Projects per year
Abstract
Earthquakes cause rock fracturing, opening new flow pathways which can result in the mixing of previously isolated geofluids with differing geochemistries. Here we present the first evidence that seismic events can significantly reduce groundwater pH without the requirement for fluid mixing, solely through the process of dynamic rock fracturing. At the Grimsel Test Site, Switzerland, we observe repeated, short-lived groundwater pH drops of 1-3.5 units, while major and minor ion groundwater concentrations remain constant. Acidification coincides with reservoir drainage and induced microseismic events. In laboratory experiments, we demonstrate that fresh rock surfaces made by particle cracking interact with the in situ water molecules, likely through creation of surface silanols and silica radicals, increasing the H+ concentration and significantly lowering groundwater pH. Our findings are significant; pH exerts a fundamental control on the rate and outcome of most aqueous geochemical reactions and microseismic events are commonplace, even in seismically inactive regions.
Original language | English |
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Journal | Geophysical Research Letters |
Early online date | 17 Dec 2020 |
DOIs | |
Publication status | E-pub ahead of print - 17 Dec 2020 |
Keywords
- pH
- groundwater
- microseismic events
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Projects
- 1 Finished
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Doctoral Training Partnership (DTA - University of Strathclyde)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/14 → 30/09/18
Project: Research - Studentship