JSAC.seis {RSEIS}

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

Examples

## Not run: 


####  this will return a list of traces
Lname  <-  list.files(path='/data/wadati/bourbon/LaurelCanNC/R005.01' ,
 pattern="08.005.01.41.23.9024", full.names=TRUE)

S1   <-  JSAC.seis(Lname, Iendian = 1, PLOT = -1)


#####################   from a data base example: this will return one
#####                    trace header
f1  <-  DB$fn[200]

j1  <-  JSAC.seis(f1, Iendian=1, HEADONLY=TRUE , BIGLONG=FALSE, PLOT=-1)

print( j1[[1]]$HEAD )


#############   example for SEGY data: one SEGY  header

dir  <-  "/data/wadati/soju/SEISMIC_DATA/Reventador2005/rev05/SEGY/R251.01"
lf  <-  list.files(path=dir, pat="05.251", full.names=TRUE)
f1  <-  lf[1]
j1  <-  JSEGY.seis(f1, Iendian=1, HEADONLY=TRUE , BIGLONG=FALSE, PLOT=-1)


print( j1[[1]]$HEAD )


## End(Not run)