Fig. 1

Lake Lauerz and its catchment. The dotted line indicates the North-Alpine nappe front, which broadly separates the Helvetic Nappes in the southeast from the Subalpine Molasse in the northwest. Gnipen and Wildspitz are the two main summits of the Rossberg chain. The limits of four major rockfall bodies are outlined with bold lines (after Gasser 2003). Locations referred in the text are indicated with tokens: SA Steiner Aa, SÄ Sägel, BU Buosigen, WE Weidstein, BW Blattiswald. Topographic map and digital elevation model by swisstopo