This code works for interpolation of horizontal velocities (or displacements).
It inputs a discretized velocity (or displacement) dataset, and has the options to
do the following:
1. check velocity data compatibility
2. interpolate velocity data and estimate velocities at given locations
3. interpolate velocity data and estimate translation, rotation, and strain rates
To run the program:
% visr < driver.file
Example 1: checking velocity compatibility
driver file content:
input file: velmap.dat .........! station coordinate and velocity data
output file: velmap.out ........! checking result
Parameters:
is_wght ...............! distance weighting scheme: 1=gaussian, 2=quadratic
id_wght ...............! density weightting scheme: 1=azimuth, 2=voronoi area
min_tau,max_tau,in_tau ! minimum, maximum, and incremental spatial smoothing constants (km)
wt0 ............................! weighting threshold
1 ..............................! for checking velocity compatibility
lonmin,lonmax,latmin,latmax ....! checking range (in degree)
ncrp ...........................! number of creep faults
crpf ...........................! creep fault data file
Example 2: velocity interpolation for velocities at given locations
driver file content (visr_vel.drv) :
input file: velh.cmm4 ..........! station coordinate and velocity data
output file: vel_intrp.out .....! interpolation result
is_wght ...............! distance weighting scheme: 1=gaussian, 2=quadratic
id_wght ...............! density weightting scheme: 1=azimuth, 2=voronoi area
min_tau,max_tau,in_tau ! minimum, maximum, and incremental spatial smoothing constants (km)
wt0 ............................! weighting threshold
2 ..............................! for velocity interpolation at sites
vel_intrp.dat ..................! site list for interpolation, format(a8,2f10.4) for sitename,longitude and latitude (in degree)
ncrp ...........................! number of creep faults
crpf ...........................! creep fault data file
Output Parameters:
Longitude, Latitude ............! location coordinates
vx, svx, vy, svy, cxy ..........! Vx, Vx_sig, Vy, Vy_sig, Corr_xy
dis ............................! smoothing distance
weight .........................! total data weighting
chisq ..........................! postfit residual chisquare
nsite ..........................! # of sites used
index = 1 ......................! not enough sites found within range
index = 2 ......................! site located outside of network
Example 3: velocity interpolation for rotation and strain rates
driver file content (visr.drv):
input file: velh.cmm4 ..........! station coordinate and velocity data
output file: visr.out ..........! interpolation result
is_wght ...............! distance weighting scheme: 1=gaussian, 2=quadratic
id_wght ...............! density weightting scheme: 1=azimuth, 2=voronoi area
min_tau,max_tau,in_tau ! minimum, maximum, and incremental spatial smoothing constants (km)
wt0 ............................! weighting threshold
unc_min ........................! cutoff uncertainty for velocity data input
3 ..............................! option for solution of rotation and strain rates
lonmin,lonmax,latmin,latmax,dlon,dlat ..! interpolation range and step (degree)
ncrp ...........................! number of creep faults
crpf ...........................! creep fault data file
Output Parameters:
Longitude, Latitude ............! location coordinates
vx+svx, vy+svy, cxy ............! Vx, Vx_sig, Vy, Vy_sig, Corr_xy
w+dw ...........................! rotation rate, clockwise positive
exx+dexx, exy+dexy, eyy+deyy ...! strain rates of Exx, Exy, Eyy and their uncertainties
emax+demax, emin+demin .........! Maximum and minimum principal strain rates and their uncertainties
shr+dshr, azi+dazi .............! maximum shear strain rate, its (dexmal) azimuthal direction measured clockwise from north, and their uncertainties; the azimuthal directions of the maximum and minimum principal strain rates are 45 degree counter-clockwise and clockwise from azi respectively
dilat+ddilat ...................! dilatation rate and its uncertainty
dis ............................! smoothing distance
weight .........................! total data weighting
chisq ..........................! postfit residual chisquare
nsite ..........................! # of sites used
index = 1 ......................! not enough sites found within range
index = 2 ......................! site located outside of network
The files:
visr.f : main Fortran program of visr
: voron.f90 : Fortran subroutine for Voronoi cell area calculation
visr.drv : driver file for strain and rotation interpolation
velh.cmm4 : CMM4 GPS velocity data for southern California
visr.out : output file of strain and rotation interpolation
crp.dat : creep fault segment data file
visr_vel.drv : driver file for velocity interpolation at given locations
vel_intrp.dat : input data file of interpolation site locations
vel_intrp.out : output file of velocity interpolation result