Complex sentence: By penetrating the ground it directs all of its energy into it, this means that a relatively low yield may be able to produce seismic forces beyond those of an air burst or even groundburst of a weapon with twice its yield.
Split into simpler sentences: By penetrating the ground it directs all of its energy into it. A relatively low yield may be able to produce seismic forces beyond those of an air burst or even groundburst of a weapon with twice its yield.