As a general rule of thumb, a person will begin to feel blast vibrations at levels as low as 0.02 in/s. Johnson County enforces a maximum ground vibration (PPV) of 1.0 in/s from 0 ft. – 5,000 ft. from the blast and 0.75 in/s for property greater than 5,001 ft. from the blast. Blasters have to keep their shots below those maximum ground vibration levels. As a comparison, slamming a door may send ground vibration up to 1.9 in/s and a 50 mph wind will apply vibration anywhere from 1.1 in/s up to 6.7 in/s. This is a significantly higher force than that of a blast from a quarry or blasting contractor.