in the journal Frontiers in Earth Sciences.
One of the issues that geophysics has recently been addressing with attention is the understanding of the release mechanisms of geofluid emissions into the atmosphere from the planet's geodynamic activity and, in particular, how much they contribute to the global greenhouse gas balance.
"In the study", explains Paola Vannoli, researcher of the Rome 1 Section of the INGV, "we investigate what are the geological and tectonic contexts that allow greenhouse gases to escape from the ground to the atmosphere, by analyzing greenhouse gases such as methane and carbon dioxide”.
The investigation of these mechanisms was based on the analysis of multidisciplinary data and was conducted on a national scale.
It can contribute, on the one hand, to the quantification of greenhouse gas emissions and, on the other hand, to improve understanding of the tectonic processes that give rise to strong earthquakes.
“Usually this type of studies and correlations are carried out on a global scale or, vice versa, in great detail at the regional and municipal level.
We, on the other hand, have investigated these phenomena on an 'intermediate' scale, so to speak, that is at a national level", explains Paola Vannoli, who continues "Italy has proved to be the ideal place to carry out this study for various reasons. First of all, because in our country we have a good knowledge of seismicity and tectonics in progress today as well as of historical seismicity and geological history of the past ; in Italy, then, numerous very different geodynamic processes and contexts coexist; we have more than a century of data relating to geofluids such as, for example, the precious work of cataloging and describing thermal waters carried out by Luigi Tioli at the end of the nineteenth century; finally, we are one of the areas with the highest release of carbon dioxide and methane in the world".
"The results of our research" continues Paola Vannoli "indicate that thermal springs and carbon dioxide emissions are decidedly prevalent in the volcanic areas near the Tyrrhenian coast of Tuscany, Lazio and Campania, where the crust undergoes stretching and a thinning. In the few cases in which these geofluids are present in the internal areas of the Apennines, they are mostly located on the edge of large extensional faults, such as those that caused the earthquakes of 24 August and 30 October 2016, often in correspondence with tectonic structures transversal to the Apennine chain. Contrary to what is usually believed, we can affirm that carbon dioxide emissions only marginally affect the areas in active extension today the site of strong earthquakes such as those of 2016. On the other hand, methane emissions characterize the environments of the Apennines and the Po Valley, sites of compressive faults capable of earthquakes of moderate magnitude, of the type that struck Emilia in 2012".
In conclusion, the researcher states "Briefly, in Italy the release of geofluids seems to be controlled by two factors determining: by the tectonic deformation in progress, which explains the concentration of carbon dioxide emissions and thermal springs in areas of crustal thinning and the concentration of methane emissions in compressive areas, and from the existence of deep crustal discontinuities, which were created during the long geological history of the peninsula and which explain the presence of both carbon dioxide emissions in the internal areas of the Apennines and of important fields of volcanoes of mud. Research will continue to better understand the interactions between the manifestations of geofluids and the presence of geological discontinuities capable of controlling the modalities of seismic release”.
Link: https://www.frontiersin.org/articles/10.3389/feart.2021.579390/full