Probably better off asking in one of the materials or automotive forums... this forum is more for large-scale disasters, like a plane crashing or a power plant exploding.
Well without more information the only thing I can tell is that it looks like a very brittle fracture to me, there are no signs of mechanical distortion but again one only one view of half a failed component it’s very hard to tell.
“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein
What are the indications, a "catastrophic failure"
Would be interesting to see more details.
And - oops, didn't mean to do that, boss.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
Fracture like that - out of the skirt and well below the centerline of the crank - looks to me like the bare block was probably dropped on that corner (as others have said).
As far as fracture surfaces, the cast iron used for engine blocks is typically not very ductile. I'd expect a failure to look just like this. Nothing strange jumps out at me.
We once delivered a high-precision instrument to the customer, who promptly returned same, claiming that it was grossly misaligned and unusable. We queried whether it had been dropped, and they vehemently denied any such possibility.
When we got it back, the front corner of a 3" thick aluminum mounting flange was bent upward by a half inch; right, no one dropped it.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
I just picked up a replacement for my new 32" curved monitor... I damaged the first on by leaning it forward (onto my mouse)... I asked the manager if I could get the replacement at the sale price, and he said OK. It was my own carelessness; I did not try to use the 'already broken' line...
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?