why are doorways the safest place to stand in an earthquake?

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why are doorways the safest place to stand in an earthquake?

In: Engineering

They’re not, there’s a notion that a door way would be reinforced in some way. That’s not typically the case though, the best practice is still to get under a sturdy table or desk or the like. Or you could try to get next to a large solid object and make a little safety triangle where of anything large falls the thing like a bed you’re next too could prevent if from falling directly on you.

That’s actually not true for modern buildings!

This myth started because the walls in buildings used to be just a wall material,, with nothing inside. This means the walls had no support and would collapse easily when an earthquake occurred. Doorframes were frames in the wall meant to support the weight above them, meaning they were strong supports to the wall. Often times, this meant, they were left standing after an earthquake occurred. Today, since the walls are all supported on the inside, often with wood squares/triangles (frames), doorways are no longer as strong.

The best thing to do during an earthquake would be to get under any desk, chair, upside down bin, etc. as quick as possible. You’ll have better chances there than running for the nearest doorway.

The most common danger in an earthquake is falling objects and other things like broken glass that can go flying, and a doorway doesn’t protect you from either of those necessarily. They’re definitely a little bit reinforced and they aren’t usually near objects on the ceiling that can fall, but overall you still want to find the heaviest and sturdiest piece of furniture that you can fit under and stick there to avoid being hit by other objects.

The doorway idea might come from pictures of serious earthquakes where a house has collapsed but the doorframe is still standing, but the doorframe being left standing is far from a guarantee and that’s something that would only be happening in the worst-case scenario anyways.

Both walls and ceilings can fall on you during an earthquake. (Your floor is somebody else’s ceiling.)

A wall normally falls either toward the inside of the building or toward the outside. A wall rarely falls straight down. Therefore, the safest place is in a doorway. If the doorway falls as well as the wall, the door frame will protect you from large pieces of wall or ceiling crushing you. (Small pieces mostly give you bruises.)

A ceiling, on the other hand, will usually fall straight down. The safest place to be during an earthquake is not under a ceiling. If you are in a building, this means you are in a doorway.

This is a recommendation for buildings with concrete carcass with masonry of any kind, not so applicable for light wooden frame buildings. In concrete carcass buildings with masonry, the walls might crack and collaps during an earthquake, but doors and windows have concrete headers, which are an additional piece of reinforcement we can count on during an earthquake, though a better solution is to stand under a beam, if one you can easily identify it.