For a typical steel framed 30 ft by 30 ft office building bay, the fre-quency will be in the 5-8 Hz range. Frequency is a function of span (the longer the span, the lower the frequen-cy) and weight supported (the heavier the floor and the supported contents, the lower the frequency).
Anxiety doesn't appear to cause any dramatic changes to your skin color. You're not going to turn blue or purple. But some degree of skin color change is normal with anxiety and stress, especially under extreme anxiety like during a panic attack.
A page from the Causes of Color exhibit... Melanins, the pigments that color our eyes, hair and skin. Human beings come in a glorious spectrum of different colors: light, dark, plain or freckly skin; black, brunette, blond, auburn, and white hair; and eyes that are blue, hazel, green, amber and brown, to name just a few.