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National Seismic Hazard Maps for the UK: 2020 Update

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National Seismic Hazard Maps for the UK: 2020 Update National seismic hazard maps for the UK: 2020 update Multi Hazards and Resilience Open Report OR/20/053 BRITISH GEOLOGICAL SURVEY MULTI HAZARDS AND RESILIENCE PROGRAMME OPEN REPORT OR/20/053 Keywords National seismic hazard maps Seismic hazard, UK, earthquake catalogue, ground motion. for the UK: 2020 update Bibliographical reference MOSCA, I, S SARGEANT, S, BAPTIE, B, MUSSON, RMW AND I Mosca, S Sargeant, B Baptie, RMW Musson and T Pharaoh PHARAOH, T 2020. National seismic hazard maps for the UK: 2020 update. British Geological Survey Open Report, OR/20/053. 138pp. Copyright in materials derived from the British Geological Survey’s work is owned by UK Research and Innovation (UKRI) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining permission. Contact the BGS Intellectual Property Rights Section, British Geological Survey, Keyworth, e-mail [email protected]. You may quote extracts of a reasonable length without prior permission, provided a full acknowledgement is given of the source of the extract. © UKRI 2020. All rights reserved Keyworth, Nottingham British Geological Survey 2020 BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS British Geological Survey offices shops at Nottingham, Edinburgh, London and Cardiff (Welsh publications only) see contact details below or Nicker Hill, Keyworth, shop online at www.geologyshop.com Nottingham NG12 5GG The London Information Office also maintains a reference Tel 0115 936 3100 collection of BGS publications, including maps, for consultation. BGS Central Enquiries Desk We publish an annual catalogue of our maps and other Tel 0115 936 3143 publications; this catalogue is available online or from email [email protected] any of the BGS shops. BGS Sales The British Geological Survey carries out the geological survey of Great Britain and Northern Ireland (the latter as Tel 0115 936 3241 an agency service for the government of Northern Ireland), email [email protected] and of the surrounding continental shelf, as well as basic research projects. It also undertakes programmes of The Lyell Centre, Research Avenue South, technical aid in geology in developing countries. Edinburgh EH14 4AP Tel 0131 667 1000 The British Geological Survey is a component body of email [email protected] UK Research and Innovation. Natural History Museum, Cromwell Road, London SW7 5BD Tel 020 7589 4090 Tel 020 7942 5344/45 email [email protected] Cardiff University, Main Building, Park Place, Cardiff CF10 3AT Tel 029 2167 4280 Maclean Building, Crowmarsh Gifford, Wallingford OX10 8BB Tel 01491 838800 Geological Survey of Northern Ireland, Department of Enterprise, Trade & Investment, Dundonald House, Upper Newtownards Road, Ballymiscaw, Belfast, BT4 3SB Tel 01232 666595 www.bgs.ac.uk/gsni/ Natural Environment Research Council, Polaris House, North Star Avenue, Swindon SN2 1EU Tel 01793 411500 Fax 01793 411501 www.nerc.ac.uk UK Research and Innovation, Polaris House, Swindon SN2 1FL Tel 01793 444000 www.ukri.org Website www.bgs.ac.uk Shop online at www.geologyshop.com Foreword This report is the published product of a study by the British Geological Survey (BGS) to update the national seismic hazard maps for the UK. This is to take account of advances in seismic hazard methodology since the last seismic hazard maps were developed by Musson and Sargeant (2007) and present the results in a format that will be compatible with the future Eurocode 8 revisions. Acknowledgements This work has benefitted from the knowledge and experience of a large number of people. We are very grateful to the experts who have been supporting this work: Guillermo Aldama-Bustos, John Douglas, Ben Edwards, Peter Stafford, Fleur Strasser and Iain Tromans. We are also very grateful for the support and input of the members of the BSI National Committee B/525/8 Structures in Seismic Regions and Edmund Booth, Ziggy Lubkowski and Tim Allmark in particular, and members of the ONR Review Panel for their helpful reviews of an earlier draft of the report. From BGS, we thank Davie Galloway for his assistance in developing and checking the earthquake catalogue, and Margarita Segou for useful discussions on the catalogue analysis. Maarten Krabbendam and Graham Leslie have provided guidance on matters relating to the seismotectonics of the UK, and we are grateful to Richard Luckett, Margarita Segou, Ciaran Beggan, Ekbal Hussain and David Kerridge for internally reviewing the report. This work is supported by the British Geological Survey and the Institution of Civil Engineers. i Contents Foreword .......................................................................................................................................... i Acknowledgements .......................................................................................................................... i Contents .......................................................................................................................................... ii List of abbreviations ...................................................................................................................... viii Summary ........................................................................................................................................ xi 1 Introduction ............................................................................................................................... 1 1.1 Project implementation ................................................................................................... 1 1.2 Key modifications with respect to MS07 ........................................................................ 2 2 Methodology ............................................................................................................................. 3 3 Earthquake catalogue .............................................................................................................. 7 3.1 Data Sources .................................................................................................................. 7 3.2 Catalogue Analysis ....................................................................................................... 10 4 Tectonics and seismicity of the British Isles .......................................................................... 16 4.1 Crustal Structure and Faulting...................................................................................... 17 4.2 Seismotectonics ............................................................................................................ 19 4.3 Seismicity of the British Isles ........................................................................................ 23 5 Seismic source characterisation ............................................................................................ 29 5.1 Geometry of the source model ..................................................................................... 30 5.2 Maximum magnitude .................................................................................................... 35 5.3 Recurrence statistics .................................................................................................... 36 5.4 Depth distribution .......................................................................................................... 44 5.5 Faulting ......................................................................................................................... 44 6 Ground motion characterisation model .................................................................................. 44 6.1 Comparison with UK ground motion observations ....................................................... 49 6.2 Soil conditions ............................................................................................................... 53 6.3 Vs-κ0 adjustment ........................................................................................................... 53 7 Hazard calculations ................................................................................................................ 63 7.1 Minimum magnitude ..................................................................................................... 63 7.2 Sensitivity Analysis ....................................................................................................... 63 7.3 Hazard maps ................................................................................................................ 68 7.4 Results for example sites ............................................................................................. 68 8 Discussion .............................................................................................................................. 77 8.1 Comparison with previous studies ............................................................................... 77 8.2 Limitations of the present study.................................................................................... 81 9 Conclusions ............................................................................................................................ 85 References ...................................................................................................................................... 1 Appendix 1 ....................................................................................................................................... 9 ii Appendix 2 Hazard
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