The initial speed of shock waves (I believe shock waves slow down over time/distance traveled) generated by explosives is complicated and somewhat based on the detonation velocity of the particular explosive involved (way to complicated for my old ass to remember/figure out).
Here's a couple examples (relative effectiveness is based on a TNT equivalent = 1.0):
- Ammonia Nitrate (fert grade), detonation velocity 2,700 m/s, relative effectiveness .42;
- ANFO (explosive grade), detonation velocity 5,270 m/s, relative effectiveness .74;
- TNT, detonation velocity 6,900 m/s, relative effectiveness 1.0;
- C-4, detonation velocity 8,040 m/s, relative effectiveness 1.37;
Some basics; If you're a good distance away from a large detonation but still within the hazard zone/footprint - typically the first thing to hit your location will be earth shock, followed shortly by the shock wave/boom - plus some frag. If you're really close to ground zero, everything happens so fast you won't remember what hit you first.