the horizontal dimension represents severity. the crises on the left-hand side fall outside the range of normal, rational human behavior. those on the right are more easily understood and can be handled by existing institution (for example, the legal system) or technical knowledge (for example, plant design).
The vertical dimension differentiates between those crises that are caused or influenced by relatively impersonal economic or technical factors, and those caused by human factors such as organization miscommunication, employee sabotage, etc. As the Challenger explosion illustrates, virtually all major crises are caused by a mixture of human and technical elements. The immediate "cause" of the disaster was a faulty O-ring, a poor engineering design that led to a catastrophic technical break. However, the real precipitating cause of the accident was a bureaucratic organization that deliberated blocked repeated warning signals. (These were in the form of memos, which are reproduced at the back of the Report of the President's Commission on the Space Shuttle Challenger Accident.) The signals said in no uncertain terms that unless the O-ring was corrected, a tragedy was virtually guaranteed. A combination of technical/economic and human/social factors will almost always contribute to the final "big crisis" that an organization experiences.