Valtakunnallinen seisminen hasardikartta

The project aimed to develop national seismic hazard maps for Finland to support early-stage decision-making for new nuclear facilities (NPPs), with particular relevance to emerging small modular reactor (SMR) deployments, while also providing results applicable to other critical infrastructure projects. Probabilistic seismic hazard assessment (PSHA) was performed using the OpenQuake framework, based on recently published seismic source zoning and the FENCAT21 earthquake catalogue. The NGA-East ground motion prediction equations were applied with a “kappa” correction implemented in Python, based on Random Vibration Theory (RVT). Hazard maps were produced for multiple annual exceedance frequencies (10⁻⁴, 10⁻⁵, 10⁻⁶, 10⁻⁷) at both mean and median confidence levels, covering peak ground acceleration (PGA) and a wide range of spectral accelerations. The results target performance levels relevant for NPPs and SMRs, including operational basis, safe shutdown, and beyond-design basis conditions.

The project was creating maps showing how strong earthquake shaking could be across Finland, to support planning new nuclear facilities, especially small modular reactors (SMRs). We used advanced computer models that simulate possible earthquakes and estimate how often different levels of ground vibrations might occur. These calculations were based on the best available data on earthquakes in Finland and the current scientific understanding of where earthquakes can happen. The maps will help engineers and regulators understand how facilities should be designed and operated to remain safe in case of ground vibration.

Earthquake hazard in Finland is low, but not negligible in case of the design of important facilities like NPPs. Ground shaking depends on how rare the event is, e.g. once in tens of thousands of years earthquakes produce strong ground-shaking, and multiple probability levels were evaluated. The maps show geographical variation of the ground-motion hazards, which is important for site-selection decisions.