I was watching this video of an erupting volcano. Some Guys in the comments tried to estimate how far away the volcano is by using the delay until the "shock-wave" hits the camera and the speed of sound in air. However, shock-waves can travel much faster than the speed of sound.
Is there a way to tell (or estimate) if what we are hearing is actually (still) a shock-wave? From this paper on hand clapping and shock-waves I conclude, that not all "bangs" need to be caused by shock-waves. And shock-waves can be only very shortly lasting, especially if there is not much energy involved.
And is the result viable when we calculate the distance in the way described above?