Details of Award
NERC Reference : NE/C001117/1
Fluid flow properties of the fracture damage zone surrounding large strike slip faults
Grant Award
- Principal Investigator:
- Professor DR Faulkner, University of Liverpool, Earth Surface Dynamics
- Grant held at:
- University of Liverpool, Earth Surface Dynamics
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Natural Resource Management
- Environmental Risks and Hazards
- Science Topics:
- Properties Of Earth Materials
- Tectonic Processes
- Hydrological Processes
- Geohazards
- Abstract:
- Characterizing how fluids move around the Earth's crust is critical in order to understand a wide range of geological phenomena. For example, the nucleation of earthquakes on faults is very poorly understood, illustrated by observations that the San Andreas fault in California is apparently much weaker than is predicted by laboratory friction experiments. Recent studies have suggested that pockets of high fluid pressure trapped at depth within the fault zones helps weaken faults, initiating earthquakes, and that post-failure, consequent movement of these fluids trigger aftershocks. Hence it is clear that the quantification of the fluid flow properties of fault zones is central to understanding earthquake processes. To this end, a $30M project has been initiated to drill through the San Andreas fault at 3.5 km depth at Parkfield, California, where a cluster of microseismicity in the source region of a repeating M6 earthquake is occurring. The San Andreas Fault Observatory at Depth (SAFOD) will monitor stress, fluid pressure, fluid chemistry and seismicity from within the fault zone. As part of this project, core recovered from the borehole will provide a one-dimensional view of the San Andreas fault, and allow laboratory measurements of a number of the physical properties of fault zone, including permeability. Faults consist of two parts; fine-grained fault gouge (rock 'flour') where slip occurs, and the surrounding damage zone, where initially intact rocks are pervasively fractured on a number of different scales. These act as fluid flow barriers and conduits respectively. Although some research has concentrated on the hydraulic properties of fault gouge, there are remarkably few studies relating to the structure and hydraulic flow properties of rocks within the damage zone. I plan to make permeability measurements of rock recovered from the damage zone of the San Andreas fault from the SAFOD borehole at different distances from the fault core. I propose to conduct high pressure laboratory deformation experiments in order to reproduce the small scale damage seen on natural faults. These experiments will be made on initially intact rocks, and the evolution of the fluid flow properties during progressive damage will be continuously monitored. Microstructural observations of the microfracture damage within these cores will be compared to the damage produced in experimentally deformed samples for which the entire stress-strain and porosity-permeability history is known. Finally, field studies of two large strike-slip fault zones will allow a two-dimensional view of damage surrounding faults to be established. Hence the comparison of all these data from active fault zones at depth, ancient fault zones exposed at the surface and simulated fault damage in the laboratory will provide a picture of how faults control fluid flow.
- NERC Reference:
- NE/C001117/1
- Grant Stage:
- Completed
- Scheme:
- Small Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Small Grants
This grant award has a total value of £31,064
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Other Costs | Total - Equipment |
|---|---|---|
| £8,429 | £16,854 | £5,781 |
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