okada85: Okada Fault Deformation Model

Description Usage Arguments Details Value Note Author(s) References See Also Examples

Description

Calculate the deformation due to a fault based on Okada 1985 code.

Usage

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okada85(e = 0, n = 0, depth = 0, strike = 20,
dip = 20, L = 5, W = 3, rake = 20, slip = 1, U3 = 1, nu = 0.25)

Arguments

e

vector or matrix, Easting Observation, km

n

vector or matrix, Northing Observation, km

depth

depth of fault

strike

degrees, strike of fault, measured from north

dip

degrees, strike of fault, measured from horizontal

L

Length, km

W

Width, km

rake

rake (degrees)

slip

slip

U3

dilitation (m)

nu

Poisson's ration, default=0.25

Details

Computes displacements, tilts and strains at the surface of an elastic half-space, due to a dislocation defined by RAKE, SLIP, and OPEN on a rectangular fault defined by orientation STRIKE and DIP, and size LENGTH and WIDTH. The fault centroid is located (0,0,-DEPTH).

R-Code is a translation of original Matlab code by Francois Beauducel. UNC student Lan Ngo worked on the first version and J. M. Lees tested, verified and finalized the package.

Value

list:

uE

East deformation

uN

North deformation

uZ

Vertical deformation

uZE

tilt vertical east

uZN

tilt vertical north

uNN

horizontal strains North-North

uNE

horizontal strains North-East

uEN

horizontal strains East-North

uEE

horizontal strains East-East

Note

Units should be in km.

Note that vertical strain components can be obtained with following equations: uNZ = -uZN; uEZ = -uZE; uZZ = -(uEE + uNN)*NU/(1-NU);

Be careful about the definition of strike: seems that here the strike may be measured positive north of east, not east of north as stated in the documentation above.

Author(s)

Jonathan M. Lees<jonathan.lees@unc.edu>

References

Aki K., and P. G. Richards (1980) (ISBN-13: 978-1891389634) Quantitative seismology, Freemann & Co, New York.

Okada Y., Surface deformation due to shear and tensile faults in a half-space, Bull. Seismol. Soc. Am., 75:4, 1135-1154, 1985.

Acknowledgments: Francois Beauducel, Dmitry Nicolsky, University of Alaska

See Also

mogi1, mogiM

Examples

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library(RPMG)

EX = seq(from=-10, to=10, length=50)
WHY = seq(from=-10, to=10, length=50)
M = RPMG::meshgrid(EX, WHY )

OKout  = okada85(M$x, M$y,2,30,70,5,3,-45,1,1) 
old.par <- par(no.readonly = TRUE) 

par(mfrow=c(2, 2))

image(EX, WHY, OKout$uN, col=terrain.colors(100) ,
asp=1, main="uN" );contour(EX, WHY, OKout$uN, add=TRUE)

image(EX, WHY, OKout$uE, col=terrain.colors(100) ,
asp=1 , main="uE" );contour(EX, WHY, OKout$uE, add=TRUE)

image(EX, WHY, OKout$uZ, col=terrain.colors(100) ,
asp=1, main="uZ" );contour(EX, WHY, OKout$uZ,  add=TRUE)

plot(EX, OKout$uZ[, 25 ])


par(old.par)

geophys documentation built on May 1, 2019, 9:26 p.m.