SEG-Y Format - Archive of Digital Boomer Seismic Reflection Data Collected During USGS Field Activities 93LCA01 and 94LCA01 in Kingsley, Orange, and Lowry Lakes, Northeast Florida, 1993 and 1994

The seismic data are stored in SEG-Y, integer, Motorola format. The SEG-Y files on this disc conform to the SEG-Y standard format (Barry and others, 1975), with the exception of the 3,600-byte reel identification header that is in ASCII format. Standard SEG-Y uses an EBCDIC 3,600-byte reel identification header. The Delph Seismic version of SEG-Y consists of the following:

A 3,600-byte reel identification header, with the first 3,200 bytes consisting of an ASCII header block and a 400-byte binary header block. Both headers include information specific to the line and reel number.

The trace data block follows the reel identification header. The first 240 bytes of each trace block are the binary trace identification header. The seismic data samples follow the trace identification header.

Byte Numbers	Header Value Description
3201 - 3204	Job identification number.
3205 - 3208	Line number.
3209 - 3212	Reel number.
3213 - 3214	Number of data traces per record.
3215 - 3216	Number of auxiliary traces per record.
3217 - 3218	Sample interval, microseconds, this file (reel).
3219 - 3220	Sample interval, microseconds, original field recording.
3221 - 3222	Number of samples per data trace, this file (reel).
3223 - 3224	Number of samples per data trace, original field recording.
3225 - 3226	Data sample format code: 1 = floating point (4 bytes) 2 = fixed point (4 bytes) 3 = fixed point (2 bytes) 4 = fixed point with gain code (4 bytes).
3227 - 3228	CDP fold.
3229 - 3230	Trace sorting code: 1 = as recorded (no) sorting) 2 = CDP ensemble 3 = single fold continuous profile 4 = horizontally stacked.
3231 - 3232	Vertical sum code: 1 = no sum 2 = two sum ... N = N sum (N = 32,767).
3233 - 3234	Sweep frequency at start.
3235 - 3236	Sweep frequency at end.
3237 - 3238	Sweep length, ms.
3239 - 3240	Sweep type code: 1 = linear 2 = parabolic 3 = exponential 4 = other.
3241 - 3242	Trace number of sweep channel.
3243 - 3244	Sweep trace taper length, ms, at start if tapered.
3245 - 3246	Sweep trace taper length, ms, at end.
3247 - 3248	Taper type: 1 = linear 2 = cos 3 = other.
3249 - 3250	Correlated data traces: 1 = no 2 = yes.
3251 - 3252	Binary gain recovered: 1 = yes 2 = no.
3253 - 3254	Amplitude recovery method: 1 = none 2 = spherical divergence 3 = AGC 4 = other.
3255 - 3256	Measurement system: 1 = meters 2 = feet.
3257 - 3258	Impulse signal: 1 = Upward = negative number. 2 = Upward = positive number.
3259 - 3260	Vibratory polarity code - seismic signal lags pilot signal by: 1 = 337.5 - 22.5 degrees 2 = 22.5 - 67.5 degrees 3 = 67.5 - 112.5 degrees 4 = 112.5 - 157.5 degrees 5 = 157.5 - 202.5 degrees 6 = 202.5 - 247.5 degrees.

Byte Numbers

Header Value Description

3201 - 3204

Job identification number.

3205 - 3208

Line number.

3209 - 3212

Reel number.

3213 - 3214

Number of data traces per record.

3215 - 3216

Number of auxiliary traces per record.

3217 - 3218

Sample interval, microseconds, this file (reel).

3219 - 3220

Sample interval, microseconds, original field recording.

3221 - 3222

Number of samples per data trace, this file (reel).

3223 - 3224

Number of samples per data trace, original field recording.

3225 - 3226

Data sample format code: 1 = floating point (4 bytes) 2 = fixed point (4 bytes) 3 = fixed point (2 bytes) 4 = fixed point with gain code (4 bytes).

3227 - 3228

CDP fold.

3229 - 3230

Trace sorting code: 1 = as recorded (no) sorting) 2 = CDP ensemble 3 = single fold continuous profile 4 = horizontally stacked.

3231 - 3232

Vertical sum code: 1 = no sum 2 = two sum ... N = N sum (N = 32,767).

3233 - 3234

Sweep frequency at start.

3235 - 3236

Sweep frequency at end.

3237 - 3238

Sweep length, ms.

3239 - 3240

Sweep type code: 1 = linear 2 = parabolic 3 = exponential 4 = other.

3241 - 3242

Trace number of sweep channel.

3243 - 3244

Sweep trace taper length, ms, at start if tapered.

3245 - 3246

Sweep trace taper length, ms, at end.

3247 - 3248

Taper type: 1 = linear 2 = cos 3 = other.

3249 - 3250

Correlated data traces: 1 = no 2 = yes.

3251 - 3252

Binary gain recovered: 1 = yes 2 = no.

