Dear Oscar,
The Sigma 0 checkbox is used in those cases where the PSHA calculation is carried out with a sigma 0.0 GMPEs. As you know, the GMPEs are treated as random variable with a mean and a standard deviation. If the Sigma 0 is checked, that probability distribution will have sigma 0.0.
If you desire to run a "no truncated" model, the Sigma 0 has to be unchecked this reffers to a different concept.
Thank you for your preference and interest in R-CRISIS.
Best regards,
Dear Shweta,
In the R-CRISIS Help Menu -> Basic theoretical background, you will find a brief description of the hazard computation algorithm used by R-CRISIS. Equation 7, presented below, is the one used by R-CRISIS to compute seismic hazard for situations in which the sources are spatially distributed (k=1,…,N), there are earthquakes of various magnitudes (Mi, i=1,…Nm) and the earthquake occurrence probabilities in known time frames Tj at source k are given by Pk(s,Mi,Tj), that is, the probability of having s events of magnitude Mi in the next Tj years at source k.
As may you see, the calculation depends of probabilities, values contained in the .nps file which describes a Generalized Non-Poissonian model.
Thank you for your preference and interest in R-CRISIS.
Best regards,
