Office for Nuclear Regulation

ONR Expert Panel on Natural Hazards - Biographies

Alan Gaidan

Professor of Dynamical Meteorology at the University of Leeds

Alan is a senior scientist based in the School of Earth and Environment at the University of Leeds and associated with the UK National Centre for Atmospheric Sciences (NCAS). Cloud and dynamical modelling of the atmosphere are his main research interests.

Recent projects have included Convective and Orographically induced Precipitation and the enhancement of rainfall due to thermal and orographic effects over the Pennines. He has also worked on projects including the Stratocumulus cloud observations and modelling, lightning generation in cumulo-nimbus clouds and a study of atmospheric waves over the Antarctic peninsula and South Georgia.

His work also includes studies on Marine Cloud Brightening i.e. the effects of the albedo of stratocumulus cloud decks on the radiational balance of the earth system and how it affects the warming or cooling of the planet.

He has also been chief editor of the Royal Meteorological Society journal “Atmospheric Science Letters” and External Examiner at the University of East Anglia on Meteorology and Oceanography, external PhD examiner and supervised ~ 9 PhD students. Other National Capability activities for NCAS have included advising the Americas Cup race (2017) for weather forecasts as well as collaborating with groups in the US, China, India and Europe.

He has been a member of ONR’s Meteorological and Flood Hazard Sub-Panel since 2017.

Alice Walker


Alice is a geophysicist specialising in earthquake seismology, seismic monitoring and hazard. She spent over 30 years at the British Geological Survey (BGS) in Edinburgh where she had participated in its Seismology Group. During that time, she managed a 10-nation, cross-border seismicity project in Europe and, for 11 years, led the team of seismologists and technical staff on the BGS National Earthquake and Information Service. The latter provided rapid details of seismic events to its sponsors, local authorities, the media and public, and conducted longer-term analysis and research to improve the service and our understanding of seismic hazard in the UK.

From 1981-1994 she had a particular focus on discriminating natural earthquakes, man-made explosions and sonic booms from the fracking-induced seismic events caused by the Department of Energy’s Hot Dry Rock (HDR) Geothermal project in Cornwall. Through Alice, the BGS acted as an independent arbiter in relations between the HDR project team, and the local authority and the public.

Over these years, she has built an international reputation, which included working with the European Seismological Commission and the International Association of Earthquake Seismology and Physics of the Earth’s Interior.

She’s also participated in a European Space Agency funded project helping to promote and develop applications of a new, high resolution satellite radar technology (PSI), aimed at reducing geohazards and understanding ground deformation processes.

She has been the technical secretary to ONR’s Expert Panel on Natural Hazards for the last nine years.

Robert (Bob) Holdsworth FGS, FGSA

Professor of Structural Geology at Durham University

Bob Holdsworth is currently Professor of Structural Geology at Durham University and has previously served as Head of the Department of Earth Sciences and Director of Research at Durham University.

An expert on the regional geology and geological evolution of the British Isles, he has also carried out research in continental deformation zones all over the world. His studies of structures such as the San Andreas and Great Glen fault zones have demonstrated the importance of fluid-assisted weakening mechanisms in facilitating repeated periods of reactivation over a wide range of timescales.

He established the Durham Rock Mechanics Laboratory, carrying out novel rock deformation experiments to simulate dynamic weakening processes during earthquakes along faults. He led a group that pioneered the development of digital geological data acquisition and, with his company Geospatial Research Ltd, captured surface rupturing of the 2016 Mt Vettore earthquake (Italy) in near real time.

He has received a number of awards, including the Aberconway (2006) and Coke (2018) medals from the Geological Society of London. 

Bob has been a panel member since it was established in 2011.

Dr Julian J Bommer

Director, Bommer Consulting Ltd, and Senior Research Investigator, Civil & Environmental Engineering at Imperial College London

Julian has been a member of the Seismic Hazards sub-panel since its inception in 2010. A Chartered Civil Engineer and Fellow of the Institution of Civil Engineers, Julian was formerly a Professor of Earthquake Risk Assessment at Imperial College London, where he now holds the position of Senior Research Investigator.

He has published extensively on topics related to ground motion, seismic hazard analysis and earthquake risk assessment in relation to both natural and induced seismicity. He is a past Chairman of the Society for Earthquake and Civil Engineering Dynamics.

Julian has served as a consultant on seismic hazard studies for nuclear facilities in Brazil, Romania, South Africa, Spain, Switzerland, the UAE and the US (California, Idaho, Nevada and Washington). He has also contributed to guidelines on the Senior Seismic Hazard Analysis Committee (SSHAC) process for conducting such studies developed by the US Nuclear Regulatory Commission. He has worked on seismic studies for major dams, bridges, and pipelines worldwide, and served as a member of the Seismic Advisory Board for the Panama Canal expansion.

