The fact that a disaster of a particular type has not occurred recently or even within human memory (or even ever) is a bad reason to ignore it. The risk may be slight, but if the consequences should it materialize are great enough, the expected cost of disaster may be sufficient to warrant defensive measures.
某种特定的灾难最近、或者在人类记忆中（或者从来）没有发生的事实是忽略它的糟糕的理由。风险可能是轻微的，但是可能造成的后果是巨大的，可以预期的灾难成本应当足以建立防护性措施。