The tectonic geomorphology of bedrock scarps on active normal faults in the Italian Apennines mapped using combined ground penetrating radar and terrestrial laser scanning.

摘要

Using combined datasets from ground penetrating radar (GPR) and terrestrial laser scanning (TLS) we document the variety of tectono-geomorphic features that contribute to the morphology of bedrock scarps associated with active extensional faulting in central Italy. Measurement of faulted offsets across such scarps can provide important fault slip-rate data relevant to seismic hazard analysis if ages can be established for offset features. However, interpretation of these offsets is challenging when geomorphic processes as well as fault slip contribute to exhumation of the bedrock during scarp development. Through the integration of surface (TLS) and subsurface (GPR) datasets, we show that the surface expression of three bedrock scarps results from the interaction between footwall incision, hangingwall sedimentation, channel incision and landsliding as well as fault slip and fault linkage. We further illustrate how these processes can be differentiated to identify locations suitable for determining fault slip-rates. The identification of such features has important implications for our understanding of the relationship between bedrock faulting and geomorphic processes, in turn contributing to improved assessment of fault slip-rates in the central Apennines. The use of combined GPR and TLS datasets here has shown that the tectono-geomorphic features of the studied scarps vary greatly over short distances and we emphasise the need for detailed scarp analysis to elucidate the processes responsible for bedrock exhumation before estimating the rates of fault slip over the timescale of scarp formation.