I agree the SRB was the start of the huge explosion that somehow involved liquid hydrogen. I was posting that example because I was replying to an example where it was gaseous hydrogen combustion and because for the plane in the post it is liquid hydrogen which is used.
I don’t mind talking to non-expert as long as they don’t believe they know what they don’t know and do not insist they know better when they don’t.
From your comment I don’t know what “ET” means but I suppose “SRB” is something like side booster rocket solid rocket booster (?) I am not an expert of the space shuttle so please tell me if it pleases you to do so.