While everyone's having a rocking good bad time up top, big things are happening deep underground as an earthquake strikes. Of course, minerals from the Earth's core are known to seep out, but now scientists have discovered that gold veins are actually formed instantaneously due to a massive drop in pressure as an earthquake rumbles on.
Essentially what happens, according to a new paper in Nature Geoscience, is that as the plates slip long the fault line, the 'fault jogs' -- sideways zigzag cracks connecting the main fault plains -- open up. That instantly reduces the pressure inside them, from somewhere in the region of 290MPa down to just double our air pressure at sea level (around 0.2MPa). The rapid depressurisation instantly vaporises any liquid trapped between the pieces of rock, depositing any gold they contain on the rock.
Apparently even the smallest earthquakes, which barely register for the humans living above, deposit gold and other minerals on the rock, which is one reason why gold ore looks so marbled with gold veins. The researchers reckon that they might be able to use seismic information to be able to track likely spots where lots of gold has formed, which is certainly good news for prospectors of the lustrous metal. They still exist, right? [Nature]
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