Decreasing uncertainty in seismic hazard estimates in Fennoscandia by use of seismic source modeling

• Main Authors: Jussila, Vilho, Fälth, Billy, Lund, Björn, Saari, Jouni, Voss, Peter H., Puttonen, Jari, Fülöp, Ludovic
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Fennoscandia
• Online Access: https://cris.vtt.fi/en/publications/0d731d8f-b773-457e-afea-9cbddc2a7ce0; https://ats-fns.fi/images/files/ydintekniikka/atsyt_2017_1.pdf

Seismic hazard estimates for Nuclear Power Plants (NPPs) in Finland are based on the probabilistic seismic hazard analysis (PSHA) method. The methodology integrates information from seismic activity levels in areas surrounding the NPP’s with models for the transmission of ground motion from the seismic source (GMPEs). GMPEs are calibrated with observed earthquake ground motions and express the relationship between the expected peak ground motion and the distance from the seismic source. The variability at a given distance can be significant, so it is important to calibrate GMPEs with sufficient data especially from larger magnitude earthquakes relevant for the safety of NPPs. In order to strengthen the reliability of GMPEs used in Finland we propose that synthetic ground motions are generated as surrogates for actual observations. Synthetic data can complement the calibration of the GMPEs in ranges of magnitude and distance where measurement data is missing. In this paper we describe a procedure for generating synthetic ground motions in the vicinity of larger earthquakes. We show the resulting patterns of ground motion and compare them to existing GMPEs. Finally, we show why the new Fennoscandia GMPEs should not be used for seismic hazard assessments before the coming update.