Okay, so I just started watching #Foundation, and I have some questions...

1) How the hell did the empire not detect the explosives used to destroy the star bridge? More importantly, if they were unable to detect these explosives, how has this not happened sooner?

2) When the star bridge collapsed, they said it "wrapped around the planet like a garrote cutting through 50 levels", killing 100 million. Earth has one level, and a structure like that collapsing and wrapping around our planet like a garrote would easily kill more than 100 million. How was the casualty count that low for a planet so densely-populated that it needs 50+ surface levels?