Strike of the plate boundary projected on data point — projected_pb

The fault's strike in the PoR CRS projected on the data point along the predicted stress trajectories.

Usage

projected_pb_strike(x, PoR, pb, tangential = FALSE, ...)

Arguments

x, pb: sf objects of the data points and the plate boundary geometries in the geographical coordinate system
PoR: Pole of rotation. "data.frame" or object of class "euler.pole" containing the geographical coordinates of the Euler pole
tangential: Logical. Whether the plate boundary is a tangential boundary (TRUE) or an inward and outward boundary (FALSE, the default).
...: optional arguments passed to smoothr::densify()

Value

Numeric vector of the strike direction of the plate boundary (in degree)

Details

Useful to calculate the beta angle, i.e. the angle between SHmax direction (in PoR CRS!) and the fault's strike (in PoR CRS). The beta angle is the same in geographical and PoR coordinates.

Note

The algorithm calculates the great circle bearing between line vertices. Since transform plate boundaries represent small circle lines in the PoR system, this great-circle azimuth is only a approximation of the true (small-circle) azimuth.

Examples

data("nuvel1")
na_pa <- subset(nuvel1, nuvel1$plate.rot == "na")

data("plates")
plate_boundary <- subset(plates, plates$pair == "na-pa")

data("san_andreas")
res <- projected_pb_strike(
  x = san_andreas, PoR = na_pa, pb = plate_boundary, tangential = TRUE
)
head(res)
#> [1] 84.78438 89.40693 81.54405 83.80421 75.27521 83.81087
head(san_andreas$azi - res) # beta angle
#> [1] -48.78438 -82.40693  87.45595 -82.80421 -52.27521  76.18913