Geophysical study and structural modelling of a mass movement in upper Austria

Abstract

In this paper, a typical workflow for the generation of a three dimensional structural model of a mass movement is presented. For the demonstration of this workflow, the mass movement of the Gschliefgraben (Upper Austria) is used as a case study. The Gschliefgraben is situated on the eastern shore of Lake Traunsee, Upper Austria, on the transition of the Northern Calcareous Alps and the Flysch Zone. This mass movement shows various phases of activity since the last glacial period (Würm), with the last huge landslide in November 2007. This landslide is built up as an earthflow system with occasional mudflows and can be cross-bedded with debris flows and torrential sediments. Due to the continuous accumulation of unconsolidated sediments, subaqueous earth slides in the area of the Gschliefgraben can be observed. Multiple seismic reflection and refraction profiles were measured before and after the last huge landslide. In addition, there are numerous wells and several digital elevation models were recorded too. The seismic reflection profiles were interpreted using a seismic stratigraphic approach. These interpretations in combination with information from the refraction profiles, the wells and the digital elevation models were used to generate a high resolution three-dimensional structural model. The focus of this modelling process was on the western part of the mass movement (base of the mass movement). With the help of the interpretation and the three dimensional model, three phases of mass movements prior to the most recent one can be distinguished. © 2012 WIT Press.