Acronyms and abbreviations

  • AGC – automatic gain control
  • CDP – Common Depth-point
  • CD-ROM – Compact Disc Read-Only Memory
  • CMP – Common Midpoint
  • DB – decibel
  • DMO – dip move-out
  • EBCDIC – Extended Binary Coded Decimal Interchange Code
  • EPS – Encapsulated PostScript Format
  • EPSG – European Petroleum Survey Group
  • FFT – Fast Fourier Transform
  • FIRE – Finnish Reflection Experiment
  • Gb – gigabyte
  • GTK – Geological Survey of Finland
  • Hz – hertz
  • IBM – International Business Machines Corporation
  • I/O – input/output
  • JPEG – Joint Photographic Experts Group
  • KKJ – kartastokoordinaattijärjestelmä (National Grid Coordinate System)
  • Km – kilometre
  • Mb – megabyte
  • NMO – normal move-out
  • RMS – root mean square
  • SEG-Y – Society for Exploration Geophysicists Y-format
  • SU – Seismic Un*x
  • TIFF – Tagged Image File Format
  • TWT – two-way travel time
  • UH – University of Helsinki

Coordinates

Coordinate system

The coordinate system of the data is the Finland Uniform Coordinate System (EPSG:2393). This is a projected coordinate reference system based on the Hayford ellipsoid (1924) and transverse Mercator projection, with the central meridian set along the 27th meridian east. This one grid zone covers the whole of Finland.

In Finnish, the coordinate system is known either as "Yhtenäiskoordinaattijärjestelmä" (YKJ) or "Kartastokoordinaattijärjestelmä, kaista 3" (KKJ3). These two abbreviations are occasionally used in OpenFIRE data files.

The false easting of the reference system is Y = 3 500 000 meters.

Common mid-point coordinates are also available in alternative geographical coordinates, located on the EUREF-FIN (ETRS89) datum.

Syntax of pole coordinate files

The coordinate units are in meters. As a convention, the X (bytes 73–76 or 81–84) in trace headers is the northing and Y (bytes 77–80 or 85–88) is the easting. Comment lines start with the symbol #, followed by the coordinates of each peg.

The coordinate files have 3 columns, from left to right POLEID (pole identifier number), X (northing in meters) and Y (easting in meters). The pole coordinates are given for each subdivision of line separately.

An example:

#  Pole coordinates for FIRE 3-1.
#  Units are in metres. Coordinate system KKJ3.
#  Format string: "%6d %11d %11d\n"
#
#  Fire 3-1 starts here
# POLEID  X(NORTHING) Y(EASTING)
     1     6975392     3591999
     2     6975408     3592046
     3     6975428     3592092
     4     6975448     3592138

Syntax of CMP coordinate files

The coordinate units in stacked data are in meters. As a convention, the X (bytes 73–76 or 81–84) in trace headers is the northing and Y (bytes 77–80 or 85–88) is the easting. Comment lines start with the symbol #, followed by the coordinates of each common mid-point.

The coordinate files have 3 columns, from left to right CMPID (common mid-point identifier number), X (northing in meters) and Y (easting in meters). The CMP coordinates are given for each subdivision of line separately.

An example:

#  CMP coordinates for FIRE 1-1.
#  Units are in metres. Coordinate system KKJ3.
#  Format string: "%6d %11d %11d\n"
#
#  Fire 1-1 starts here
# CMPID   X(NORTHING) Y(EASTING)
    10     7162587     3641460
    11     7162562     3641463
    12     7162537     3641466

Alternatively, the coordinate columns can be LATITUDE and LONGITUDE, given in decimal degrees on the EUREF-FIN datum.

An example:

#  CMP coordinates for FIRE 1-1.
#  Units are in decimal degrees (EUREF-FIN).
#  Format string: "%6d %10.6f %10.6f\n"
#
#  Fire 1-1 starts here
# CMPID  LATITUDE  LONGITUDE
    10  64.532124  29.944352
    11  64.531899  29.944390
    12  64.531674  29.944429