089b258b-84ed-24e8-e063-0937940a88b8 English dataset British Geological Survey +44 115 936 3100 Environmental Science Centre, Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk pointOfContact 2026-03-04 UK GEMINI 2.3 http://data.bgs.ac.uk/id/dataHolding/13608117 WGS 84 (EPSG::4326) Triaxial compressive strength data of tests conducted at elevated temperature on hydrothermalised basalt samples from Osa Peninsula (Costa Rica) and oceanic crust basalt from Cocos Plate 2023-09-26 creation http://data.bgs.ac.uk/id/dataHolding/13608117 This dataset contains raw (clean but not interpreted) triaxial compressive strength data of tests conductive at elevated pressure and temperature as outlined in "Vannucchi, P., Clarke, A., de Montserrat, A., Ougier-Simonin, A., Aldega, L., & Morgan, J. P. (2022). A strength inversion origin for non-volcanic tremor. Nature Communications, 13(1), 2311. https://doi.org/10.1038/s41467-022-29944-8". The data is provided in a .zip folder containing the files of 5 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, axial strain A and B, axial average strain, circumferential extensometer, circumferential strain, volumetric strain, internal temperature, and axial delta P were recorded. Triaxial testing was undertaken using the MTS 815 servo-controlled stiff frame inside a vessel capable of a confining pressure up to 140 MPa at the Rock Mechanics and Physics Laboratory, British Geological Survey, UK. The confining cell is fitted with external heater bands and utilizing utilizes cascade control from internal and external thermocouples (accurate to ± 0.5°C). An initial axial pre-load of 2.3 kN was applied, to ensure a stable contact and alignment of the platens. The confining pressure vessel was then closed and filled with mineral oil confining fluid. The axial pre-load was maintained whilst the confining pressure was applied at 2 MPa/min to 60 or 120 MPa; these values were chosen to approximately bracket the pressures at the up-dip limit of seismic nucleation, corresponding to 2 – 4 km depth (Arroyo et al., 2014). At this point, whilst held in axial force and confining pressure control, the rig was heated at 2°C/min to 60°C to approximate the average temperature conditions at the depth of the up-dip limit of seismic nucleation (Harris and Spinelli, 2010). The samples were then left for approximately 1 hour allowing thermal equilibrium to be reached throughout the confining fluid and the samples. Once stable, axial loading was initiated in constant axial strain rate control at a rate of 5.0 x 10-6 s-1 until macroscopic failure occurred or a significant amount of post peak-stress axial strain was recorded (between 2% and 5%). We note that one test was conducted at the higher temperature of T=120°C with a result within 2.5% of the strength at T=60°C (Table 1). As this is below the expected sample-to-sample variability, no further temperature studies were conducted. The axial load, axial load actuator displacement, axial stress (s1), differential stress (Q=s1 - s3), confining pressure Pc (= s2= s3), confining pressure actuator displacement, axial strain (eax), circumferential strain (ecirc) and temperature were monitored throughout at sampling frequencies of 1s and 0.5kN. File names are: YYYY-MM-DD_LabProjectNumber_SiteName-SampleNumber Alex Clarke Royal Holloway University of London not available originator Enquiries British Geological Survey 0115 936 3143 0115 936 3276 Environmental Science Centre, Nicker Hill, Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk distributor Enquiries British Geological Survey 0115 936 3143 0115 936 3276 Environmental Science Centre, Nicker Hill, Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk 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/089b258b-84ed-24e8-e063-0937940a88b8.png Geology GEMET - INSPIRE themes, version 1.0 2008-06-01 publication Compression tests Deformation (materials) Stress Basalt Igneous rocks Brittle deformation Elastic theory Strain 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]. No part of this work may be reproduced or transmitted in any form or by any means, or stored in a retrieval system of any nature, without the prior permission of the copyright holder, via the BGS Intellectual Property Rights Manager. Use by customers of information provided by the BGS, is at the customer's own risk. In view of the disparate sources of information at BGS's disposal, including such material donated to BGS, that BGS accepts in good faith as being accurate, the Natural Environment Research Council (NERC) gives no warranty, expressed or implied, as to the quality or accuracy of the information supplied, or to the information's suitability for any use. NERC/BGS accepts no liability whatever in respect of loss, damage, injury or other occurence however caused. Available under the Open Government Licence subject to the following acknowledgement accompanying the reproduced NERC materials "Contains NERC materials ©NERC [year]" English geoscientificInformation British Geological Survey Gazetteer: Geographical hierarchy from Geosaurus 1979 creation COCOS PLATE [id=978000] British Geological Survey Gazetteer: Geographical hierarchy from Geosaurus 1979 creation COSTA RICA [id=806000] ISO 3166_1 alpha-2 2009 revision CR ISO 3166_1 alpha-3 2009 revision CRI -84.2300 -83.2800 8.3700 8.7200 2016-05-09 2016-07-04 Microsoft Excel witheld Enquiries British Geological Survey 0115 936 3143 0115 936 3276 Environmental Science Centre, Nicker Hill, Keyworth NOTTINGHAM NOTTINGHAMSHIRE NG12 5GG United Kingdom enquiries@bgs.ac.uk distributor Enquiries British Geological Survey United Kingdom not available distributor https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#item182409 WWW:DOWNLOAD-1.0-http--download Data download https://doi.org/10.5285/436290d4-a813-4797-bac4-1f8af4af7d78 WWW:LINK-1.0-http--related Citation Information - Digital Object Identifier (DOI) Ougier-Simonin, A., Clarke, A. (2023). Triaxial compressive strength data of tests conducted at elevated temperature on hydrothermalised basalt samples from Osa Peninsula (Costa Rica) and oceanic crust basalt from Cocos Plate. NERC EDS National Geoscience Data Centre. (Dataset). https://doi.org/10.5285/436290d4-a813-4797-bac4-1f8af4af7d78 information dataset 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 This dataset contains raw (clean but not interpreted) triaxial compressive strength data of tests conductive at elevated pressure and temperature as outlined in "Vannucchi, P., Clarke, A., de Montserrat, A., Ougier-Simonin, A., Aldega, L., & Morgan, J. P. (2022). A strength inversion origin for non-volcanic tremor. Nature Communications, 13(1), 2311. https://doi.org/10.1038/s41467-022-29944-8". The data is provided in a .zip folder containing the files of 5 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, axial strain A and B, axial average strain, circumferential extensometer, circumferential strain, volumetric strain, internal temperature, and axial delta P were recorded. Triaxial testing was undertaken using the MTS 815 servo-controlled stiff frame inside a vessel capable of a confining pressure up to 140 MPa at the Rock Mechanics and Physics Laboratory, British Geological Survey, UK. The confining cell is fitted with external heater bands and utilizing utilizes cascade control from internal and external thermocouples (accurate to ± 0.5°C). An initial axial pre-load of 2.3 kN was applied, to ensure a stable contact and alignment of the platens. The confining pressure vessel was then closed and filled with mineral oil confining fluid. The axial pre-load was maintained whilst the confining pressure was applied at 2 MPa/min to 60 or 120 MPa; these values were chosen to approximately bracket the pressures at the up-dip limit of seismic nucleation, corresponding to 2 – 4 km depth (Arroyo et al., 2014). At this point, whilst held in axial force and confining pressure control, the rig was heated at 2°C/min to 60°C to approximate the average temperature conditions at the depth of the up-dip limit of seismic nucleation (Harris and Spinelli, 2010). The samples were then left for approximately 1 hour allowing thermal equilibrium to be reached throughout the confining fluid and the samples. Once stable, axial loading was initiated in constant axial strain rate control at a rate of 5.0 x 10-6 s-1 until macroscopic failure occurred or a significant amount of post peak-stress axial strain was recorded (between 2% and 5%). We note that one test was conducted at the higher temperature of T=120°C with a result within 2.5% of the strength at T=60°C (Table 1). As this is below the expected sample-to-sample variability, no further temperature studies were conducted. The axial load, axial load actuator displacement, axial stress (s1), differential stress (Q=s1 - s3), confining pressure Pc (= s2= s3), confining pressure actuator displacement, axial strain (eax), circumferential strain (ecirc) and temperature were monitored throughout at sampling frequencies of 1s and 0.5kN. File names are: YYYY-MM-DD_LabProjectNumber_SiteName-SampleNumber