Here’s a haunting Gmaps hack: “The High Yield Detonation Effects simulator maps overpressure radii generated by a ground-level detonation; these radii are an indicator of structural damage to buildings. No other effects, such as thermal damage or fallout levels, are included in this tool. Note that the displayed rings are “idealized”; that is, no account is taken of terrain, urban density, ground type, weather conditions, and so on.”
(Thanks, Eric!)