Why does the mother of bombs explode in the air instead of underground?

Aerial detonation helps "Mother of the bombs" GBU-43 achieves maximum damage, compared to detonation when touching ground.

GBU-43 Massive Ordnance Air Blast (MOAB) , nicknamed "Mother of All Bombs" , is a large conventional bomb developed by the United States. At the time of its launch, it was considered the most powerful non-nuclear weapon in the world.

When it began to fall freely, MOAB quickly separated from the racks and opened the navigation net. Thanks to the global positioning system (GPS) and computer control, these nets help navigate MOAB to the goal.

A MOAB result with grid control wing system.(Photo: Wikipedia).

MOAB fruit does not reach the ground of the underground system. Like most large weapons, including nuclear bombs, it exploded in the air. MOAB trigger detonator is 2m above the ground with the equivalent power of 11 tons of TNT.

The reason it exploded in the air, instead of exploding when touching the ground, was to cause overpressure . It is a sudden increase in air pressure caused by a bomb. This pressure change spreads into shock waves in all directions. Any weapon, tunnel or creature within the bomb's damage range is completely destroyed.

If MOAB explodes when it hits the ground, a lot of pressure waves will hit the ground, creating bomb craters. The ground is hard and thicker than air many times, causing shock waves to be annihilated very quickly. MOAB exploded on the ground still causing a lot of damage within a certain range, but detonating at a height of 2 meters will widen the scope of damage many times.

Besides, when the bomb explodes in the air, the overvoltage wave will spread in all directions, including downward. The downward wave will bounce, passing through the hot and thin air created by the explosion just before.

Combined shockwave process of MOAB.(Photo: Business Insider).

In this environment, pressure waves move faster. Feedback waves can catch up with the initial shock waves. They combine, creating a "combined shock wave" , capable of doubling the bomb's destructive power.

The shockwave combined creates a great pressure on the ground, which can collapse the tunnel and detonate underground mines without wasting energy. If MOAB explodes in a flat terrain, other than the mountainous terrain of Nangarhar province, it will create an explosion with a radius of 1.6 km.