Integration of large deep-seated, creeping mass movements in a regional hazard map - an approach to determinate it's probability of occurrence

In the last two decades hazard maps (HM) have established as one of the major tools for risk assessment and urban planning in alpine regions. During this time, various efforts and methodical adjustments could be recognized that significantly supported reliability and applicability of HM. All those adjustments are based upon the fundamental Swiss system of geological hazard assessment and mitigation, the so called BUWAL, which is by now considered to be the main fundament for the elaboration of HM in alpine areas. One of the last problems that can be regarded as almost unsolved in terms of a local hazard zoning and elaboration of HM is the integration of large deep-seated and creeping mass movements (i.e. Talzuschub, Sackung) in these maps. The classification of hazard zones that are to be depicted by the HM according to BUWAL requires the assessment of "intensity" and "probability of occurrence" as basic information. But since intensity appears to be irrelevant for the classification of those phenomena (intensity is only determined by velocity [rate] as moving rock mass [volumina] and depth of surface of rupture always correspond to a "high"-grade intensity) and thus probability of occurrence is the main parameter for classification respective the BUWAL matrix, it becomes obvious, that existing methods have to be completed by different approaches. Sound research, published in various papers during the last decades, showed that almost every slope movement takes place in correspondence to the theories of "accelerating creep", no matter if one regards falls, topples, slides or a spreads in bedrock or soils. Thus, the application of mathematically based con-cepts of creep theory in combination with suitable codes of numerical modelling and targeted monitoring systems as fundament for data collection in addition to intensive geological field works seems to be such a different and promising approach for integrating large deep-seated and creeping mass movements in a regional HM. This article introduces the research project "Talzuschub Algund" that makes use of this multi-based concept, also discussing requirements, chances and constraints of the accelerating-creep-theories for elaboration of HM and time related forecasts/predictions in the sense of the BUWAL-matrix. The project was established in 2007 by the Office for Geology and Building Material Testing of the Autonomous Province of Bolzano in close cooperation with the Chair for Engineering Geology of the Technische Universität München.