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Elastohydrodynamic lubrication of faults

Brodsky, Emily E. and Kanamori, Hiroo (2001) Elastohydrodynamic lubrication of faults. Journal of Geophysical Research B, 106 (B8). pp. 16357-16374. ISSN 0148-0227. doi:10.1029/2001JB000430.

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The heat flow paradox provides evidence that a dynamic weakening mechanism may be important in understanding fault friction and rupture. We present here a specific model for dynamic velocity weakening that uses the mechanics of well-studied industrial bearings to explain fault zone processes. An elevated fluid pressure is generated in a thin film of viscous fluid that is sheared between nearly parallel surface. This lubrication pressure supports part of the load, therefore reducing the normal stress and associated friction across the gap. The pressure also elastically deforms the wall rock. The model is parameterized using the Sommerfeld number, which is a measure of the lubrication pressure normalized by the lithostatic load. For typical values of the material properties, slip distance and velocity, the Sommerfeld number suggests that lubrication is an important process. If the lubrication length scales as the slip distance in an earthquake, the frictional stress during dynamically lubricated large earthquakes is 30% less than the friction with only hydrostatic pore pressure. Elastohydrodynamic lubrication also predicts a decrease in high-frequency (>1 Hz) radiation above a critical slip distance of a few meters. This prediction is well matched by the strong motion data from the 1999 Taiwan earthquake. The observed 2 orders of magnitude variation in scaled radiated energy between small (M_w < 4) and large earthquakes (M_w > 6) is also predicted by the lubrication model.

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URLURL TypeDescription DOIArticle
Brodsky, Emily E.0000-0002-6855-6860
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 2001 by the American Geophysical Union. Paper number 2001JB000430. Received May 12, 2000; revised December 1, 2000; accepted March 26, 2001. We are indebted to Brad Sturtevant for numerous stimulating conversations and insightful comments that provided the foundation for this work. We dedicate this paper to his memory. Y. Ben-Zion, J. Brune, N. Sleep, and V. Lyakhovsky provided constructive reviews. This work was supported in part by the National Science Foundation grant NSF EAR-9909371 and the US Geological Survey grant USGS HQGR0035. The Taiwan data are taken from W.H.K Lee, T.C. Shin, K.W. Kuo, and K.C. Chen, CWB Free-Field Strong-Motion Data from 921 Chi-Chi Earthquake: Volume 1, Digital Acceleration Files on CD-ROM. This is contribution 8700 of the Caltech Division of Geological and Planetary Sciences.
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Caltech Division of Geological and Planetary Sciences8700
Issue or Number:B8
Record Number:CaltechAUTHORS:20141110-152615085
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Official Citation:Brodsky, E. E., and H. Kanamori (2001), Elastohydrodynamic lubrication of faults, J. Geophys. Res., 106(B8), 16357–16374, doi:10.1029/2001JB000430
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51533
Deposited By: Tony Diaz
Deposited On:11 Nov 2014 00:20
Last Modified:10 Nov 2021 19:12

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