I've only ever experienced a big earthquake once, which was in Bangkok a couple of months ago. And if I had known it was an earthquake, I probably would've reacted differently. Not knowing what was happening, and genuinely thinking my building was about to collapse on top of me was one of the scariest feelings in my life.
It would, because then at least you know it's an earthquake, and you kind of know what to expect. Not know it was an earthquake, and wondering why your building is shaking and making so much noise, thinking you're about to die in some freak building collapse is pretty terrifying.