SUMMARY

Generates sample data files and stores them in memory.

SYNTAX

DATAGEN {MORE} {COMMIT|ROLLBACK|RECALLTRACE} {SUB  name} {filelist}

where SUB is a datagen subdirectory and * name" is one of the following:

LOCAL
REGIONAL
TELESEISEM
DEEP

INPUT

MORE:
Place the new sample data files in memory AFTER the old data. If this option is omitted, the new sample data files REPLACE the old ones.

Note:
if the MORE option is not specified, the COMMIT, ROLLBACK, and RECALLTRACE options have no effect.

COMMIT:
If the MORE option is specified, the COMMIT option commits headers and waveforms in SAC memory -- removing any previous versions of headers or waveforms from RAM -- prior to generating more files. COMMIT is the default.

ROLLBACK:
If the MORE option is specified, the ROLLBACK option reverts to the last committed version of the header and waveform before generating more files.

RECALLTRACE:
If the MORE option is specified, the RECALLTRACE option:

reverts to the last committed version of the waveform,

reverts to the last committed version of those header variables closely linked to the waveform,

commits those header variables which are loosely linked to the waveform. (use HELP RECALLTRACE for a list of which header variables are committed, and which are rolled back.)

SUB name:
Select the sub-directory name from which to read the data. Where the subdirectory name is local, regional, or teleseismic.

A filelist is required. Possible filenames are listed below.

name:
LOCAL|REGIONAL|TELESEIS | DEEP ,BREAK Specifics about the contents of these sub-directories is given below.

filelist:
Each SUBdirectory has SAC files from a single event. A filelist is one or more SAC files in SUB.

MORE:	Place the new sample data files in memory AFTER the old data. If this option is omitted, the new sample data files REPLACE the old ones.
Note:	if the MORE option is not specified, the COMMIT, ROLLBACK, and RECALLTRACE options have no effect.
COMMIT:	If the MORE option is specified, the COMMIT option commits headers and waveforms in SAC memory -- removing any previous versions of headers or waveforms from RAM -- prior to generating more files. COMMIT is the default.
ROLLBACK:	If the MORE option is specified, the ROLLBACK option reverts to the last committed version of the header and waveform before generating more files.
RECALLTRACE:	If the MORE option is specified, the RECALLTRACE option: reverts to the last committed version of the waveform, reverts to the last committed version of those header variables closely linked to the waveform, commits those header variables which are loosely linked to the waveform. (use HELP RECALLTRACE for a list of which header variables are committed, and which are rolled back.)
SUB name:	Select the sub-directory name from which to read the data. Where the subdirectory name is local, regional, or teleseismic. A filelist is required. Possible filenames are listed below.
name:	LOCAL\|REGIONAL\|TELESEIS \| DEEP ,BREAK Specifics about the contents of these sub-directories is given below.
filelist:	Each SUBdirectory has SAC files from a single event. A filelist is one or more SAC files in SUB.

DEFAULT VALUES

DATAGEN COMMIT SUB LOCAL cdv.z

DESCRIPTION

The DATAGUEN command operates much like the READ command except that for DATAGEN, any SAC file read into memory is from a subdirectory of ${SACHOME}/aux/datagen/SUB/. Help file TRAVELTIME includes runs that use DATAGEN.

LOCAL EVENT

The local event occurred in the Livermore Valley of California. It was a small unfelt event (ML 1.6). It was recorded by the Livermore Local Seismic Network (LLSN). LLSN is a set of vertical and three-component stations operated by LLNL and the USGS. Data from nine three-component stations are included in this set. There is 40 seconds of data sampled at 100 samples per second. Station information, event information, p-wave time picks, and coda picks are included in the headers. The filenames are:
cal.z, cal.n, cal.e
cao.z, cao.n, cao.e
cda.z, cda.n, cda.e
cdv.z, cdv.n, cdv.e
cmn.z, cmn.n, cmn.e
cps.z, cps.n, cps.e
cva.z, cva.n, cva.e
cvl.z, cvl.n, cvl.e
cvy.z, cvy.n, cvy.e

