Permeability of fault zones and how it changes over time

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• Professor Emily E. Brodsky, University of California, Santa Cruz
• Thursday 21 May 2015, 12:00-13:00
• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ.

If you have a question about this talk, please contact Catherine Pearson.

Permeability is commonly assumed to be a geometrically controlled constant that is fixed over human timescales. However, continuous measurements of permeability from tidal responses reveal that the apparent permeability can change significantly over time. Seismic waves from regional earthquakes can increase the permeability by factors of up to 3-4 and the permeability can recover slowly over a period of years. Permeability change is correlated to peak ground motion and we can recreate this fundamental observation with laboratory experiments. We have demonstrated through image analysis and variations in adhesive behavior with the ionic strength of the fluid that the mechanism of these experimental permeability enhancements is the clearing of clogged fractures. The fluid velocity during the oscillations is the best predictor of the resultant permeability enhancement. Transient permeability effects are particularly important in fault zones where the hydrogeology is coupled to the strength of the fault. For instance, we have directly measured the permeability recovery within a major fault following the 2008 M7.9 Wenchuan earthquake and showed that the evolution of the system continues for years after the mainshock.

This talk is part of the Institute for Energy and Environmental Flows (IEEF) series.

This talk is included in these lists:

• All Talks (aka the CURE list)
• Cambridge Energy Seminars
• Department of Earth Sciences seminars
• Institute for Energy and Environmental Flows (IEEF)
• NanoDTC Energy Materials Talks
• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ
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