Beyond the devastating and saddening human costs, the earthquake in Japan is another reminder of the complexity of the world’s supply chains and the great interdependencies in global production systems. The world’s supply chains are complex and highly optimized to deliver products efficiently at the lowest cost. They are characterized by a sequential mode of production where goods are produced in a series of stages in different countries by vertical specialists who pass them across borders to the next firm in the value chain. Shocks like this ripple through the chain, and test the robustness of their design. With lean inventories and just in time deliveries, there is not a lot of slack in the system to act as a buffer. This disaster promises to be quite a test.