The 2026 seismic hazard model for Finland

Abstract We present seismic hazard maps for Finland, northern Europe, based on the earthquake catalog FENCAT updated until the end of 2021 and a 2025 three-level hierarchical zoning model. Mean horizontal peak ground acceleration (PGA) maps were generated for 10% probability of exceedance (POE) in 50 years using three ground-motion prediction equations (GMPE) separately with a minimum magnitude M min = 4M w : the Next Generation Attenuation for Central and Eastern North America, the ESHM20Craton model, and FennoG16. We also map PGA for 10% and 2% POEs using M min 2M w and the FennoG16 GMPE calibrated down to this magnitude, supplementing conventional Probabilistic Seismic Hazard Analysis. We anticipate that such information could prove useful in planning digital infrastructure and addressing the public concern that small earthquakes pose in urban areas. Lowering M min increases hazard values at 10% POE in 50 years and changes the spatial distribution, as more localized areas of high-frequency ground motion are displayed. We calculate the uniform hazard spectra (UHS) and perform disaggregation analysis for Kolari, northern Finland, at 5 Hz and PGA. We present all maps for reference very hard-rock conditions. The seismic hazard maps show the spatial variation in PGA values in Finland. They quantify and average the available seismicity record. The maxima in the hazard maps coincide well with the observed enhanced seismicity and the higher seismicity rates in northern Finland. Although the mapped PGA values are low on average, short-duration earthquakes may cause minor damage magnified by higher velocities in local soil layers, especially to vulnerable building parts.