Friday Afternoon Thought Experiment

How about a thought experiment for your Friday afternoon? Tyler Cowen answers "A freak solar event 'sterilizes' the half of the planet (people, animals, etc) facing the sun. What happens?" Cowen's answer: "Putting aside, the 'which half' question, I would predict the collapse of many fiat currencies and the immediate insolvency of most financial institutions. Who could meet all those margin calls? Unemployment would exceed 20 percent and martial law would be declared, food rationing and guys with rifles on street corners." (He goes on for a few more paragraphs.)