>You can quite clearly see the crater extends downwards below the pipe. In a similar and proportional way, a larger pipeline explosion would have a larger crater.
Yeah, if the NS pipe was buried.. was it? Oh, no, it wasn't.
> I think it was quite clearly an internal pressure build up, analogous to an internal pipe explosion.
If you think that is clear you need to review your knowledge of basic physics.
When a pipe ruptures due to internal pressure build up, it looks like this :
Theres a section of pipe missing, torn at the welds, and a crater.
Sure, there may not have been a "fireball explosion", but nonetheless, an explosive force, ie, the buildup of gas under the earth and under the pipe provided an explosive force external to the pipe.
Explain to me how pressure built inside the pipe at just that section inbetween the torn welds? If the pressure inside the pipe was enough to make the entire vessel rupture, it would have destroyed the entire pipe... not just one section...
