The house is on cement slab, about ten years old.

How long have the cracks been there? Come all at once or one here and one there over years? What town do you live in? I have tons more questions to help pin this down but we must start slow to help guide me in the right direction.

It is a rental, don't see it day to day. The renter mentioned it two years ago, got worst in the past year. In Northern CA. The house is two story. Had a General contractor look at it. He asked for a structural engineer to look at it.

Could be quake damage but your foundation must be moving for this many cracks.

I am in N. CA, which quake zone, but nothing apparent. Is there something like a thermal imaging device to see cracks in the foundations or pockets in the slab?