Geodata for Seismic Hazard Assessments

Abstract

This paper describes the types of additional geodata, which can be used to supplement ‘standard’ data sets relating to landslides; these additional data enable more precise assessments of the landslide hazard and the associated potential risk. Importantly, this research has investigated the resonant response of landslide masses to a range of seismically generated wave spectra impact (that is, ground vibrations with different amplitude and frequency). The study included observing the impact of low frequency vibrations from distant earthquakes on landslip masses and the plastic strains of slopes subject to microseisms and micro earthquakes. An analysis of landslide mass transport by means of correlating start heights to strains distances ratios, was undertaken using a conceptual ‘drop model’. This analysis also showed the intensity of seismicity needed to ‘trigger’ or initiate a landslip mass. The results from these analyses are in a qualitative agreement with the field observations made in some seismically active regions. The calculations used, employ ‘frames’ of the round cylinder method; this enables estimates of landslide stability, information that greatly facilitates landslide hazard assessment. Having an indication of the probability of a landslide (at any stage of formation up until the actual slide), as well as knowledge about the slide mass, mass transport, slope contours, the area likely to be affected, the Froude number and the likelihood of secondary phenomena such as floods and mudflows enables a more complete assessment of the landslide hazard and greatly assists design and engineered risk reduction measures.