Tectonic Fragdrill

The only logical way that this thing can cause earthquakes is to imagine it as a miniature cyclonic torpedo.

Less of a vehicle and more of a earthquake making machine. Tectonic Fragdrills can make a pinpoint assault on the most volatile parts of the planet’s crust, resulting in a localized earthquake. How something that small of a machine can generate an earthquake, (even a small one) is up in the air, answer may most likely be maybe mundane, maybe space magic, maybe bullshit.

Hell, even as a industrial mining machine, the design makes no sense. Like, why the hell is there three drills? Not only that, but why the hell does one of them look like a screwdriver mounted on a flimsy arm-piece? It does not strike us as a versatile and durable machine. I highly doubt something like that could even drill past granite, let alone a planet's crust. It is what you call as being over designed, in which you have all these unnecessary clutter that ends up ruining the design aesthetics rather than improving upon it or making it more 'detailed'. Sometimes, being simple is the best and it shows.

And no, before you give GW the excuse that they are a modelling company and not an engineering company, the recent Termite and Hades Breaching Drill models are well-designed and competent tunnel-boring machines, so it is weird on just why they decided that this design was even remotely appropriate. A possible explanation is that Forge World has a far better design team than standard Games Workshop.

Overview

Nevertheless, the Tectonic Fragdrills are often mounted on a specially designed base that helps positions the machine before punching through the ground via a rail harness. You can think of it as an elevator of doom. Its unknown how the Imperium could get these machines back to the surface, although the most likely answer is that they are meant to be disposable; acting like a giant underground missile per se. Modern artificial seismicity is often caused by dumping a very large body of water (Like a dam), induce artificial sinkholes through sufficient underground mining and coring and most infamously, caused by an underground nuclear blast. So the Tectonic Fragdrill being an underground nuclear ICBM could be the most reasonable answer of it being able to create an earthquake. Still does not excuse it for its questionable design however.

Because of how much Genestealer Cults love to work at mining and industrial jobs (FOR. OBVIOUS. REASONS.), they have learned to harness these machines to cause maximum disruption to their foes on the battlefield, causing entire building foundations to collapse or creating a large sinkhole.