JSAC.seis: JSAC.seis

In RSEIS: Seismic Time Series Analysis Tools

JSAC.seis

Description

Read SEGY/SAC format binary data

Usage

JSAC.seis(fnames, Iendian = 1 , HEADONLY=FALSE,
BIGLONG=FALSE, PLOT = -1, RAW=FALSE)
JSEGY.seis(fnames, Iendian = 1 , HEADONLY=FALSE,
BIGLONG=FALSE, PLOT = -1, RAW=FALSE)

Arguments

fnames	vector of file names to be extracted and converted.
Iendian	vector, Endian-ness of the data: 1,2,3: "little", "big", "swap". Default = 1 (little)
HEADONLY	logical, TRUE= header information only
BIGLONG	logical, TRUE=long=8 bytes
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

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

For SEGY data the program is the same, although SEGY data does not have the problem of the BIGLONG so that is ignored.

For either code, a full header is returned, although the header for each format may be different.

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
HEAD	Full header as a data-frame of values (mixture of float and character strings)
N	Number of samples in trace
units	Units of samples, possibly: counts, volts, s, m/s, Pa, etc
IO	list: kind, Iendian, BIGLONG flags for I/O

Note

SAC created on PC (windows) or LINUX machines typically will be in little endian format. SAC created on a SUN will be in big endian format. If you want to swap endian-ness , choose swap.

MAC uses different convention.

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

SAC inserts -12345 for no data.

There are other issues regarding the size of long.

The units are often questionable and depend on the processing. The user should be careful and check to see that the proper conversions and multipliers have been applied.

Author(s)

Jonathan M. Lees<[e-mail]>

See Also

Mine.seis, rseis2sac

Examples

#####  make some SAC files, then read them in
data(GH)
apath = tempdir()
##  setwd(apath)
## apath = 'TEMP'
J =  rseis2sac(GH, sel =1:5,  path = apath, BIGLONG =FALSE )

####### next read them in
Lname  <-  list.files(path=J , pattern='SAC', full.names=TRUE)

S1   <-  JSAC.seis(Lname, Iendian = .Platform$endian, BIGLONG =FALSE ,  PLOT = -1)

####  check just the first one
i = 1
  plotGH(S1[[i]])

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