3253 - 3254

Amplitude recovery method: 1 = none 2 = spherical divergence 3 = AGC 4 = other.

3255 - 3256

Measurement system: 1 = meters 2 = feet.

3257 - 3258

Impulse signal: 1 = Upward = negative number. 2 = Upward = positive number.

3259 - 3260

Vibratory polarity code - seismic signal lags pilot signal by: 1 = 337.5 - 22.5 degrees 2 = 22.5 - 67.5 degrees 3 = 67.5 - 112.5 degrees 4 = 112.5 - 157.5 degrees 5 = 157.5 - 202.5 degrees 6 = 202.5 - 247.5 degrees.

Byte Numbers	Header Value Description
1 - 4	Trace sequence number within line.
5 - 8	Trace sequence number within file (reel).
9 - 12	Original field record number.
13 - 16	Trace number within original field record.
17 - 20	Energy source point number.
21 - 24	CDP ensemble number.
25 - 28	Trace number within the CDP ensemble.
29 - 30	Trace identification code: 1 = seismic data.
31 - 32	Number of vertically summed traces yielding this trace.
33 - 34	Number of horizontally stacked traces yielding this trace.
35 - 36	Data use: 1 = production 2 = test.
37 - 40	Distance from source point to receiver group.
41 - 44	Receiver group elevation - above sea level are positive, below sea level are negative.
45 - 48	Surface elevation at source.
49 - 52	Source depth below surface (positive number).
53 - 56	Datum elevation at receiver group.
57 - 60	Datum elevation at source.
61 - 64	Water depth at source (this is the fish depth below the sea surface in meters*10).
65 - 68	Water depth at group.
69 - 70	Scalar to be applied to all elevations & depths, specified in bytes 41 - 68 to give the real value. Scalar = 1, +/-10, +/-100, +/-1000, or +/-10,000. If positive, scalar is used as a multiplier; if negative, scalar is used as a divisor.
71 - 72	Scalar to be applied to all coordinate specified in bytes 73 - 88 to give the real value. Scalar = 1, +/-10, +/-100, +/-1000, or +/-10,000. If positive, scalar is used as a multiplier; if negative, scalar is used as a divisor.
73 - 76	Source coordinate - X. UTM Easting coordinate or longitude.
77 - 80	Source coordinate - Y. UTM Northing coordinate or latitude.
81 - 84	Group coordinate - X. UTM Easting coordinate or longitude.
85 - 88	Group coordinate - Y. UTM Northing coordinate or latitude.
89 - 90	Coordinate units: 1 = length (meters or feet) 2 = seconds of arc.
91 - 92	Weathering velocity.
93 - 94	Subweathering velocity.
95 - 96	Uphole time at source.
97 - 98	Uphole time at group.
99 - 100	Source static correction.
101 - 102	Group static correction.
103 - 104	Total static applied.
105 - 106	Lag time A. Time in ms between end of 240-byte trace identification header and time break. Positive if time break occurs after end of header, negative if time break occurs before end of header. Time break is defined as the initiation pulse which may be recorded on an auxiliary trace or as otherwise specified by the recording system.
107 - 108	Lag time B. Time in ms between the time break and positive or negative.
109 - 110	Delay recording time. Time in ms between initiation time of energy source and time when recording of data samples begins.
111 - 112	Mute time - start.
113 - 114	Mute time - end.
115 - 116	Number of samples in this trace.
117 - 118	Sample interval, in microseconds, for this trace.
119 - 120	Gain type of field instruments: 1 = fixed, 2 = binary, 3 = floating point, 4 = --- N = optional use.
121 - 122	Instrument gain constant.
123 - 124	Instrument early or initial gain (db).
125 - 126	Correlated: 1 = no 2 = yes.
127 - 128	Sweep frequency at start.
129 - 130	Sweep frequency at end.
131 - 132	Sweep length, ms.
133 - 134	Sweep type: 1 = linear 2 = parabolic 3 = exponential 4 = other.
135 - 136	Sweep trace taper length at start, ms.
137 - 138	Sweep trace taper length at end, ms.
139 - 140	Taper type: 1 = linear 2 = cos 3 = other.
141 - 142	Alias filter frequency.
143 - 144	Alias filter slope.
145 - 146	Notch filter frequency.
147 - 148	Notch filter slope.
149 - 150	Low cut frequency.
151 - 152	High cut frequency.
153 - 154	Low cut slope.
155 - 156	High cut slope.
157 - 158	Year data recorded (four digit integer).
159 - 160	Day of year.
161 - 162	Hour of day (24 hour clock).
163 - 164	Minute of hour.
165 - 166	Second of minute.
167 - 168	Time basis code: 1 = local 2 = GMT 3 = other.
169 - 170	Trace weighting factor - defined as 2-N volts for the least significant bit (N=0, 1,...,32,767).
171 - 172	Geophone group number of roll switch position one.
173 - 174	Geophone group number of trace number one within original field record.
175 - 176	Geophone group number of last trace within original field record.
177 - 178	Gape size (total number of groups dropped).
179 - 180	Overtravel associated with taper at beginning or end of line: 1 = down (or behind) 2 = up (or ahead).
181 - 240	Unassigned - for optional information.

