A scoring test on probabilistic seismic hazard estimates in Italy

Probabilistic estimates of seismic hazard represent
a basic element for seismic risk reduction strategies and they
are a key element of seismic regulation. Thus, it is important
to select the most effective estimates among the available
ones. An empirical scoring strategy is described here and is
applied to a number of time-independent hazard estimates
available in Italy both at national and regional scale. The
scoring test is based on the comparison of outcomes provided
by available computational models at a number of accelerometric
sites where observations are available for 25 years.
This comparison also allows identifying computational models
that, providing outcomes that are in contrast with observations,
should thus be discarded. The analysis shows that
most of the hazard estimates proposed for Italy are not in
contrast with observations and some computational models
perform significantly better than others do. Furthermore, one
can see that, at least locally, older estimates can perform better
than the most recent ones. Finally, since the same computational
model can perform differently depending on the
region considered and on average return time of concern, no
single model can be considered as the best-performing one.
This implies that, moving along the hazard curve, the most
suitable model should be selected by considering the specific
problem of concern.