It occurs to me that the amount of explosive was quite small and that they were a safe distance away from it. Someone has suggested that they were clearing a side branch. But what if it is an expedient way of dissipating low levels of methane? My guess is that kind of stuff could build up slowly to a level that it becomes dangerous if it were to explode - so they nail it before it becomes an issue. It really wouldn’t take much explosive material to demonstrate that effect.
