Rquake (version 2.5-1)

Vlocate: 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)

Value

list:

EQ

Hypocenter lcoation

ERR

Error Analysis

its

number of iteration

Ksolutions

list of matrices, each with intermediate x,y,z,t locations

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

Author

Jonathan M. Lees<[e-mail]>

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.

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)