The physics related to the radial propagation of seismic waves from the hypocentre (where the fault ruptures) through the Earth's crust, together with data from past earthquakes, allows us to estimate the ground shaking level at a specific location due to an earthquake of a given magnitude.
For the 2015 seismic hazard model, a reference rock model was determined from extensive geophysical measurements at various seismometer sites in Switzerland. The effects of seismic focus, seismic wave propagation and local amplifications were calculated for this purpose. This represents a major advance on the 2004 seismic hazard model and enables the seismic hazard estimate to be calculated for this reference rock while significantly reducing uncertainties in the estimate.