Striking gold: Earthquakes deposit precious metal

PARIS (AFP) - Solid gold can be deposited in Earth's crust "almost instantaneously" during earthquakes, said a study published in the journal Nature Geoscience on Sunday.

The gold is formed when a tremor splits open a fluid-filled cavity in the Earth's crust, causing a sudden drop in pressure, according to a team of Australian researchers.

This, in turn, causes the fluid to expand rapidly and evaporate, and any gold particles that had been dissolved in it to "precipitate almost immediately", said a Nature press release.

"Repeated earthquakes could therefore lead to the build up of economic-grade gold deposits." The researchers said much of the world's known gold was derived from quarts veins that were formed during geological periods of mountain building as long as three billion years ago.