To achieve certification the engine must pass a 'blade off' test. The engine casing immediately surrounding the fan must be capable of containing the rogue blade. Kevlar is used on some. In the pictures above of this incident, the fan case is intact (or at least looks so). The fan inlet cowl however is severly damaged and largely missing. It is not designed to withstand a thrown fan blade.
You tube has a few videos of engine blade off tests.
