most of the failures seen aren't straight breaks, but happen over a period of time after a lot of fatigue and stress.

an initial impact/crack probably produced a stress raiser , and the cyclical stresses made the crack grow until there wasn't enough material to carry the stresses, and then the crank failed catastrophically.

corrosion from salt and other shi+e on the roads probably also has a part to play in this.

this is probably the time to advise everyoneto start a regular regime of polishing and checking for any cracks/deformation on load-bearing parts like cranks and stems.

fsnl
sparky