How does timer fuse on GP bomb survive impact, well enough to trigger a detonation?

GP means General Purpose, a tem I believe is still used for generic air-dropped bombs. Most-if not all-gp bombs in WWII were designed to explode after impact. One of the reasons was so it could , & cause more damage. 22,000# blockbuster "earthquake"bombs also had delayed detonation so they can punch a deeper hole. If dropped from over 20,000', it could potentially be nearly supersonic. An impact like that must be getting close to the point where not normally explosives can explode. My understanding is that a fuse is like a blasting cap on a stick of dynamite that's useful because it's more sensitive to shock than the dynamite. My challenge is this: How does the cap/fuse-which suffers the same impact as the tnt-remain unexploded after such an unimaginable impact? What does it take to explode such a fuse, & how can such a devise still be operative after a 6-700mph impact?