grotseis: Get seismic rotation matrix

Description

Set up a rotation matrix for a seismic trace. Rotation matrix is 3D, although this rotation only creates a rotation for conversion to radial-transverse orientation.

Usage

grotseis(ang, flip = FALSE)

Arguments

ang

Angle to rotate horizontal components, degrees

flip

Logical, TRUE=flip the vertical axis, default=FALSE

Value

3 by 3 rotation matrix.

Details

Returns a 3 by 3 matrix used for rotationg a 3-component seismic record, usually stored as an N by 3 matrix. Only the N-E components are rotated, North component is assumed to be in position 2 and the east compnent is assumed to be in position 3. The vertical component can be flipped.

Examples

Run this code

STAXY=list()

STAXY$'x'=c(-2.9162198461534,-2.49599248511068,-2.85909405321704,-1.96135073099434,
-6.50413342506259,2.64026676599765,
-3.95701139503518,-2.84082134537436,-0.0457817300378462,-2.74214190991955)
STAXY$'y'=c(-7.83435541676815,-4.46180337254565,-6.46036190991833,-5.01212763828746,
-2.56091416028758,
5.31173503708142,2.10545324503380,-0.87490923667824,-0.172422188354707,-1.52055218789877)

STAXY$'lat'=c(14.685621984127,14.7159182222222,14.6979647030651,14.710975070028,
14.7329873333333,14.8037143111518
,14.7749104943935,14.7481391460905,14.7544511215933,14.7423394025875)

STAXY$'lon'=c(268.420918730159,268.424817925926,268.421447725096,268.429783940243,268.387586722222,
268.472531954619,268.41123843527,268.421611351166,268.447574716981,268.422528671994)

STAXY$'z'=c(0.92522857142857,1.48225333333333,1.14740517241379,1.4423781512605,1.51148,
2.53268681318681,2.70014678899083,2.04094444444444,2.90827547169811,2.31817123287671)

STAXY$'cen'=c(14.756,-91.552)

STAXY$name=c('OBS','CAR','MAR','CAS','MTB','STA','STE','MOT','SUM','DOM')
sguitoXY=list()
sguitoXY$'x'=c(-1.78551922571555)
sguitoXY$'y'=c(-1.80850340813817)
sguitoXY$'lat'=c(14.7397535236)
sguitoXY$'lon'=c(268.4314147874)
sguitoXY$'z'=c(2.501)

DAZ = distaz(STAXY$lat, STAXY$lon, sguitoXY$lat, sguitoXY$lon)

STAXY$az = DAZ$baz

plot(STAXY$x, STAXY$y, asp=1, xaxs="r"  , yaxs="r" )

text(STAXY$x, STAXY$y,STAXY$name, pos=3)

points(0,0, pch=3)
points(sguitoXY$x,sguitoXY$y , pch=8)

segments(sguitoXY$x, sguitoXY$y, STAXY$x, STAXY$y, col="green", lty=2)

vecs  = rbind(c(0,0,1), c(0,1,0))

for( i in 1:length(STAXY$x))
  {
rbaz = grotseis(STAXY$az[i], flip=FALSE)
bvec  = vecs##############   red is north, blue east
########  red is radial positive away from source, blue is transverse
##########   blue is positive to the right, if facing away from source
## arrows(STAXY$x[i],STAXY$y[i], STAXY$x[i]+vecs[,2], STAXY$y[i]+vecs[,3], col=c("red", "blue"), lty=2)
arrows(STAXY$x[i],STAXY$y[i], STAXY$x[i]+bvec[,2], STAXY$y[i]+bvec[,3], col=c("red", "blue"))

}