353d8173-fe20-7d7d-e063-3050940aedbd English nonGeographicDataset non geographic dataset British Geological Survey +44 115 936 3100 Environmental Science Centre,Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk pointOfContact 2026-05-03 UK GEMINI 2.3 http://data.bgs.ac.uk/id/dataHolding/13608414 Datafiles from elevated temperature velocity-step tests in a triaxial deformation apparatus 2025-05-14 creation http://data.bgs.ac.uk/id/dataHolding/13608414 Datafiles are from a suite of frictional velocity step experiments on clay-bearing fault gouges, at elevated temperatures up to 180°C. The aim was to test if varying temperature reduces the stability of clay-rich faults, measured by the rate and state friction parameter (a-b). Data were collected in the Rock Deformation Laboratory at the University of Liverpool between Oct 2021 to May 2022 by Dr. Isabel Ashman, as part of her NERC EAO DTP studentship. The datafiles are text files of both the raw voltage and calibrated measurements from triaxial deformation experiments. The stability of synthetic kaolinite clay-bearing fault gouges was found to decrease systematically with elevated temperatures commensurate with those found at typical earthquake depths. In materials containing 25-50% clay, the stability of slip decreased with increasing temperature so that the gouges displayed unstable slip at temperatures between 100 and 180°C. At room temperature the same materials showed stable slip and velocity strengthening characteristics. The reduction in stability with increasing temperature coincides with a greater degree of compaction observed in the gouge microstructure and is inferred to result from progressive loss of water adsorbed on the clay surfaces. These results indicate that clay-bearing fault rocks can nucleate unstable slip at conditions common to the clay-bearing brittle crust; a result that adds to the observations of mature clay-bearing faults in nature that can nucleate and propagate earthquakes. Dr Elisabetta Mariani University of Liverpool Earth, Ocean and Ecological Sciences Herdman Building, 4 Brownlow Street Liverpool L69 3GP not available originator Professor Daniel Faulkner University of Liverpool Professor in Geology and Geophysics School of Environmental Sciences, 4 Brownlow Street Liverpool L69 3GP not available originator Isabel Ashman University of Liverpool Jane Herdman Building, 4 Brownlow Street Liverpool L69 3GP not available originator Enquiries British Geological Survey United Kingdom not available distributor Enquiries British Geological Survey United Kingdom not available pointOfContact notApplicable https://resources.bgs.ac.uk/images/geonetworkThumbs/353d8173-fe20-7d7d-e063-3050940aedbd.png Geology GEMET - INSPIRE themes, version 1.0 2008-06-01 publication Rock mechanics Temperature Earthquakes Clays BGS Thesaurus of Geosciences 2022 revision NGDC Deposited Data Citable Data dataCentre NERC_DDC otherRestrictions licenceOGL Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]" otherRestrictions The copyright of materials derived from the British Geological Survey's work is vested in the Natural Environment Research Council [NERC]. 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Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]" English geoscientificInformation 2021-10-25 2022-05-16 Text file (TXT) witheld Enquiries British Geological Survey United Kingdom not available distributor https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item188220 WWW:DOWNLOAD-1.0-http--download Data download https://doi.org/10.5285/7337c4aa-4fe5-4c8f-abe6-75deb0701e03 WWW:LINK-1.0-http--related Citation Information - Digital Object Identifier (DOI) Ashman, I., Faulkner, D., Mariani, E. (2025). Datafiles from elevated temperature velocity-step tests in a triaxial deformation apparatus. NERC EDS National Geoscience Data Centre. (Dataset). https://doi.org/10.5285/7337c4aa-4fe5-4c8f-abe6-75deb0701e03 information nonGeographicDataset non geographic dataset INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology 2011 publication See the referenced specification false Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 publication See http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:323:0011:0102:EN:PDF false The velocity-step experiments were conducted in a triaxial deformation apparatus in a direct shear slider assembly. In addition to room temperature experiments (23°C), tests were run at controlled experimental temperatures of 60°C, 100°C, 140°C and 180°C (+/-0.4°C). The confining pressure was set using silicon oil at 150 MPa and a pore pressure using deionised water was set at 60 MPa. An axial load was applied using a motor-driven loading column. The initial 2 mm of displacement had a velocity of 0.3 μm/s, then in the ‘velocity-step phase’ the slip velocity was stepped between 3.0 μm/s and 0.3 μm/s every 0.5 mm of slip until the maximum displacement of 5.5 mm was reached.