The objective of this page is to enable users to examine the dependency of the results of probabilistic seismic hazard analysis (PSHA) on various input parameters

To quantify PSHA at a site, you have to calculate the frequency of exceedance of different levels of ground motions (GMs) at the site to formulate the hazard probabilistically

The input parameters for GM calculations are:

Earthquake’s magnitude, rupture mechanisms, rupture width and dipping angle, and shallow soil conditions

The ground motion prediction equations (GMPEs) statistically estimate different levels of ground motions for different tectonic regimes, given the source and site parameters

The rates of exceedance of GMs are quantified by the expected annual frequency occurrence of the earthquake, defined here as the recurrence interval

Using this info, PSHA estimates the probability of exceedance for different user-defined GM levels

• Rupture Dipping Angle: It impacts the hanging wall effects on GM values. Sites within the hanging wall area typically experience higher levels of GMs compared to those on the footwall.
• Rupture Mechanisms: Recent GMPEs estimate very similar GMs for earthquakes with strike-slip and reverse/thrust mechanisms. Earthquakes with normal faulting mechanisms tend to produce lower levels of GMs compared with those of strike-slip and reverse/thrust mechanisms.
• Notice how different GMPEs treat the impacts of hanging wall, i.e. dipping angle, on GMs estimates