Thank you for the information!

Sometimes it’s worth pausing a moment when seeing a “It’s well known that…” to check the timeline because the construction of Arecibo might well have taken place (or planned) before it was known (let alone well known).

Edit: a bit more searching suggests that this was studied in 1947 (Andrade’s Creep Law and the Flow of Zinc Crystals, by AH Cottrell)