Geometry, kinematics and deformation rates along the active normal fault system in the southern Apennines: Implications for fault growth

Abstract

Throw rates, throws and kinematic data have been collected from a localised system of active normal faults in the southern Apennines, Italy, to assess how its growth history differs from that for a distributed fault system in the central Apennines. Both show evidence for fault interaction in that (1) faults located centrally along strike have higher throws and throw rates than distal faults, and (2) cumulative throw and throw-rate profiles summed across strike show central maxima with values decreasing to zero at fault system tips. However, although throw rates increased through time in the central Apennines, we are unable to resolve such changes if they exist for the southern Apennines. Specifically, throw rates derived from offsets of 18 ka geomorphic surfaces are consistent with total throws in the southern Apennines when extrapolated back through time, but overestimate total throws in the central Apennines by a factor of 2.4, suggesting an increase in throw-rate through time for the latter. We discuss why some fault systems appear to have throw rates that are constant through time whilst others accelerate during growth/interaction.