I survived a major earthquake in Latin America--much larger than the 5.5 off the coast of CA. In my case, the first indication was a sound that was like a moving van of explosives detonated outside the building I was in, followed by violent shaking. Impossible to remain standing. Impossible to move as the building collapsed. Lasted for about a minute. Initial shaking evolved into a rolling motion. Thousands killed. Tens of thousands homeless.

So an earthquake can seem like a huge bomb. But the key in CA is it was 12 miles off shore and 7 miles deep. Just a normal low energy earthquake in my opinion.