Dogs (especially large ones) jumping on trampolines can cause seismic tremors and possibly even a small earthquake if allowed to go on for over 15 minutes.

The danger comes from what is called “resonance frequency” which in lay terms is simply when you put energy into a substance or object at its resonance frequency, you force it to vibrate or resonate (forced vibration). It’s the same force at work as when marching soldiers break their cadence when crossing a suspension bridge. Source:  Fool Moon