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Landslide models and Dam sites visualised in VR

For multiple landslide and two dam sites in Central Asia and SE Europe we have completed geophysical surveys (partly) complemented by borehole drilling. These data were first processed and then compiled within a 3D geomodel. Here, we present the geophysical results and the 3D geomodels adapted for visualisation in an immersive virtual environment. The geophysical surveys included electrical and seismic profiles and ambient vibration measurements as well as earthquake recordings. The electrical and seismic data were processed as tomographic sections and analysed with the MASW method (analysis of surface waves), the ambient vibrations as horizontal-to-vertical spectral H/V ratios, and the earthquake data mainly in terms of standard spectral ratios. For most sites, we computed the local soft layer thickness from the resonance frequencies revealed by the H/V ratios. Earthquake data allowed us to compute site amplification factors for the more or less thick soft material layer on the slope, or for the dam structure. The 3Dgeomodel was first built on the basis of topographic data, satellite imagery, as well as various electrical resistivity and seismic refraction tomographies. The soft layer thickness information and borehole data were represented in terms of logs in the model (later interpolated to form volumes). The large Rogun dam site studied in Tajikistan is crossed by the Ionakhsh Fault that could be modeled on the basis of the geological inputs and of a lateral resistivity gradient found on one electrical profile along the steep lower slope. Numerical models were computed for the largest landslide sites and for a blast-fill dam in Kygyzstan (for which also piezometric data were available). Earthquake shaking was simulated as most sites are located in seismically active regions.


Hans-Balder Havenith
Liège Université, Belgium
GeoUtrecht 2020