His portfolio also includes risk assessments related to induced earthquakes in Europe and the Americas, as well as serving as an advisor to the UK Oil and Gas Authority on fracking-induced seismicity.

Ian Main FRSE

Professor of Seismology and Rock Physics at the University of Edinburgh

As well as his current role at the University of Edinburgh, Ian has served as Head of the School of Geosciences Institute of Earth and Planetary Sciences and as Director of Research. 

He is currently a member of the Scottish Regional Advisory Group for Enhanced Learning and Research for Humanitarian Assistance, and the Research Advisory Forum of the Scottish Energy Technology Partnership.

Ian has provided independent advice on induced seismicity in the Netherlands and on the decommissioning of the Brent hydrocarbon field. He moderated the Nature Website debate on earthquake prediction in 1999. He also served as a member of the International Commission on earthquake forecasting for civil protection, following the destructive earthquake in L’Aquila, Italy in 2009.  

He’s received a number of awards, including the 1997 Bullerwell lecture in Geophysics, the 2014 Louis Néel Medal of the European Union of Geosciences, and the 2019 Ed Lorenz lecture in Non-linear Geophysics of the American Geophysical Union. 

He has been a member of the panel since 2015.

Dr Jean Savy

Independent Consultant in seismic hazard and risk

Jean is a recognised expert in the use of probabilistic techniques for the characterisation of risk in critical facilities. His team at Lawrence Livermore National Laboratory (LLNL) developed the method used by the Nuclear Regulatory Commission (NRC) to review the siting of all nuclear plants in the US. Early on, he worked on methods of integration of experts’ knowledge to assess epistemic uncertainty in probabilistic seismic hazard analyses (PSHA), and he contributed to the elaboration of the Senior Seismic Hazard Analysis Committee report, now the standard process for all high-level PSHA.

At LLNL, Jean’s expertise has been used in many seismic, wind and flood hazard studies and probabilistic risk analyses for critical facilities, including on the US, countries of the former Soviet Union, Caucasus and Central Asia, and in Korea.

He has worked on International Atomic Energy Agency missions as a subject expert.  Jean has also served as chair of several American Nuclear Society working groups to develop design and operation standards for the nuclear industry.

Jean studied in France, and the US, where he obtained a PhD at Stanford University, prior to joining Massachusetts Institute of Technology as a research professor, and LLNL. A subsequent position at Risk Management Solutions Inc. allowed him to apply his knowledge to the insurance, re-insurance and financial industry. He also works as a consultant for Lawrence Berkeley National Lab.

Jean has been a panel member since 2011.

Paul Sayers

Partner at Sayers and Partners

Paul is a partner at the applied research consultancy Sayers and Partners. He is a recognised expert in flood and coastal risks (at local and regional scales), coastal processes, the performance of coastal defences and the development of adaptation strategies. 

Previously a Board Director at HR Wallingford, Paul has over 25 years experience in all aspects of flood and coastal management. He gained this experience working in the UK (extensively with the Environment Agency, local authorities, private infrastructure providers and NGOs) and internationally, including collaborations in Australia, China, Canada, Denmark, Norway, Italy, Netherlands, Nigeria, and the USA.   

In addition to Paul’s applied research consultancy activities he continues to contribute to leading international academic research groups at the University of East Anglian (the Tyndall Centre) and TU Delft/IHE in the Netherlands (focusing on flood and coastal issues).  

Paul is also an advisor to the Joint Defra/Environment Research Programme (on flood and coastal Asset Management) and a member of the Editorial Board for the Journal of Flood Risk Management.

Paul has been a panel member since 2020.

Stephan Harrison

Professor of Climate and Environmental Change, University of Exeter, UK

Stephan is a climate scientist, specialising in climate change impacts. Since 2011 he has advised the ONR on the impact of climate change for UK nuclear power sites. He also sat on the Seismic Risk Committee. 

Stephan is Director and founder of Climate Change Risk Management which since 2003 has provided detailed scientific advice to governments, commercial organisations and NGOs around the world. 

Stephan has a PhD in Quaternary Science (geomorphological responses to past climate change) and his research focuses on climate change impacts at a range of spatial and temporal scales. He has over 30 years’ post-doctoral research experience working in the world’s mountain regions.

He was a Co-Investigator on the HELIX Programme (High End Climate Change and Extremes; 2013-2017) funded by the EU to assist decision-makers and the research community to adapt to future climate change. His role was to provide the detailed assessments of water supply variations in the Hindu-Kush-Himalaya region. Stephan was also Co-Investigator on a Natural Environment Research Council (NERC) funded project looking at climate change-driven natural hazards in Chile (2015-2018) and is Principal Investigator on a NERC project researching climate change impacts in Peru (2019-2022).  

He has published over 150 papers in the peer-reviewed scientific literature.