The image
That image is a screenshot of the Wikipedia article entitled "Pass by catastrophe". As of 14:43, 7 May 2015, it reads:
Pass by catastrophe refers to any number of popular urban legends in academia claiming that if some particular catastrophic event occurs, students whose performance could have been affected by the event are automatically awarded passing grades [...]
There are are no references in the article supporting the claim that this is an urban legend, let alone the claim that pass by catastrophe is a policy at any university.
Policy
I've sampled the examination policies of several institutions and have failed to find a "pass by catastrophe" clause in any of them:
Practice
At York University, a strike caused class cancellations, and exams were postponed "into the summer". (York suspends classes, exams and academic activities during strike. Toronto Star. March 2, 2015)
At Harvard, a bomb threat caused exams to be "cancelled, with grading and rescheduling options varying for each course". (Final Exams Cancelled, Postponed, and, In Some Cases, Continued Anyway Amid Bomb Scare. The Harvard Crimson. December 16, 2013)
[Some students] had the option of taking the exam at a rescheduled time this week or at the start of next semester, or not taking the exam at all and accepting their current grade. For its part, LS1a required students in the evacuated Emerson Hall exam sitting to make up their missed exams Monday evening or in early spring.
At York University, a fire caused exams to be postponed. (Exams cancelled, residence evacuated after York U fire. Toronto Star. December 13, 2010.)
The Monday afternoon blaze damaged steam boilers and generators used to heat most campus buildings, so the university was forced to postpone exams and send students to alternate accommodation.