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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
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8/12/98
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