Why bombs trigger such profound fear: Reflections on Austin, by way of Iraq

This month, we saw what happens when an entire city is gripped by fear. In Austin, six bombs — five that detonated and one that was discovered before exploding — killed two people, injured five and instilled a sense of terror across a metropolitan area of two million.

The deaths and injuries are tragic, but given the numbers, how was the series of attacks able to generate so much fear?