Perfettini, H. and Avouac, J.-P. (2004) Stress transfer and strain rate variations during the seismic cycle. Journal of Geophysical Research B, 109 (B6). Art. No. B06402. ISSN 0148-0227. http://resolver.caltech.edu/CaltechAUTHORS:20110110-161256950
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The balance of forces implies stress transfers during the seismic cycle between the elastobrittle upper crust and the viscoelastic lower crust. This could induce observable time variations of crustal straining in the interseismic period. We simulate these variations using a one-dimensional system of springs, sliders, and dashpot loaded by a constant force. The seismogenic zone and the zone of afterslip below are modeled from rate-and-state friction. The ductile deeper fault zone is modeled from a viscous slider with Newtonian viscosity ν. The force per unit length, F, must exceed a critical value F_c to overcome friction resistance of the fault system. This simple system produces periodic earthquakes. The recurrence period, T_(cycle), and the duration of the postseismic relaxation phase, which is driven dominantly by afterslip, then both scale linearly with ν. Between two earthquakes, interseismic strain buildup across the whole system is nonstationary with the convergence rates V_i, just after each earthquake, being systematically higher than the value V_f at the end of the interseismic period. We show that V_i/V_f is an exponential function of α = T_(cycle)/T_M ∝ Δτ/(F – F_c ) ∝ Δτ/(νV_ 0), where Δτ is the coseismic stress drop and V_0 is the long-term fault slip rate. It follows that departure from stationary strain buildup is higher if the contribution of viscous forces to the force balance is small compared to the coseismic stress drop (due to a low viscosity or low convergence rate, for example). This simple model is meant to show that the far-field deformation rate in the interseismic period, which can be determined from geodetic measurements, might not necessarily be uniform and equal to the long-term geologic rate.
|Additional Information:||© 2004 American Geophysical Union. Received 28 November 2003; revised 15 March 2004; accepted 10 May 2004; published 22 June 2004. We are grateful to Massimo Cocco, Teruo Yamashita, and Sandra Stancey for their comments which have been most helpful to improve the manuscript. This is Caltech contribution 9001.|
|Group:||Caltech Tectonics Observatory, Caltech Tectonics Observatory. Indo-Asian Collision Zone|
|Subject Keywords:||earthquake cycle; postseismic relaxation; GPS; Geodesy and Gravity: Seismic deformations; Geodesy and Gravity: Rheology of the lithosphere and mantle; Seismology: Seismicity and seismotectonics; Seismology: Earthquake parameters; Seismology: Earthquake dynamics and mechanics|
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|Official Citation:||Perfettini, H., and J.-P. Avouac (2004), Stress transfer and strain rate variations during the seismic cycle, J. Geophys. Res., 109, B06402, doi:10.1029/2003JB002917|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||26 Jan 2011 19:23|
|Last Modified:||26 Dec 2012 12:50|
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