My house was destroyed in the Loma Prieta earthquake of 1989. By destroyed I mean that it fell off it's foundations (and got super wonky), had windows pop out, shatter, etc. I don't mean it collapsed entirely. But, everything not bolted down did end up as a giant pile in the center of the room. Every canned good, plated, spice jar, etc. was piled on the kitchen floor. Every book shelf (and book) ended up in the middle of the room. An aquarium flew off a dresser and shattered, propelling glass (and fish) everywhere. Had I not run to a door, I think my chanced of injury would have been much greater. Part of this isn't necessarily about the structure of a door frame, but because, as a passageway, there weren't really any objects to fall on me. Slamming doors are a concern though.