While extreme natural events are rare, their impact to any process plant, nuclear power plant, or storage facility can cause consequences to the environment, to the population, and a company's bottom line which can be severe beyond any previous expectations. One only has to witness the impact of the earthquake and tsunami in Japan on March, 2011. Through the lens of extreme events, this masterclass will focus on the three fundemental questions of risk assessment: what can go wrong; how likely is it; what are the consequences? The basic tools of risk assessment will be explained and how a risk analyst will employ these tools to quantify the societal and financial exposure an extreme event can cause. Many examples in several fields will be given.