I grew up in California, lived there for most of my life, and been through MANY earthquakes. I do not recall any booming sounds through any of them. Granted, I know that all earthquakes have different characteristics. Again, been through different types. The rolling action. The jolting, jarring action of some of them. Never any booming involved.
Lived between San Jose and San Fran for about 4 years and felt enough earthquakes for my lifetime. I'm a midwesterner by birth. In the biggest I felt (5.0) I was on the 5th floor of a building. There was a large bang, but several folks explained that was just the building moving....nothing to worry about.
Nothing to worry about? Sheesh!