How effective was the US attack on Iran’s nuclear sites? A visual guide
Long regarded as the most difficult military target among Iran’s nuclear sites, the uranium enrichment facilities at Fordow – the primary target of the operation – are buried beneath the Zagros mountains. Reports have suggested that the site was constructed beneath 45-90 metres of bedrock, largely limestone and dolomite.
Some experts have suggested the layering of the sedimentary rocks, including faults, would also make it more difficult to strike the centrifuge array, providing a kind of geological cushioning against a blast wave.
Magmatic rock would be harder to penetrate - or tunnel.
Most likely the strata would be angled which could deflect the penetration.
Israeli intelligence is very good - good enough to have access to test bore results (if any) we don't know.
Maximum damage would be detonation inside or collapse into the facility. A close second would be structural compromise of the rock above with the resultant instability rendering the facility unusable. Whether the Iranians would publish photos of an undamaged facility is questionable as they may prefer to pretend it was destroyed and continue to use it without concern that Trump will give it another try.