| During the winters of 1999 and 2000
large avalanches occurred in the ski resort of Las Leñas (Los Andes,
Mendoza, Argentina). On 8 September 1999 an avalanche of new, dry snow ran
over a path with a 1000 m vertical drop. On 30 June and on 1 July 2000
five avalanches of similar vertical drop, which start with new snow,
entrained very wet snow during their descent, and evolved into dense snow
avalanches.
To use the MN2D dynamics model correctly, calibration of
model parameters is necessary. Also, no previous works with the use of
dynamics models exist in South America. The events used to calibrate the
model occurred during the winters of 1999 and 2000 and are a good sample
of the kind of avalanches which can occur in this area of the Andes
range.
By considering the slope morphology and topography, the
snow and meteorological conditions and the results of the model
simulations, it was estimated that these avalanches were not extreme
events with a return period greater than one hundred years. This implies
that, in natural conditions, bigger, extreme avalanches could
happen.
In this work, the MN2D dynamics model is calibrated with
two different avalanches of the same magnitude: dry and wet. The
importance of the topographic data in the simulation is evaluated. It is
concluded that MN2D dynamics model can be used to simulate dry extreme
avalanches in Argentinean Andes but not to simulate extreme wet
avalanches, which are much more sensitive to the topography. |