Third explosion but the second explosion is the most concerning as it creative a plume of radioactive material. The USS Ronald Reagan is on station and has been modeling the plume. The cloud could eventually contaminate parts of the United States and Canada. The amount of radiation may be minute or it could be large in the event of more damage to the reactors. Japan had insured their buildings and infrastructures could withstand earthquakes but what even the Japanese could not have predicted was the effect of earthquake, followed by tsunami/flooding and nuclear fallout. The damage to the Japanese infrastructure is hampering efforts to control the meltdown. We probably don't want to think about what this will do to the seafood from the North Pacific.