Iran has been rocked by two earthquakes after Israeli air strikes hit key nuclear sites as the conflict between the two countries entered a fourth day. A 2.5 magnitude tremor struck near Iran's Fordow nuclear centre shortly after a missile strike targetted the site amid escalating military tensions between the two nations.

Uranium ore that miners dig up is relatively harmless. But it contains tiny amounts of a rare radioactive isotope, Uranium 235, that can be used to power nuclear reactors at low levels of enrichment, and to fuel atom bombs at higher levels. The percentage of U-235 in mined uranium is less than 1 percent.