The first explosion (jet fuel) leaves fumes and the second (diesel) magnifies the blast.
What happened at the WTC was really a 0.5 ton mini nuke in NYC because of the structural damage to the buildings around there. The jet fuel still in the air maginifed the blast to the surrounding buildings
The buildings survived the impact. It was the fire that took them down.
Are you sure you don't mean .5 KILOtons?