Models of recurrent strike‐slip earthquake cycles and the state of crustal stress

Publisher: John Wiley & Sons Inc

E-ISSN: 2156-2202|96|B13|21623-21640

ISSN: 0148-0227

Source: Journal Of Geophysical Research, Vol.96, Iss.B13, 1991-12, pp. : 21623-21640

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Abstract

Numerical models of the strike‐slip earthquake cycle, assuming a viscoelastic asthenosphere coupling model, are examined. The time‐dependent simulations incorporate a stress‐driven fault, which leads to tectonic stress fields and earthquake recurrence histories that are mutually consistent. Single‐fault simulations with constant far‐field plate motion lead to a nearly periodic earthquake cycle and a distinctive spatial distribution of crustal shear stress. The predicted stress distribution includes a local minimum in stress at depths less than typical seismogenic depths. The width of this stress “trough” depends on the magnitude of crustal stress relative to asthenospheric drag stresses. The models further predict a local near‐fault stress maximum at greater depths, sustained by the cyclic transfer of strain from the elastic crust to the ductile asthenosphere. Models incorporating both low‐stress and high‐stress fault strength assumptions are examined, under Newtonian and non‐Newtonian rheology assumptions. Model results suggest a preference for low‐stress (a shear stress level of ∼;10 MPa) fault models, in agreement with previous estimates based on heat flow measurements and other stress indicators.