GET.seis: Reads various seismic file formats

In RSEIS: Seismic Time Series Analysis Tools

Reads various seismic file formats

Description

This fuction calls binary routines to read in ‘segy’, ‘sac’.

Usage

GET.seis(fnames, kind = 1, Iendian=1, BIGLONG=FALSE ,
HEADONLY=FALSE,  PLOT = -1, RAW=FALSE)

JGET.seis(fnames, kind = 1, Iendian=1, BIGLONG=FALSE ,
HEADONLY=FALSE,  PLOT = -1, RAW=FALSE)

Arguments

fnames	list of file names.
kind	an integer -1, 0, 1, 2 ; 0="RDATA" , -1="RDS", 0="RDATA", 1 = "segy", 2 = "sac", see notes below
Iendian	vector, Endian-ness of the data: 1,2,3: "little", "big", "swap". Default = 1 (little)
BIGLONG	logical, TRUE=long=8 bytes
HEADONLY	logical, TRUE= header information only; not seismic trace will be returned (runs a little faster).
PLOT	integer, <0 no plot; 0 interactive; >0 number of seconds to sleep
RAW	logical, default=FALSE(convert to volts) , TRUE (return counts intead of volts)

Details

"kind" can be numeric or character: options are 'RDS', 'RDATA', 'SEGY', 'SAC', corresponding to (-1, 0, 1, 2).

Uses readBin to extract data in SAC/SEGY format. User must know what kind of machine the data was created on for I/O purposes.

If data was created on a little endian machine but is being read on big endian machine, need to call the endian "swap" for swapping.

Iendian can be a vector if input files have different endian-ness.

If data was created on a machine with LONG=4 bytes, be sure to call the program with BIGLONG=FALSE.

The data returned is a list of lists, each element is one trace not necessarily related to the other traces in the list.

Once the data is read in, use prepSEIS to reformat the data into a list more amenable to further analysis in RSEIS.

See examples below for different cases.

Value

List containing the seismic data and header information. Each trace consists of a list with:

fn	original file name
sta	station name
comp	compnent
dt	delta t in seconds
DATTIM	time list
yr	year
jd	julian day
mo	month
dom	day of month
hr	hour
mi	minute
sec	sec
msec	milliseconds
dt	delta t in seconds
t1	time start of trace
t2	time end of trace
off	off-set
N	number of points in trace
units	units
amp	vector of trace values

Note

The easiext way to process datais to convert the data to an R-format type, using either save (kind=0) or saveRDS (kind=-1). If these are used then I/O is simple.

OLDER:

Information in the file names is ignored, so be sure to modify headers prior to using this method of extracting meta-data. (Or modify the meta data from the file names after reading in the data.)

For SEGY files, in LINUX-UNIX, use: rename, segymod (PASSCAL) to modify the headers

JGET.seis extracts digital seismic data from binary files stored in the file system. The program uses readBin for I/O and passes data back to R. Currently SAC, SEGY formats are installed but it is easy to extend. AH format is available for LINUX systems, but there were problems compiling in WINDOWS and MACOS so this feature was removed.

A filter for mseed format is currently being developed. Could use package 'IRISSeismic'

Author(s)

Jonathan M. Lees <[e-mail]>

See Also

plotJGET, JSAC.seis , prepSEIS, Mine.seis

Examples

data(GH)

DD = data.frame(GH$info)

#### get only vertical traces
WV = which( GH$COMPS=='V' )
L1 = length(WV)

GIVE = vector(mode='list')

for(j in 1:L1 )
{
    i = WV[j]
    AA = DD[i,]
    GIVE[[j]] = list(fn = AA$fn, sta =GH$STNS[i] , comp = GH$COMP[i], 
                     dt = AA$dt, DATTIM = AA, N = AA$n1, units = NA, 
                     coords = NA, amp = GH$JSTR[[i]]  )
}
#### par(mfrow=c(length(GIVE) , 1) )
#   for(i in 1:length(GIVE) ) { plotGH(GIVE[[i]])   }
tdir = tempdir()
for(i in 1:length(GIVE) )
{
    sig = GIVE[[i]]
  d1 =  dateStamp(sig$DATTIM, sep='_')
   nam1 =  paste(d1,sig$sta, sig$comp, sep='_')
    nam2 = paste0(nam1, '.RDS')
    nam3 = paste(tdir, nam2, sep='/')
    saveRDS(file=nam3, sig) 
    }
########################  Now  read files and make the DataBase:
LF  = list.files(path=tdir,pattern='.RDS',  full.names=TRUE)


Gseis = GET.seis(LF, kind = -1, Iendian=1, BIGLONG=FALSE ,
HEADONLY=FALSE,  PLOT = -1, RAW=FALSE)

zed <- prepSEIS(Gseis)

####   plot the data, and interact with the data
swig(zed, sel=which(zed$COMPS=='V'),  SHOWONLY=0)

if(interactive()){ plotJGET(Gseis) }

###   for data created on UNIX (SUN) but read on linux:
###   S1   <-  GET.seis(Lname, kind = 1, Iendian="swap", BIGLONG=FALSE, PLOT = -1)

###   for data created on linux (32 bit)  but read on linux 64 bit:
###  S1   <-  GET.seis(Lname, kind = 1, Iendian="little", BIGLONG=FALSE, PLOT = -1)

###   for SEGY data created on linux (64 bit)  but read on linux 32 bit:
###  S1   <-  GET.seis(Lname, kind = 1, Iendian="little", BIGLONG=TRUE, PLOT = -1)


###   for SAC data created on MAC-OS (64 bit)  but read on linux 32 bit:
###  S1   <-  GET.seis(Lname, kind = 2, Iendian="swap", BIGLONG=TRUE, PLOT = -1)

RSEIS documentation built on Sept. 13, 2024, 1:09 a.m.