The Flims rock avalanche: structure and consequences

Abstract The Flims rock avalanche has a gliding surface that cuts down section in limestone sequence and does not follow weak horizon. is parallel to bedding and/or the penetrative Alpine foliation characterized by shape-preferred orientation of calcite grains. Predisposition was governed structural weaknesses form sub-vertical fault zones within solid limestone. Faults controlled lateral scarps avalanche. main body behaved as semi-coherent mass, which preserved original overall structure. internal deformation occurred dynamic fragmentation, distributed rather heterogeneously. Fragmentation starts formation veins consisting comminuted In later stage crosscutting coalesce texture with entirely (“rock flour”) containing angular shattered fragments variable sizes. involvment post-glacial water-saturated substrate contributed long-runout plowed bulldozer-wise at front escaped upward through moving clastic dikes blow-out pipes. Bulldozing raised valley floor more than 100 m and, on margins, entrained pieces flank neighboring, older Tamins deposit. liquefied breached Reichenau thereof valley. now famous tumas Domat/Ems, Felsberg Chur. Lake Ilanz, dammed avalanche, experienced first major outburst shortly after its formation.