No... The loud sound wasn't caused by the GS's explosion. It was caused by the black figure suddenly sprinting forward at speeds way beyond the sound barrier.
It was so quick that it broke through the sound barrier with the first step.
A large shockwave rose from the movement and ruined the already ruined surroundings even more.
The few remaining trees which were too close to the exchange were all uprooted and thrown into the distance.
The girls were caught by surprise as they didn't expect something like that to happen. The wave reached them before they could properly put up their defence.
They were afraid that they might die from the shockwave after surviving everything else. And that would be a funny and stupid death since they had more than enough time to get away but they couldn't control their curiosity...
