ABSTRACT
Wellington is a city living with significant seismic hazard. Geological and historic records provide evidence for periodic, large magnitude (M>8) seismic events from multiple active faults in the area. Even though the city center is situated on relatively flat ground, vital infrastructure and many dwellings are located on the surrounding hills and at the bottom of steep slopes. In our study we have investigated the seismic stability of one of the deep cut slopes in the area, the Owhiro Bay Quarry, located several kilometers from Wellington. A seismic array, deployed on the site for period of several months, allowed for direct observation of the site effects for weak motion events. This observation was used for calibrating the linear elastic 2D models of the site. Then a parametric study of the slope stability of the calibrated model was carried out, using both synthetic seismograms and real earthquake signals. The study has shown that initiation of a deep-seated, large-magnitude slope failure is highly unlikely. Triggering of relatively smaller slope movements in the upper part of the slope and near the edges of the quarry benches is more likely. The extent of modeled slope failures, however, is strongly dependent on the non-linear behavior of the highly fractured bedrock in the area.
