very carefully at how much risk power plants might face, those near earthquake fault lines. what s happening in japan could be a major wake-up call for us. you hear people, my god, if the big one hits california or something like that. certainly, this is another example of what we have to fear in this country as well. considering nuclear power, that s right. coming up later, the difficulty many americans had getting out of japan after surviving such an ordeal. it s a story told at many u.s. airports all weekend long. people there reconnecting. you can imagine the relief to get home. the lucky few. first, the unfolding nuclear crisis in japan. there has been a second hydrogen explosion at stricken fukushima daiichi nuclear power plant. the japanese authority say radiation levels have exploded and within legal limits, however. diana alvear has the latest. from narita, japan. good morning. reporter: good morning. what happened earlier today is just a sign of how fluid and how
seismic and tsunami-type events. we will look at whatever information we can gain from this event and see if there are changes we need to make to our system. now, at the same time, there are new questions about exactly how the government would handle a nuclear disaster, if such a tragedy were to occur here. in a letter to president obama, congressman ed markey writes, i am concerned that it appears that no agency sees itself as clearly in command of an emergency response in a nuclear disaster. in stark contrast to the scenarios contemplated for oil spills and hurricanes, there is no specificity for emergency coordination and command in place for a response to a nuclear disaster. so we have some of the same plants as japan, some of them are on major earthquake fault lines, and we re not quite sure who s in charge if a disaster hits. that doesn t sound that good. let s find out more, though. with me now is paul gunter, and stephanie cook, the editor of