| The currently adopted approach to avalanche hazard mapping in northern Italy
includes avalanche dynamic modelling, coupled with statistical analysis of
snow depth at avalanche start. The 30-years and 300-years return period
avalanches at a given site are modelled and their run out zone and pressure
are evaluated. The snow depth in the avalanche release zone is assumed to
coincide with the three days snow fall depth H72 featuring a return
period of 30 years and 300 years, respectively. In the Italian alps only
short series of observed snow depth are available, covering a period of 20
years or so, thus requiring a regional approach, or index value approach for the
purpose of high return period quantile estimation. Based of former studies,
here we apply the index value approach developed for the Lombardia region,
in northern Italy, for hazard mapping in a particular avalanche site. A
dynamic avalanche model is tuned using the runout data for two major
observed avalanche events. Then, the 30-years and 300-years runout zone and
dynamic pressure are calculated. It is then shown that the obtained hazard
maps are more accurate than those obtained using the evaluation of
H72 as deduced from distribution fitting in a single site. |