The inner ear has miraculous functions. One is the levitating function. This is part of what cues your body to feel weightless when you free fall, that you should push harder with your legs on an incline, that tells you you're more secure when sitting. It is instrumental in the music your body makes called movement. In my orchestra, it was a violin out of tune and on a different sheet of music: screeching, out of sink, and wildly erratic.
While I was sitting, I would suddenly feel like a phantom was pushing my body back. When I was walking on level ground, it would feel like the ground was suddenly falling, ...or rising quickly and unpredictably. My body would react "as if" and with in milliseconds of my sympathetic nervous system going into hyperdrive, reason would catch me and I would realize we actually hadn't entered into an Escher drawing or the movie "Inception." ("Lizzy, you aren't really feeling like your falling because in a higher state of consciousness you are careening down an elevator shaft." Although I did not say this to myself at the time because the movie did not come out until just last year, right?) I would ground myself against a wall, in a chair, or keep moving in a deliberate walk to scream reality at my body that was totally out of sync. And then I would break out in a sweat. (That is a lot of work "behind the scenes," eh?).
Puerto Escondido had an earthquake the first night we were there. I was on my hands and knees pushing my suitcase under my bed. It felt like the ground was rising. When reason caught me, I fell to my knees and felt around at the ground to remind me it was still; it wasn't. I panicked. "HOLY CRAP! Save me!"
I looked at my parents. And caught their eyes. They were panicked too. They were panicked too!
"I think that was an earthquake!" said my dad, just a couple seconds later.
"Phew. Really? For real? ..., ... Alleluia! It was just an earthquake." The locals talked about it for days.