Fault Tree Analysis (FTA) is a method for discovering the root causes of failures or potential failures. FTA is a top-down approach that helps you understand how to fix or prevent a failure.
FTA starts with a top-level event like a service outage. Then one goes down to detailing all the contributing faults and the causes of faults for that failure. You use the resulting FTA diagram to establish countermeasures to eliminate the causes of the outage.
This can be used for Availability and Continuity activities in search of what can go wrong with the IT infrastructure. Thus it may help isolating weak spots on the infrastructure which in turn enables countermeasures identification and implementation.