Experimental postseismic recovery of fractured rocks assisted by calcite sealing

Postseismic recovery within fault damage zones involves slow healing of coseismic fractures leading to permeability reduction and strength increase with time. To better understand this process, experiments were performed by long‐term fluid percolation with calcite precipitation through predamaged qu...

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Bibliographic Details
Published in:Geophysical research letters 2017-07, Vol.44 (14), p.7228-7238
Main Authors: Aben, F. M., Doan, M.‐L., Gratier, J.‐P., Renard, F.
Format: Article
Language:English
Subjects:
Asperity
Calcite
calcite sealing
Conduits
coseismic damage
Dissolution
Dissolving
Duration
Earthquake damage
Earthquakes
Elastic waves
Evolution
Flow channels
Fractures
Healing
microtomography
Percolation
Permeability
postseismic recovery
Precipitates
Precipitation
Quartz
Recovery
Sealing
Seismic activity
Seismic velocities
Seismic wave velocities
Strength
Temperature effects
Velocity
Wave velocity
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Summary:Postseismic recovery within fault damage zones involves slow healing of coseismic fractures leading to permeability reduction and strength increase with time. To better understand this process, experiments were performed by long‐term fluid percolation with calcite precipitation through predamaged quartz‐monzonite samples subjected to upper crustal conditions of stress and temperature. This resulted in a P wave velocity recovery of 50% of its initial drop after 64 days. In contrast, the permeability remained more or less constant for the duration of the experiment. Microstructures, fluid chemistry, and X‐ray microtomography demonstrate that incipient calcite sealing and asperity dissolution are responsible for the P wave velocity recovery. The permeability is unaffected because calcite precipitates outside of the main flow channels. The highly nonparallel evolution of strength recovery and permeability suggests that fluid conduits within fault damage zones can remain open fluid conduits after an earthquake for much longer durations than suggested by the seismic monitoring of fault healing. Key Points Calcite sealing assisted recovery experiments detail the evolution of seismic velocities and permeability with time The P wave velocity recovers but permeability remains more or less similar due to the location of calcite precipitation Results imply that fault zones remain fluid conduits for longer than seismic observations suggest
ISSN:0094-8276
1944-8007
DOI:10.1002/2017GL073965