Rock quality assessment with reflection seismic techniques: a case history in the Appenines

A high resolution P-wave seismic reflection survey was recently carried out in the Apennine area of the Reggio Emilia Province (North-Italy) on an active rock landslide. The objectives of the experiment were: investigate structure and stratigraphy of the bedrock deposits and landslide body, develop a data processing strategy to study the rock quality and testing the feasibility of a seismic monitoring of the landslide evolution. The first part of the experiment was successfully completed. The bedrock and landslide body structures were clearly imaged by seismic reflections in the stacked section. The seismic image also exhibits some low reflectivity zones, initially interpreted as faults or structural weaknesses. Because of the extreme importance of discontinuity surfaces, in a landslide context, the low reflectivity zones were analysed and studied in terms of waveform response. A specific data processing was designed to preserve seismic amplitudes and to estimate bedrock physical parameters through wave character analysis. The reflection seismic survey focused on the estimation and evolution of structural weaknesses, using waveform analysis, could be a landslide monitoring technique. An accurate study of time-reflectivity response is proposed as. an alternative to an extensive use of geotechnical and geomechanical measurements on active landslides.