A mega‐thrust subduction earthquake triggers a sequence of cascading hazards. A recent example of such catastrophes is the 2011 Tohoku earthquake; ground shaking caused major damage to infrastructure, while massive tsunami washed out numerous people and houses. Nonetheless, existing risk assessment frameworks do not address the multi‐hazards nature of earthquake‐related damage adequately. The project aims to tackle the challenging problem of developing an integrated methodology for assessing ground shaking and tsunami. The investigation is focused upon the 2011 Tohoku earthquake, as the event offers extensive datasets for strong motion observations and tsunami inundation/run‐up survey results which will be extremely useful for validation. A unique aspect of this project is to evaluate the impact of uncertain earthquake slips on strong motion and tsunami inundation simultaneously and probabilistically. Moreover, rigorous sensitivity analysis will be conducted to quantify the uncertainty of predictions for future scenarios. With the developed tool, one can evaluate a complete history of external loading to buildings due to ground acceleration and tsunami flows, rather than two hazard estimates from separately derived shaking and tsunami inundation maps. Importantly, this promotes more comprehensive integrated risk assessment and quantification of uncertainty in hazard predictions. The benefit from this project can go beyond the research outcomes, having potential impact on the way how hazard assessment and natural disaster management are conducted in practice.