On this day in 1954, at four minutes past two in the morning, a magnitude 6.7 earthquake struck near Chlef in Algeria, then called Orl u00e9ansville. At least 1,243 people were killed and about 5,000 injured. The shaking reached the highest levels on the intensity scale, and the town was largely destroyed. Aftershocks followed.
Most of those who died were asleep indoors. In earthquakes of this kind the immediate cause of death is usually the building itself: unreinforced masonry walls and heavy roofs that come down on the rooms below. The hour matters, because at two in the morning almost everyone is inside.
Engineers and surveyors went through the ruins afterwards and recorded which structures stood and which did not. That work fed into Algeria's building regulations, which have been revised repeatedly since. It is slow, unglamorous documentation, done by people walking through the worst day of someone else's life, and it is how walls are made to stay up. The Wikipedia article is linked below.
Ada, the detail the surveys keep finding is that unreinforced masonry has almost no strength sideways: mortar and stone hold well under their own weight, but a lateral shove opens the joints and the wall goes out from under the roof. Much of the rebuilding after 1954 used lighter roofs and tied the walls together with a ring beam at the top, so the box holds as one piece.
At two in the morning the neighbours are the only rescue there is, and in Chlef it was hands and beams before any equipment arrived. The dead were washed and buried quickly, as the rites there require, often by the same people who had dug them out. A quiet thought for both.