REGIONAL EVENT

The regional event occurred in Nevada and was recorded by the Digital Seismic Network (DSS). DSS is a set of four broadband three-component stations in the Western U.S. The stations are:

elk: Elko, NV

lac: Landers, CA

knb: Kanab, UT

mnv: Mina, NV

The sampling rate is 40 samples per second. The files contain 300 seconds of data, starting 5 seconds before the origin time of the event. The filenames are:
elk.z, elk.n, elk.e
lac.z, lac.n, lac.e
knb.z, knb.n, knb.e
mnv.z, mnv.n, mnv.e

elk:	Elko, NV
lac:	Landers, CA
knb:	Kanab, UT
mnv:	Mina, NV

TELESEISMIC EVENT

The teleseismic event occurred off the coast of Northern California near Eureka on September 10, 1984. It was a moderate to large event (ML 6.6, MB 6.1, MS 6.7) and was felt from the San Francisco Bay area to Roseburg, Oregon. It was recorded at the Regional Seismic Test Network (RSTN), a set of five stations in the U.S. and Canada. The stations are:

cpk: Tennessee

ntk: Northwest Territories, Canada

nyk: New York

onk: Ontario, Canada

sdk: South Dakota

Both mid-period and long period data is included. Data from cpk was not available and the long-period data from sdk is clipped. There is 1600 seconds of data in this set. The long-period data was recorded at 1 sample per second and the mid-period data at 4 samples per second:
ntkl.z, ntkl.n, ntkl.e, ntkm.z, ntkm.n, ntkm.e
nykl.z, nykl.n, nykl.e, nykm.z, nykm.n, nykm.e
onkl.z, onkl.n, onkl.e, onkm.z, onkm.n, onkm.e
sdkl.z, sdkl.n, sdkl.e, sdkm.z, sdkm.n, sdkm.e

cpk:	Tennessee
ntk:	Northwest Territories, Canada
nyk:	New York
onk:	Ontario, Canada
sdk:	South Dakota

DEEP EVENT

(new in SAC v102.0) The seismograms in DEEP are from the Sakhalin Island Event (May 12, 1990; M=6.5; Depth=611 km). The phases are very impulsive, and one can see many converted phases. There are vertical-, radial-, and transverse-component waveforms from eight broadband stations. The filenames are:
bla.r bla.t bla.z
ccm.r ccm.t ccm.z
cor.r cor.t cor.z
hrv.r hrv.t hrv.z
kev.r kev.t kev.z
kip.r kip.t kip.z
pas.r pas.t pas.z
tol.r tol.t tol.z
This data set was created as part of a focal-mechanism study, which used the polarity and amplitudes of the SV and SH phases. Horizontal components for a three-component seismograph must be rotated from North-South and East-West into Radial and Transverse to separate SV from SH. Positive Radial is forward and positive Transverse is to the right with respect to an observer facing the station on the epicenter-station line. To verify this:
SAC> datagen sub deep kev.*
  /usr/local/sac/aux/datagen/deep/kev.r ...kev.t ...kev.z
SAC> lh baz cmpaz
  FILE: /usr/local/sac/aux/datagen/deep/kev.r - 1
  baz = 4.882252e+01                    cmpaz = 2.288225e+02
  FILE: /usr/local/sac/aux/datagen/deep/kev.t - 2
  baz = 4.882252e+01                    cmpaz = 3.188225e+02
  FILE: /usr/local/sac/aux/datagen/deep/kev.z - 3
  baz = 4.882252e+01                    cmpaz = 0.000000e+00
SAC>
For the Radial direction, the cmpaz is in the opposition direction of the back azimuth, and, as discussed in ROTATE, the Transverse is 90 degrees more than the Radial.

ERROR MESSAGES

1301: No data files read in.
- haven't given a list of files to read.
- none of the files in the list could be read.
1314: Data file list can't begin with a number.
1315: Maximum number of files in data file list is

WARNING MESSAGES

0101: opening file
0108: File does not exist:
0114: reading file
- Normally when SAC encounters one of these errors it skips that file and reads the remainder. These errors can be made to be fatal using the READERR command.

LATEST REVISION

Version 102.0 (2020)