Shaking without sound?
I was in a crowded restaurant and my ears have been clogged for days, so I’m not sure that there wasn’t sound.
If other people heard aircraft sounds, that would explain why no one acted like they thought there was an earthquake.
But they also weren’t wondering why aircraft were flying low.
But I suppose at various points of time in years past when I saw or heard low-flying aircraft I either thought they were training flights or law enforcement searching for someone and didn’t spend much time wondering about it.