Byte Numbers

Header Value Description

1 - 4

Trace sequence number within line.

5 - 8

Trace sequence number within file (reel).

9 - 12

Original field record number.

13 - 16

Trace number within original field record.

17 - 20

Energy source point number.

21 - 24

CDP ensemble number.

25 - 28

Trace number within the CDP ensemble.

29 - 30

Trace identification code: 1 = seismic data.

31 - 32

Number of vertically summed traces yielding this trace.

33 - 34

Number of horizontally stacked traces yielding this trace.

35 - 36

Data use: 1 = production 2 = test.

37 - 40

Distance from source point to receiver group.

41 - 44

Receiver group elevation - above sea level are positive, below sea level are negative.

45 - 48

Surface elevation at source.

49 - 52

Source depth below surface (positive number).

53 - 56

Datum elevation at receiver group.

57 - 60

Datum elevation at source.

61 - 64

Water depth at source (this is the fish depth below the sea surface in meters*10).

65 - 68

Water depth at group.

69 - 70

Scalar to be applied to all elevations & depths, specified in bytes 41 - 68 to give the real value. Scalar = 1, +/-10, +/-100, +/-1000, or +/-10,000. If positive, scalar is used as a multiplier; if negative, scalar is used as a divisor.

71 - 72

Scalar to be applied to all coordinate specified in bytes 73 - 88 to give the real value. Scalar = 1, +/-10, +/-100, +/-1000, or +/-10,000. If positive, scalar is used as a multiplier; if negative, scalar is used as a divisor.

73 - 76

Source coordinate - X. UTM Easting coordinate or longitude.

77 - 80

Source coordinate - Y. UTM Northing coordinate or latitude.

81 - 84

Group coordinate - X. UTM Easting coordinate or longitude.

85 - 88

Group coordinate - Y. UTM Northing coordinate or latitude.

89 - 90

Coordinate units: 1 = length (meters or feet) 2 = seconds of arc.

91 - 92

Weathering velocity.

93 - 94

Subweathering velocity.

95 - 96

Uphole time at source.

97 - 98

Uphole time at group.

99 - 100

Source static correction.

101 - 102

Group static correction.

103 - 104

Total static applied.

105 - 106

Lag time A. Time in ms between end of 240-byte trace identification header and time break. Positive if time break occurs after end of header, negative if time break occurs before end of header. Time break is defined as the initiation pulse which may be recorded on an auxiliary trace or as otherwise specified by the recording system.

107 - 108

Lag time B. Time in ms between the time break and positive or negative.

109 - 110

Delay recording time. Time in ms between initiation time of energy source and time when recording of data samples begins.

111 - 112

Mute time - start.

113 - 114

Mute time - end.

115 - 116

Number of samples in this trace.

117 - 118

Sample interval, in microseconds, for this trace.

119 - 120

Gain type of field instruments: 1 = fixed, 2 = binary, 3 = floating point, 4 = --- N = optional use.

121 - 122

Instrument gain constant.

123 - 124

Instrument early or initial gain (db).

125 - 126

Correlated: 1 = no 2 = yes.

127 - 128

Sweep frequency at start.

129 - 130

Sweep frequency at end.

131 - 132

Sweep length, ms.

133 - 134

Sweep type: 1 = linear 2 = parabolic 3 = exponential 4 = other.

135 - 136

Sweep trace taper length at start, ms.

137 - 138

Sweep trace taper length at end, ms.

139 - 140

Taper type: 1 = linear 2 = cos 3 = other.

141 - 142

Alias filter frequency.

143 - 144

Alias filter slope.

145 - 146

Notch filter frequency.

147 - 148

Notch filter slope.

149 - 150

Low cut frequency.

151 - 152

High cut frequency.

153 - 154

Low cut slope.

155 - 156

High cut slope.

157 - 158

Year data recorded (four digit integer).

159 - 160

Day of year.

161 - 162

Hour of day (24 hour clock).

163 - 164

Minute of hour.

165 - 166

Second of minute.

167 - 168

Time basis code: 1 = local 2 = GMT 3 = other.

169 - 170

Trace weighting factor - defined as 2-N volts for the least significant bit (N=0, 1,...,32,767).

171 - 172

Geophone group number of roll switch position one.

173 - 174

Geophone group number of trace number one within original field record.

175 - 176

Geophone group number of last trace within original field record.

177 - 178

Gape size (total number of groups dropped).

179 - 180

Overtravel associated with taper at beginning or end of line: 1 = down (or behind) 2 = up (or ahead).

181 - 240

Unassigned - for optional information.