The 9.0-magnitude earthquake that struck Japan is, of course, a highly exceptional event – an event so rare that its probability cannot be well assessed with models based on limited historic data. Events with very low probability but high impact – so-called “tail risks” – have also been at the heart of the financial crisis.
当然，日本本次遭遇的9.0级大地震是一个极为例外的事件——这个事件发生的概率是如此之小，以至于无法用基于有限历史资料的模型来进行全面评估。而这些发生概率极低但又影响极大的事件——即所谓“尾部风险”（tail risks）——也是金融危机的核心问题。