he 2026 offshore and onshore seismic hazard maps cover the UK, the Channel Islands, and the UK offshore Exclusive Economic Zone EEZ (UK commercial waters). The data comprises a grid of 4663 points that are spaced 0.125° in latitude and 0.25° in longitude, and is developed for an additional ground motion parameter, spectral acceleration at 0.15 s. Therefore, the 2026 hazard maps are for four ground motion parameters, i.e. peak ground acceleration (PGA), spectral acceleration at 0.15 s (SA0.15 s), 0.2 s (SA0.2 s) and 1.0 s (SA1.0 s), for 5% damping and rock conditions and five return periods, i.e. 95, 475, 1100, 2475, and 5000 years. The report of Mosca (2026) describes these updated maps in detail, whereas the technical report by Mosca et al. (2024) provides a detailed description of the methods (see also http://www.earthquakes.bgs.ac.uk/hazard/UKhazard.html). The input data to compute the maps are in in Mosca et al. (2025; DOI: https://doi.org/10.5285/a6babafa-5c82-4e76-aef5-27441104187f). The map for spectral acceleration at 0.15 s has been used to calibrate the seismic design requirements in the second-generation Eurocode 8 to the hazard levels of the UK and will be cited in the British Standards UK National Annex and PD6698.
