Seismotectonics of the Amenthes Rupes thrust fault population, Mars

Abstract

Thrust faults within the Amenthes Rupes population in eastern Mars accommodated contractional strains of ∼0.06% with total cumulative moment (energy) release of ∼2 × 1024 MJ during Late Noachian time. "Small" faults, that scale three-dimensionally, accommodate only 12-17% of the strain and 6-9% of the moment release, indicating that inventories of Martian faults need not be complete down to the smallest lengths for meaningful estimates of strain and moment to be obtained. Frictional stability relations for Martian lithosphere suggest that most (83%) of the largest fault, Amenthes Rupes, was seismogenic during displacement accumulation, with smaller faults being progressively less seismogenic as shallower depths are penetrated with decreasing fault lengths. Given plausible displacement rates from terrestrial intraplate thrust faults of ∼1-0.01 mm yr-1, the Amenthes fault population may have taken as little as 1.5 m.y. to grow into its present configuration, corresponding to slow homogeneous strain rates of 10-17 s-1, or less, that are comparable to those of terrestrial plate interiors.