StressRatio: Principal stress ratio

In abarbour/sibson: Calculate stability criterion for faults with friction

Description

Calculate the ratio of principal effective stresses

Usage

StressRatio(mu, theta, thresh = NULL, in.deg = TRUE)

Arguments

mu	numeric; the static coefficient(s) of friction
theta	numeric; optional; the orientation(s) of the fault with respect to the principal compressive stress
thresh	numeric; an arbitrary clipping level for the stress ratio
in.deg	logical; is theta given in degrees?

Details

The ratio of principal effective stresses, R, is given by

R=\frac{σ_1 - P}{σ_3 - P}=\frac{σ_1'}{σ_3'}=\frac{1 + μ/\tan{θ}}{1 - μ \tan{θ}}

where P is the pore fluid pressure. This function calculates R as given above and in Equation 4 from Sibson (1985).

References

Sibson (1995; Equation 4)

See Also

Sibson.fric, and Stability, which calculates the minimum R for reactivation.

abarbour/sibson documentation built on May 10, 2019, 4:08 a.m.