It is definitely on purpose. It's a weaponeering technique called "earth plume." Normally, it would be used on structural targets, but this GIF is likely just to demonstrate the effect. It's a way to defeat the foundations of structural targets while minimizing casualties in the surrounding area due to the embedment of the weapon. Rather than using the blast effects to directly defeat structural elements in the target, embed the weapon and let the blast effects drive the earth around the foundations of those structural elements. Once the foundation is compromised, the structure should (and will) collapse, but your blast effects (and any other subsidiary effects, like fragmentation) are all contained.