eseis (version 0.6.0)

spatial_distance: Calculate topography-corrected distances for seismic waves.

Description

The function calculates topography-corrected distances either between seismic stations or from seismic stations to pixels of an input raster.

Usage

spatial_distance(
  stations,
  dem,
  topography = TRUE,
  cores = 1,
  dmap = TRUE,
  dstation = TRUE,
  aoi
)

Value

List object with distance maps list and station distance matrix.

Arguments

stations

Numeric matrix of length two, x- and y-coordinates of the seismic stations to be processed (column-wise orgnaised).The coordinates must be in metric units, such as the UTM system and match with the reference system of the dem.

dem

raster object, the digital elevation model (DEM) to be processed. The DEM must be in metric units, such as the UTM system and match with the reference system of the coordinates of stations. See raster for supported types and how to read these to R.

topography

Logical scalar, option to enable topography correction, default is TRUE.

cores

Numeric scalar, number of CPU cores to use, only relevant for multicore computers. Default is 1.

dmap

Logical scalar, option to enable/disable calculation of distance maps. Default is TRUE.

dstation

Logical scalar, option to enable/disable calculation of interstation distances. Default is TRUE.

aoi

Numeric vector of length four, bounding coordinates of the area of interest to process, in the form c(x0, x1, y0, y1). Only implemented for single core mode (i.e., cores = 1).

Author

Michael Dietze

Details

Topography correction is necessary because seismic waves can only travel on the direct path as long as they are within solid matter. When the direct path is through air, the wave can only travel along the surface of the landscape. The function accounts for this effect and returns the corrected travel distance data set.

Examples

if (FALSE) {
## load and aggregate example DEM
data("volcano")
dem <- raster::raster(volcano)
dem <- raster::aggregate(x = dem, 2) * 10
dem@extent <- dem@extent * 1000
dem@extent <- dem@extent + c(510, 510, 510, 510)

## define example stations
stations <- cbind(c(200, 700), c(220, 700))

## plot example data
raster::plot(dem)
points(stations[,1], stations[,2])

## calculate distance matrices and stations distances
D <- spatial_distance(stations = stations, 
                      dem = dem, 
                      topography = TRUE, 
                      cores = 1)

## plot distance map for station 2
raster::plot(D$maps[[2]])

## show station distance matrix
print(D$stations)

## run with small aoi
D <- spatial_distance(stations = stations, 
                      dem = dem, 
                      topography = TRUE, 
                      cores = 1, 
                      aoi = c(400, 600, 600, 800))
}