The upgraded full-scale avalanche test-site Ryggfonn, Norway

Measurements of full-scale avalanches are expensive and time con- suming, but are indispensable to gain in-depth understanding of the flow behavior of avalanches. They are needed to crosscheck the scaling used in small-scale experi- ments and also form the basis for developing and calibrating numerical models. The recent partial upgrade of NGI's Ryggfonn test-site is focused on the processes occurring during interaction between avalanches and a catching dam in the runout zone. These processes are crucial for the efficiency of this type of avalanche mitigation measure, which has been the focus of several small-scale experiments in recent years. But qualitatively and quantitatively good observations from real avalanches for a cross- comparison are rare. Therefore, two new masts were constructed at Ryggfonn. One is located about 10 m upstream of the foot of a catching dam and has a height of 15 m. The other stands on the crown of the dam and is 6 m high. In this way, we also hope to complement the SLF full-scale tests at the Vall ´