I'm impressed that your buses are quiet. In SF, the city buses rattle my entire house when they pass by a half-block away. It's more "vibration" than "noise", but the whole house shakes and I hear clattering of little unbalanced objects in the cabinets and so on. In the last 5 years I've never experienced an earthquake that shook my house any more than the buses that pass by every 10 minutes.