This was a small addition (more like an extension) to the rear of a kitchen. A footing and slab was poured and 2 courses of block support the 4 foot “addition”. The corner blocks have kicked out at one corner. There does not appear to be any settling or currently any movement of the structure above it.
It appears that they were kicked out well before winter. Though it is hard to see from the inside, it is possible that there is a crack in the footing a few inches to the left of the shifted blocks.
That would have been my question as Michael just mentioned.
Is this foundation below the frost line?
It appears as the frost action has laterally applied the forces to the block wall and if not anchored properly to the sill of the house, would explain why you did not notice any movement within the dwelling.
JMO
Trying to help you here based on a little picture that tells us nothing but speculation and opinions based on what could or might have happened, because we do not see the whole picture as you obviously did.
If you did not hear what you wanted to hear, I guess we opologize for that and wish you luck in figureing it out on your own.
Then write it up as foundation displacement - monitor for changes, verify permits for addition and consider consulting a structural engineer for a definitive opinion. Now get get snippy with me young man!
The question about how deep the footing goes is nice to speculate about but with the lack of construction information and being the dead of winter, it’s not a question anyone can readily answer.
It is pretty much all speculation without an expert evaluation, just though some people would have something useful to add. A group of local inspectors had plenty to say and suggest.
I had no expectations of hearing one thing or another.