Considering that my office overlooks Ground Xero, and DW works near Times Square, getting insdie when the mushroom cloud appears may not be an option. We just may not be able to run that fast. If you can feel the heat, you are probably within range of a shockwave. Do not run, unless you are real close, get down, find cover, NOW, and wait for two waves. Shockwaves will come in and go out. If you are this close, you are in a tough situation, but what else can you do?