Lyell Collection
Geological Society, London, Special Publications
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Imber, J.
Right arrow Articles by Collettini, C.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 2008; v. 299; p. 151-173;
DOI: 10.1144/SP299.10
© 2008 Geological Society of London

Mechanical consequences

Frictional-viscous flow, seismicity and the geology of weak faults: a review and future directions

J. Imber1, R. E. Holdsworth1, S. A. F. Smith1, S. P. Jefferies1 & C. Collettini2

1 Reactivation Research Group, Department of Earth Sciences, University of Durham, South Road, Durham, DH1 3LE, UK (e-mail: jonathan.imber{at}durham.ac.uk)
2 Geologia Strutturale e Geofisica, Dipartimento di Scienze della Terra, Università degli Studi di Perugia, Piazza dell'Università 1, 06100, Perugia, Italy

Previously hypothesized fault weakening mechanisms include faults lined by low-friction clay gouges, elevated pore pressures within fault cores and/or the operation of dynamic weakening during seismic slip. Geological studies to support dynamic weakening are still in their infancy and there is little geological evidence for the widespread occurrence of low-friction gouges. The cores of some ancient faults exhumed from <5 km depth contain sheared syntectonic mineral veins. This observation is consistent with elevated pore pressures, but the implications for long-term fault weakening are unclear. Experimental data and microphysical modelling suggest that frictional–viscous flow within phyllosilicate-rich fault rocks (phyllonites, some foliated cataclasites) can cause sufficient weakening of crustal faults to satisfy published heat flow constraints. These predictions are consistent with the common occurrence of phyllonite in the cores of large-displacement faults exhumed from >5 km depth. Comparison with seismological data suggests that some faults with phyllonitic cores are likely to generate large earthquakes. Future studies should establish the geological evidence for seismic slip within phyllonitic fault cores and quantify the partitioning between seismic slip and frictional–viscous flow. Further geological observations are also required to test the hypothesized mechanisms by which earthquakes can nucleate and propagate along phyllosilicate-rich faults.





This article has been cited by other articles:


Home page
 Geological Society, London, Special PublicationsHome page
C. A. J. Wibberley, G. Yielding, and G. Di Toro
Recent advances in the understanding of fault zone internal structure: a review
Geological Society, London, Special Publications, 2008; 299: 5 - 33.
[Abstract] [Full Text] [PDF]