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This table lists the header variables, their types, and descriptions.
They are grouped by category: required fields, time fields,
phase picks, instrument parameters,
station parameters, event parameters, misc.
The header types are defined in the second table.
Name | Type | Description |
---|---|---|
NPTS | N | Number of points per data component. [required] |
NVHDR | N |
Header version number. Current value is the integer 6. Older version data (NVHDR < 6) are automatically updated when read into sac. [required] |
B | F | Beginning value of the independent variable. [required] |
E | F | Ending value of the independent variable. [required] |
IFTYPE | I | Type of file [required]: = ITIME {Time series file} = IRLIM {Spectral file---real and imaginary} = IAMPH {Spectral file---amplitude and phase} = IXY {General x versus y data} = IXYZ {General XYZ (3-D) file} |
LEVEN | L | TRUE if data is evenly spaced. [required] |
DELTA | F | Increment between evenly spaced samples (nominal value). [required] |
ODELTA | F | Observed increment if different from nominal value. |
IDEP | I | Type of dependent variable: = IUNKN (Unknown) = IDISP (Displacement in nm) = IVEL (Velocity in nm/sec) = IVOLTS (Velocity in volts) = IACC (Acceleration in nm/sec/sec) |
SCALE | F | Multiplying scale factor for dependent variable [not currently used] |
DEPMIN | F | Minimum value of dependent variable. |
DEPMAX | F | Maximum value of dependent variable. |
DEPMEN | F | Mean value of dependent variable. |
NZYEAR | N | GMT year corresponding to reference (zero) time in file. |
NZJDAY | N | GMT julian day. |
NZHOUR | N | GMT hour. |
NZMIN | N | GMT minute. |
NZSEC | N | GMT second. |
NZMSEC | N | GMT millisecond. |
NZDTTM | N | GMT date-time array. Six element array equivalenced to NZYEAR, NZJDAY, NZHOUR, NZMIN, NZSEC, and NZMSEC. |
KZDATE | A | Alphanumeric form of GMT reference date. Derived from NZYEAR and NZJDAY. |
KZTIME | A | Alphanumeric form of GMT reference time. Derived from NZHOUR, NZMIN, NZSEC, and NZMSEC. |
IZTYPE | I | Reference time equivalence: = IUNKN (Unknown) = IB (Begin time) = IDAY (Midnight of refernece GMT day) = IO (Event origin time) = IA (First arrival time) = ITn (User defined time pick n, n=0,9) |
O | F | Event origin time (seconds relative to reference time.) |
KO | A | Event origin time identification. |
Phase Picks | ||
---|---|---|
A | F | First arrival time (seconds relative to reference time.) |
KA | K | First arrival time identification. |
F | F | Fini or end of event time (seconds relative to reference time.) |
KF | A | Fini identification. |
Tn | F | User defined time picks or markers, {\ai n}=0,9 (seconds relative to reference time). |
KT{\ai n} | K | A User defined time pick identifications, {\ai n}=0,9. |
Instrument Fields | ||
---|---|---|
KINST | K | Generic name of recording instrument. |
IINST | I | Type of recording instrument. [not currently used] |
RESPn | F | Instrument response parameters, n=0,9. [not currently used] |
Station Fields | ||
---|---|---|
KNETWK | K | Name of seismic network. |
KSTNM | K | Station name. |
ISTREG | I | Station geographic region. [not currently used] |
STLA | F | Station latitude (degrees, north positive) |
STLO | F | Station longitude (degrees, east positive). |
STEL | F | Station elevation (meters). [not currently used] |
STDP | F | Station depth below surface (meters). [not currently used] |
CMPAZ | F | Component azimuth (degrees clockwise from north). |
CMPINC | F | Component incident angle (degrees from vertical). |
KCMPNM | K | Component name. |
KSTCMP | A | Station component. Derived from KSTNM, CMPAZ, and CMPINC. |
LPSPOL | L | TRUE if station components have a positive polarity (left-hand rule). |
Event Fields | ||
---|---|---|
KEVNM | K | Event name. |
IEVREG | I | Event geographic region. [not currently used] |
EVLA | F | Event latitude (degrees, north positive). |
EVLO | F | Event longitude (degrees, east positive). |
EVEL | F | Event elevation (meters). [not currently used] |
EVDP | F | Event depth below surface (meters). [not currently used] |
MAG | F | Event magnitude. |
IMAGTYP | I | Magnitude type: = IMB (Bodywave Magnitude) = IMS (Surfacewave Magnitude) = IML (Local Magnitude) = IMW (Moment Magnitude) = IMD (Duration Magnitude) = IMX (User Defined Magnitude) |
IMAGSRC | I | Source of magnitude information: = INEIC (National Earthquake Information Center) = IPDE (Preliminary Determination of Epicenter) = IISC (Internation Seismological Centre) = IREB (Reviewed Event Bulletin) = IUSGS (US Geological Survey) = IBRK (UC Berkeley) = ICALTECH (California Institute of Technology) = ILLNL (Lawrence Livermore National Laboratory) = IEVLOC (Event Location (computer program) ) = IJSOP (Joint Seismic Observation Program) = IUSER (The individual using SAC2000) = IUNKNOWN (unknown) |
