AUTHOR=Fidani C. , Gherardi F. , Facca G. , Pierotti L. TITLE=Correlation between small earthquakes and CO2 anomalies in spring waters: a statistical experiment on the probability of seismic occurrence JOURNAL=Frontiers in Earth Science VOLUME=Volume 11 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1128949 DOI=10.3389/feart.2023.1128949 ISSN=2296-6463 ABSTRACT=We correlated carbon dioxide (𝐢𝑂 2 ) time series detected at the Gallicano site in Tuscany, Italy, with low-magnitude earthquakes occurred in the surrounding area between 2017 and 2021. The 𝐢𝑂 2 irregular component distribution was analyzed by a Pearson type VII fit, and its cumulate probability by the Gauss's hypergeometric function, to statistically evidence anomalous fluctuations. We calculated the Matthews correlation between gas concentrations and low-magnitude earthquakes by defining a binary occurrence of 𝐢𝑂 2 anomalies and seismic events. A positive correlation was highlighted by a time lag between the digital series, which resulted in 𝐢𝑂 2 anomaly detections ahead of the earthquake time of two (2) days. The correlated earthquakes were mainshocks of local magnitude 1.2 to 3.6, with epicenters within 40 π‘˜π‘š from the Gallicano site. Correlations among rainfalls, 𝐢𝑂 2 concentrations and earthquakes were also considered, showing that only few rainfall events were followed by a 𝐢𝑂 2 anomaly, mostly a day late. Description of the study area Eliminato: 2018 Eliminato: Methods 2017-2021 period. The structures identified by the DISS Working Group (2021) are also shown (blue rectangles: 146 Composite Seismogenic Sources; yellow rectangles: Individual Seismogenic Sources; blue curved lines: 148 Subduction Sources). Red dots are 𝑀 𝑀 >6 earthquakes extracted from the CPTI15 v 4.0 catalog (Rovida et al., 2022).