Vlocate: Hypocenter Determination

In Rquake: Seismic Hypocenter Determination

Hypocenter Determination

Description

Hypocenter Determination with error checking and adjustments.

Usage

Vlocate(Ldat,EQ,vel, 
                  distwt = 10,
                  lambdareg =100,
                  REG = TRUE,
                  WTS = TRUE,
                  STOPPING = TRUE,
                  tolx = 0.1,
                  toly = 0.1,
                  tolz = 0.5,
                  RESMAX = c(.4,.5),
                  maxITER = c(7, 5, 7, 4),
                  PLOT=FALSE)

Arguments

Ldat	list, must inlude: lat, lon ,err, sec, cor (see details)
EQ	list, must inlude: lat,lon,z, t
vel	list, 1D velocity structure
distwt	distance weighting factor
lambdareg	regularization parameter for damping
REG	logical, TRUE=use regularization
WTS	logical, TRUE==use weighting
STOPPING	logical, TRUE=use stopping criteria
tolx	numeric, tolerance in km in x direction
toly	numeric, tolerance in km in y direction
tolz	numeric, tolerance in km in z direction
RESMAX	vector, residual max for P and S, default=c(4,5)
maxITER	vector, Maximum number of iterations for each section of the location routine, default=c(7,5,7,4)
PLOT	logical, plot results during iterations

Details

This is a wrapper for XYlocate, only here the lat-lon of the stations is passed and the code does the projection internally.

There are 3 main loops, each controled by differing input params: first event is located only in XY keeping the depth fixed (7 iterations). Then an initial free solution is estimated using robust elimination of residual based on RESMAX (5 iterations). Finally a set of 7 iterations is applied providing the final estimate, along with error bars, elliposids, etc.

In the event no good solution is derived, the regularization parameter is doubled and a loop with 4 iterations is applied, and the result returned.

Value

list:

EQ	Hypocenter lcoation
ERR	Error Analysis
its	number of iteration
Ksolutions	list of matrices, each with intermediate x,y,z,t locations

Note

The schedule may be adjusted by duplicating this function and changing the maxit parameters.

Author(s)

Jonathan M. Lees<[e-mail]>

References

Lee and Stewart

See Also

XYlocate, Klocate, DoRLocate

Examples

library(RSEIS)
data(GH, package='RSEIS')

g1 = GH$pickfile

data(VELMOD1D, package='RSEIS')
vel= VELMOD1D

 w1 = which(!is.na(g1$STAS$lat))
         sec = g1$STAS$sec[w1]

         N = length(sec)
         Ldat =    list(
           name = g1$STAS$name[w1],
           sec = g1$STAS$sec[w1],
           phase = g1$STAS$phase[w1],
           lat=g1$STAS$lat[w1],
           lon = g1$STAS$lon[w1],
           z = g1$STAS$z[w1],
           err= g1$STAS$err[w1],
           yr = rep(g1$LOC$yr , times=N),
           jd = rep(g1$LOC$jd, times=N),
           mo = rep(g1$LOC$mo, times=N),
           dom = rep(g1$LOC$dom, times=N),
           hr =rep( g1$LOC$hr, times=N),
           mi = rep(g1$LOC$mi, times=N) )


wstart = which.min(Ldat$sec)
        EQ = list(lat=Ldat$lat[wstart], lon=Ldat$lon[wstart], z=6, t=Ldat$sec[wstart] )
      

  AQ = Vlocate(Ldat,EQ,vel, 
      distwt = 10,
      lambdareg =100 ,
      REG = TRUE,
      WTS = TRUE,
      STOPPING = TRUE,
      tolx =   0.01,
      toly = 0.01 ,
      tolz = 0.05, maxITER = c(7,5,7,4) , RESMAX = c(0.1, 0.1),  PLOT=FALSE)

Rquake documentation built on June 22, 2024, 11:54 a.m.