[Very Important thread on the Beirut Port explosion]

(1) It is of no secret that today’s explosion occurred due to years of recklessness by the political elites since they knew there were hazardous materials, and took no caution or action whatsoever to prevent any possible risk

(2) I want to address one important perspective. I am not ruling out the fact that today’s accident might have been purposely ignited, yet there is one thing I must mention, so that both sides of the arguments can be presented.

(3) Many people are saying that the container has been there for years and never exploded and they are quite surprised by the timing of the explosion. From a risk analysis pov, the latter sentence isn't realistic since such incidents might occur randomly after years of neglect.

(4) This is what we call in risk analysis “the Swiss cheese model” which suggests that an organisation's defenses against failure are modeled as a series of barriers, represented as slices of cheese. The holes in the slices represent weaknesses in individual parts of the system.

(5) Continually varying in size/position across the slices. The system produces failures when a hole in each slice momentarily aligns, permitting a trajectory of accident opportunity, so that a hazard passes through holes in all of the slices, leading to a failure (Reason, 1990).

(6) See Picture below for a more visual explanation.
Also for a similar example of a similar incident, see the Texas city refinery explosion in 2005.