How to isolate turntable from footstep shake or vibration

I don’t use powerful subwoofers. I use a full-range speaker system that is essentially flat in-room to below 20 hZ.

No sub here too, don’t know why people use sub at home for vinyl listening, and what is the speakers if they can’t reproduce bass? Sub is for cinema (digital) or as a competition for small bookshelf speakers that can’t reproduce bass at all. 

I’m with Tannoy System 15 mkII , don’t need any sub and life is good.

@cleeds, certainly an old Sota is not going to be the quietest turntable around but a record is at least one order of magnitude noisier than that old Sota. My new one, which will hopefully show up next month is as quiet as it gets. 
I use a calibrated mic to "listen" to my system all the time. It's program has an oscilloscope function and I can plot a frequency response curve which for this purpose needs to be near field. Rumble is a constant. Record noise is not. It is also much louder than rumble. But, you do not even have to measure it. You can see it in the subwoofers excursions. 
To be short, there is plenty of noise between 3 and 12 Hz. With a flat record it is true that between 0 and 12 Hz is relatively quiet. Relatively. 
It is also true that a sub sonic filter will be useful particularly for the idler wheel drive people. For people like me who use subwoofers boosted to realistic levels subsonic filters are essential for vinyl users unless you never listen over 75 dB.  Also if you do not want to rocket your subwoofer drivers into the next county a mute switch is a nice addition. 

Esputnix, that is wonderful. I could not believe Oracle would make such a design error. It is nice not to have to tip toe around;-)

Haha on me. Thank you, thecarpathian, for correcting me. I was indeed thinking of the Tacoma bridge, not the Verrazano. Only today did I see my error. Anyway, the point of my analogy still stands, or falls.

If the Verrazano were to shake itself to death, THAT would be spectacular.

Great bargain in Audio-Silent Running Audio (SRA) VR platform.
Think they are new $1500 built for your TT.
When I installed mine, all of a sudden, my Garrard 301 was able to preform as designed. A $10K TT turned into a $20K+ TT.
No exaggeration. I was floored and bought another for my preamp.