Stand in a doorway during an earthquake

What actually happened

The advice came from a real photograph: an unreinforced adobe house in California, collapsed, with the doorframe standing. In that specific construction it was true. In a wood-frame or steel-frame or reinforced-concrete building, the doorway is not a special structural element, and there is nothing to hold up.

The threat model was also wrong. In countries with modern building codes, buildings mostly do not pancake, and the overwhelming majority of earthquake injuries come from being hit by falling and flying objects, or from moving around during shaking. A doorway offers no overhead protection at all, while a table does exactly that. You are also very likely to be thrown off your feet, which is why the instruction is to drop before the earthquake drops you.

The USGS, the Red Cross, and FEMA all teach drop, cover, hold on, and the Great ShakeOut drills tens of millions of people in it annually. The advice differs in regions with a high risk of total collapse, where getting outside quickly may be better, so this is genuinely context-dependent. But the doorway line, which is still the first thing many adults say, has been withdrawn by the agencies that used to give it.