IEVTYP | I | Type of event: = IUNKN (Unknown) = INUCL (Nuclear event) = IPREN (Nuclear pre-shot event) = IPOSTN (Nuclear post-shot event) = IQUAKE (Earthquake) = IPREQ (Foreshock) = IPOSTQ (Aftershock) = ICHEM (Chemical explosion) = IQB (Quarry or mine blast confirmed by quarry) = IQB1 (Quarry/mine blast with designed shot info-ripple fired) = IQB2 (Quarry/mine blast with observed shot info-ripple fired) = IQBX (Quarry or mine blast - single shot) = IQMT (Quarry/mining-induced events: tremors and rockbursts) = IEQ (Earthquake) = IEQ1 (Earthquakes in a swarm or aftershock sequence) = IEQ2 (Felt earthquake) = IME (Marine explosion) = IEX (Other explosion) = INU (Nuclear explosion) = INC (Nuclear cavity collapse) = IO_ (Other source of known origin) = IL (Local event of unknown origin) = IR (Regional event of unknown origin) = IT (Teleseismic event of unknown origin) = IU (Undetermined or conflicting information) = IOTHER (Other) |
NEVID | N | Event ID (CSS 3.0) |
NORID | N | Origin ID (CSS 3.0) |
NWFID | N | Waveform ID (CSS 3.0) |
KHOLE | k | Hole identification if nuclear event. |
DIST | F | Station to event distance (km). |
AZ | F | Event to station azimuth (degrees). |
BAZ | F | Station to event azimuth (degrees). |
GCARC | F | Station to event great circle arc length (degrees). |
Miscellaneous Fields | ||
---|---|---|
LCALDA | L | TRUE if DIST, AZ, BAZ, and GCARC are to be calculated from station and event coordinates. |
IQUAL | I | Quality of data [not currently used]: = IGOOD (Good data) = IGLCH (Glitches) = IDROP (Dropouts) = ILOWSN (Low signal to noise ratio) = IOTHER (Other) |
ISYNTH | I | Synthetic data flag [not currently used]: = IRLDTA (Real data) = ????? (Flags for various synthetic seismogram codes) |
KDATRD | K | Date data was read onto computer. |
USER{\ai n} | F | User defined variable storage area, {\ai n}=0,9. |
KUSER{\ai n} | K | User defined variable storage area, {\ai n}=0,2. |
LOVROK | L | TRUE if it is okay to overwrite this file on disk. |
NXSIZE | N | Spectral Length (Spectral files only) |
NYSIZE | N | Spectral Width (Spectral files only) |
XMINIMUM | F | Minimum value of X (Spectral files only) |
XMAXIMUM | F | Maximum value of X (Spectral files only) |
YMINIMUM | F | Minimum value of Y (Spectral files only) |
YMAXIMUM | F | Maximum value of Y (Spectral files only) |
This table lists the header types and their definitions. The third
column lists the special value used to signify that a particular
header variable is undefined in a particular file.
Type | Definition | Undefined | Description |
---|---|---|---|
F | Floating | -12345.0 | Single precision. |
N | Integer | -12345 | Name begins with an ``N''. |
I | Enumerated | -12345 | Name begins with an ``I''. Has a limited set of integer values. Each value is given a specific name. Each value represents a specific condition. Subroutines use the equivalent alphanumeric name. |
L | Logical | FALSE Name begins with an ``L''. Value is either TRUE or FALSE. | |
K | Alphanumeric | ``-12345'' | Name begins with a ``K''. Either 8 or 16 characters long. |
A | Auxilary | Not really in the header. Derived from other header fields. |
The enumerated header field values are stored in the header as
integers. Their names and values are given in the table below.
Name | Value | Name | Value |
---|---|---|---|
itime | 01 | irlim | 02 |
iamph | 03 | ixy | 04 |
iunkn | 05 | idisp | 06 |
ivel | 07 | iacc | 08 |
ib | 09 | iday | 10 |
io | 11 | ia | 12 |
it0 | 13 | it1 | 14 |
it2 | 15 | it3 | 16 |
it4 | 17 | it5 | 18 |
it6 | 19 | it7 | 20 |
it8 | 21 | it9 | 22 |
iradnv | 23 | itannv | 24 |
iradev | 25 | itanev | 26 |
inorth | 27 | ieast | 28 |
ihorza | 29 | idown | 30 |
iup | 31 | illlbb | 32 |
iwwsn1 | 33 | iwwsn2 | 34 |
ihglp | 35 | isro | 36 |
inucl | 37 | ipren | 38 |
ipostn | 39 | iquake | 40 |
ipreq | 41 | ipostq | 42 |
ichem | 43 | iother | 44 |
igood | 45 | iglch | 46 |
idrop | 47 | ilowsn | 48 |
irldta | 49 | ivolts | 50 |
ixyz | 51 | imb | 52 |
ims | 53 | iml | 54 |
imw | 55 | imd | 56 |
imx | 57 | ineic | 58 |
ipde | 59 | iisc | 60 |
ireb | 61 | iusgs | 62 |
ibrk | 63 | icaltech | 64 |
illnl | 65 | ievloc | 66 |
ijsop | 67 | iuser | 68 |
iunknown | 69 | iqb | 70 |
iqb1 | 71 | iqb2 | 72 |
iqbx | 73 | iqmt | 74 |
ieq | 75 | ieq1 | 76 |
ieq2 | 77 | ime | 78 |
iex | 79 | inu | 80 |
inc | 81 | io_ | 82 |
il | 83 | ir | 84 |
it | 85 | iu | 86 |
This page maintained by:
peterg@llnl.gov -- Peter Goldstein
LLNL Disclaimer
8/12/98
UCRL-MA-112836