This dataset contains raw data from synthetic and experimental velocity steps analyzed using the MATLAB routine ‘steadystate.m’, as presented by Giacomel, P., Faulkner, D.R., Lambert, V., Allen, M.J (2024): ‘steadystate: A MATLAB-based routine for determining steady-state friction conditions in the framework of rate- and state- friction analysis’ – GSA, Geosphere. The data is provided in .zip folder containing the Velocity Steps and the outputs from steadystate.m, along with the scripts used to generate the figures shown in the Manuscript and Supplementary Material. The folder ‘Velocity_Steps’ notably contains the complete suite of mechanical data (subfolder ‘Mechanical_Data), the modelled rate- and state- friction parameters (subfolder ‘Modelled_RSF_Parameters SlipLaw’) obtained by assuming steady state at different displacements, as well as the linear detrended end members (i.e., at short to large displacements) fitted via inverse modelling (subfolder ‘Detrended_Velocity_Steps + Fit-Inversions’). Such observations were foundational for the development of the steadystate.m routine. Each subfolder is accompanied by a README.txt file that reports on the link between the raw .txt data with the MATLAB scripts generating the associated figures. For the sepiolite fault gouge used during the friction velocity steps, please refer to: Sánchez-Roa, C., Jiménez-Millán, J., Abad, I., Faulkner, D. R., Nieto, F., and García-Tortosa, F. J., 2016, Fibrous clay mineral authigenesis induced by fluid-rock interaction in the Galera fault zone (Betic Cordillera, SE Spain) and its influence on fault gouge frictional properties: Applied Clay Science, v. 134, p. 275-288.

This dataset contains raw experimental direct shear testing data as presented by "Ougier-Simonin, A., Castagna, A., Benson, P. and Walker, R. (2017). Direct shear characterisation of simulated clay-bearing gouges: a case study from the Pernicana Fault System (Mount Etna, Sicily). In EGU 2017 General Assembly Conference Abstracts (p. 15794)". The data is provided in a .zip folder containing the files of 12 experiments that are accompanied by a README file for introduction. Files format is Microsoft Excel Worksheet (.xlsx) and data are tabulated. Each file contains the corresponding relevant sample’s details, and each column of data is clearly labelled, units included. For each experiment, time, axial force, axial displacement, axial stress, confining displacement, confining pressure, internal temperature, and axial delta P were recorded. Details of calculations for shear stress and coefficient of friction are also provided. Twelve gouge (rock powder) samples of Monte Salici sandstone (Numidian Flysch, Appenninic-Maghrebian Chain; Sicily), ‘Comiso’ limestone (Ragusa Formation; Sicily) and Quaternary Clays (blue-grey clay in Fiumefreddo, Sicily) were tested in direct shear using sliding holders in triaxial compression at a range of confining pressures of 10, 30 and 50 MPa. Clay and sandstone samples tests were conducted at 0.3 microns per second of axial displacement rate; limestone and mixed gouges tests were conducted at 1 micron per second. Maximum displacement: ca. 9.8mm. All tests done at room temperature. The experiments were conducted by Drs A. Castagna and A. Ougier-Simonin using the MTS815 Rock Testing System in triaxial configuration and homemade sliding holders in the Rock Mechanics and Physics Laboratory of the British Geological Survey; both responsible for the collection and initial interpretation of the data.