Abstract
Seismic faults paradoxically combine high frictional strength, which promotes stress accumulation and should hinder slip, with large seismic displacements. Among proposed dynamic weakening mechanisms, shear heating is crucial because it triggers decarbonation and CO₂ production. In carbonate faults, this process generates transient CO₂ pressurization that can modulate rupture dynamics and promote supershear propagation, yet the amount and pressure of produced CO₂ remain poorly quantified. We investigate carbonate faults in the Apennines, Italy, a region affected by Mw≤7.1 earthquakes. Integrating nano-scale observations of fault surfaces with mineralogical and isotopic constraints, we develop a stoichiometric-thermodynamic model linking seismic decarbonation to Mw 5.9–6.5 earthquakes. Individual events can produce up to 12 tons of CO₂, generating quasi-lithostatic pressures ( ~ 196 MPa) under undrained confinement and supra-hydrostatic pressures (76–134 MPa) under drained conditions. Here, we conclude that seismic CO₂ pressurization can sustain dynamic slip and enhance the destructive potential of earthquakes in carbonate terrains.
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Data availability
All data used in this work are available in the Supplementary Information (Supplementary Figs. 1–8 and Supplementary Tables 1–7) and in a public data repository (https://doi.org/10.6084/m9.figshare.31007884). All the figures have been edited with Adobe Illustrator (https://www.adobe.com/produ cts/illustrator.html). Historical and instrumental seismological data of earthquakes in the Apennines (Figs. 5, 6, Supplementary Fig. 1, and Supplementary Table 4) are from the catalogs of Istituto Nazionale di Geofisica e Vulcanologia, INGV, freely available at https://emidius.mi.ingv.it/CPTI15-DBMI15/ and https://terremoti.ingv.it/en/tdmt, respectively. The elevation data used for the Supplementary Fig. 1 was obtained from the Open Digital Elevation Model (OpenDEM) freely available at https://www.opendem.info/archiv_2020.html. Pressure computation applying the Span and Wagner’s equation of state was performed using the open source LONER18 software available at https://fluids.unileoben.ac.at/Computer.html. Pressure computation applying the Peng-Robinson’s equation of state was performed using the WolframAlpha online resource available at https://www.wolframalpha.com/input?i=Peng-Robinson+equation+of+state. Pressure computation applying the Famin et al.21 approach was performed using a Python code provided in the supplementary information. Masses of CO2 shown in Fig. 5 (A to G) are reported in the Supplementary Table 3. Correspondence and requests for materials should be addressed to Manuel Curzi, although all data are publicly available online (https://doi.org/10.6084/m9.figshare.28562510) and in the Supplementary Information.
Code availability
The Python code used to calculate CO2 pressure under drained conditions (which requires prior installation of the NumPy, Matplotlib, and SciPy libraries) is provided as text in the Supplementary Information.
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Acknowledgements
This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next-GenerationEU (National Recovery and Resilience Plan—NRRP, Mission 4, Component 2, Investment 1.3—D.D. 1243 2/8/2022, PE0000005). We thank M. Mercuri and F. Agosta for their support during sampling along the Mt. Capo di Serre Fault. We thank E. Spagnuolo and C. Marone for helpful discussions on experimental seismic faulting in carbonates.
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The study was conceived collaboratively by all authors. M.C., A.B., and E.C. leading the project. M.C., A.B., and E.C. conducted fieldwork and sampling. M.C., A.B., A. Cavallo, and E.C. performed optical and FESEM analyses. L.A. carried out the XRD analysis. C.B. and I.B. conducted stable isotope analyses. M.C. led the final modeling with contributions from all authors. C.B., I.B., A. Caracausi, and G.R. advised geochemical aspects of final modeling. M.C. processed preliminary and final images, integrating feedback from the team. M.C. and A.B. drafted the paper, incorporated feedback from all authors, and, with their input, finalized the text. E.C. secured project funding.
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Curzi, M., Billi, A., Aldega, L. et al. Earthquake dynamics sustained by seismic CO2. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69174-w
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DOI: https://doi.org/10.1038/s41467-026-69174-w
