Fig. 1

(A) Location of the Hebgen Lake Fault, Red Canyon Fault in Western Montana and other normal faults, the S31 Creek bedrock fault scarp, and 1959 main shock focal mechanism²⁵. (B) Central section of bedrock fault scarp along Highway 278 including the 1959 fault mirror below the red dash line and degraded fault scarp resulting from historic ruptures between the blue and red dash lines; GPS coordinates: 44.834° N, 248.723° E, 2027 m asl (black star on (A)). Details on historic fault degradation are in²⁸. The fault plane strikes N120° E, dips ~ 66° S and cuts through Cambrian Meagher Limestone. The hanging wall is either not exposed or covered with scree. (C) Conceptual block diagram of the Hebgen Lake Fault showing fault mirror and damage zone in the Meagher Limestone. (D) Detail of the fault structure with four juxtaposed zones including the undeformed carbonate (D), the damage zone (C), the goethite botryoidal deposits (B) and the fault mirrors (A). The Figure was created using Adobe Illustrator v.29.0 and Arc-GIS Pro v.3.2.