Probabilistic life-cycle assessment of landslides exposed to both rainfall under nonstationary climate change effects and earthquakes

Combined effects of rainfall and seismic hazards pose significant threats to structures and infrastructure systems. Additionally, climate change is projected to impact the intensity and frequency of future rainfall, increasing the likelihood of landslides. However, evaluating long-term landslide probability under the combined effects of rainfall and seismic hazards, while considering nonstationary climate change, presents significant challenges due to the distinct characteristics of their occurrence processes. This study introduces a novel framework for probabilistic life-cycle landslide assessment that systematically integrates climate change effects on rainfall hazard along with seismic hazard. Probabilistic nonstationary rainfall and seismic hazard models are developed by leveraging stochastic renewal process theory based on occurrence probability and the associated hazard intensity distribution. Slope fragility assessments are conducted for four event scenarios: individual rainfall, individual earthquake, rainfall followed by an earthquake, and an earthquake followed by rainfall, using seepage and equivalent linear analysis through Monte Carlo simulation. Finally, using the total probability theorem, life-cycle landslide probability is numerically evaluated by convolving nonstationary rainfall and seismic hazards with slope fragilities. An illustrative example is provided by applying the proposed framework to a slope in Hiroshima city, Japan, to explore how the combined effects between nonstationary rainfall and seismic hazards impact life-cycle landslide probability.