Sound moves 4-times faster in water than in air, I assume even faster in ground surface, so let’s just assume it arrives instantly via ground. This would mean a

Sound moves 4-times faster in water than in air, I assume even faster in ground surface, so let’s just assume it arrives instantly via ground. This would mean a delay like in lightning/thunder, which is what one can see in the video (2–3 seconds ~ 0.5–1 km). (This is the restaurant https://goo.gl/maps/td5K1vxUDBN4i1CA8 https://goo.gl/maps/td5K1vxUDBN4i1CA8) But I could equally imagine it’s some lesser explosion before the main blast.