Surface ruptures from the November 3, 2002, M7.9 earthquake occurred on the Denali fault and at least two other connected faults that have a combined rupture length of about 320 km. The Susitna Glacier fault (SGF), a newly discovered fault, forms the westernmost 49 km of the surface rupture. Analyses of teleseismic data indicate that the initial phase of rupture for the earthquake involved
... [Show full abstract] thrusting on NE-SW oriented nodal planes. Field observations of south-directed-thrust surface rupture along the SGF are consistent with the initial fault motions. Discovery of the SGF demonstrates that strike-slip displacement on the Denali fault may be accommodated by thrust faults to the south, and that strike-slip rupture may terminate at such thrusts. The SGF is expressed as an east-trending scarp or scarps on glacial till and colluvium, from west of the West Fork valley eastward along the base of unnamed hills that form the northern margin of Monahan Flat. The ruptures continue northeastward as nearly planer fractures across the lower part of the Susitna Glacier before intersecting the Denali fault beneath the glacier at about 63.52°N, 146.975 W (Healy 1:250,000 quad.). The ruptures, which have a sinuous trace that is typical of thrust faults, indicate that the SGF dips about 25-30º NNW in the shallow subsurface. The morphology of the thrust scarps vary greatly depending on the width of the deformation zone, the amount of folding and warping, the number of adjacent strands, and the type of material that was faulted. Surface ruptures are present on glacial ice, till, and slope colluvium that is covered by tundra. The zone of deformation varies in width from a few meters to tens of meters, and scarps range in height from
