Rainwater may play an important role in the process that triggers earthquakes, according to new research.
Researchers from the University of Southampton, GNS Science (New Zealand), the University of Otago, and GFZ Potsdam (Germany), identified the sources and fluxes of the geothermal fluids and mineral veins from the Southern Alps of New Zealand where the Pacific and Australian Plates collide along the Alpine Fault.
From careful chemical analyses, they discovered that fluids originating from the mantle, the layer below the Earth’s crust, and fluids derived from rainwater, are channelled up the Alpine Fault.
By calculating how much fluid is flowing through the fault zone at depth, the researchers showed for the first time that enough rainwater is present to promote earthquake rupture on this major plate boundary fault.
Lead researcher Dr Catriona Menzies, from Ocean and Earth Science at the University of Southampton, said:
“Large, continental-scale faults can cause catastrophic earthquakes, but the trigger mechanisms for major seismic events are not well known. Geologists have long suspected that deep groundwaters may be important for the initiation of earthquakes as these fluids can weaken the fault zones by increasing pressures or through chemical reactions.
“Fluids are important in controlling the evolution of faults between earthquake ruptures. Chemical reactions may alter the strength and permeability of rocks, and if enough fluid is present at sufficiently high pressures they may aid earthquake rupture by ‘pumping up’ the fault zone.”
Read the full press release on the University website.