Normally disasters have very negative impact over national currency of a certain country. The higher the disaster is, more negative impact will have to national currency.
For instance, strong earthquake in Japan at the end of July 2007. It had very negative impact over Japan’s economic, especially over automotive industry – the second largest economy in the world. After the quake companies Toyota, Nissan, Suzuki, Mitsubishi and Honda announced that the stop production of some of their models , because of factory damages. The largest nuclear power plants in the world – Tokyo Electric Power, announced that shut down for unknown period of time. All of that automatically contribute for drop of main index in Japan – Nikkei-223, which lead to decreasing of Yen’s strength. You all know what happened on 11 march 2011, and what was the impact.