Rainwater discovered deep inside the Earth

Friday, July 18, 2014, 3:44 PM - Researchers at the University of Southampton have found that rainwater can penetrate below the Earth's upper crust -- a discovery that could change our understanding of how earthquakes and mineral deposits form.

The study marks the first time that rainwater has been found penetrating the earth's ductile crust, an area were temperatures exceed 300 degrees Celsius. 

This could have important implications, given that fluids in the Earth's crust can weaken rocks which may cause earthquakes to develop along fault lines. These fluids can also contain high concentrations of valuable deposits, like gold.

Researchers now believe that rainwater may play a critical role in both these "important processes".

"When fluids flow through the crust they leave behind deposits of minerals that contain a small amount of water trapped within them," says Dr. Catriona Menzies, the study's lead author, in a statement.

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"We have analysed these waters and minerals to identify where the fluids deep in the crust came from. Fluids may come from a variety of sources in the crust. In the Southern Alps fluids may flow upwards from deep in the crust, where they are released from hot rocks by metamorphic reactions, or rainwater may flow down from the surface, forced by the high mountains above. We wanted to test the limits of where rainwater may flow in the crust. Although it has been suggested before, our data shows for the first time that rainwater does penetrate into rocks that are too deep and hot to fracture."

The team is now in the process of searching for a possible link between deep-Earth rainwater and natural earthquake cycles.

The complete paper can be found in Earth and Planetary Science Letters.