Reflection Seismology Final Project
By William Cross Torsch
Louisiana State University
Department of Geology and Geophysics
1. Delete Bad Traces
SUKILL file_num.su > file_num.kill.su min=(first trace to kill) count=(number of traces to kill)
Step 1: View each file using a wiggle plot: suxwigb
Step 2: Determine which traces, if any, need to be deleted from each shot. Shots were deleted on the basis of excess noise.
Step 3: Delete bad traces using SUKILL. If a shot did not contain a trace to be deleted the file was copied and renamed file_num.kill.su for consistency.
A.B.
Figure 1. (A) File 195.su unadulterated. Traces 11 and 12 appear noisy and need to deleted. (B) File 195.kill.su shows the file after the deletion of traces 11 and 12
Shots
Traces
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1001
x
1002
x
x
1003
1004
1005
1006
1007
x
1008
x
1009
x
x
1010
x
1011
x
1012
x
x
1013
x
1014
x
1015
x
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
x
1031
x
x
1032
x
x
1033
x
1034
x
1035
x
x
1036
x
1037
x
1038
x
x
1039
x
x
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1040
x
x
1041
x
1042
x
1043
1044
1045
1046
x
1047
x
1048
x
1049
x
1050
x
1051
x
1052
x
1053
x
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
x
1069
x
1070
1071
1072
1073
1074
1075
x
x
1076
x
x
1077
x
x
1078
x
x
1079
x
x
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1080
x
x
1081
x
x
1082
x
x
1083
x
x
1084
x
x
1085
x
x
1086
x
x
1087
x
x
1088
x
x
1089
x
x
1090
x
x
1091
x
x
1092
x
x
1093
x
x
1094
x
x
1095
x
x
1096
x
x
1097
x
x
1098
x
x
x
x
x
x
x
x
x
x
x
x
1099
x
x
x
x
x
x
x
x
x
x
x
x
1100
Table 1. Xs represent the traces that have been deleted from each shot.
2. Reverse traces 13 24
The geophones that recorded traces 13 -24 in each shot experienced a mechanical malfunction that resulted in reversed polarity. In order to fix this problem each file was broken down into 2 contemporary files. The first contemporary file contained the traces recorded from the geophones that were working correctly, geophones 1-12, and the second temporary file contained the traces recorded from the malfunctioning geophones, geophones 13-24. Traces 13-24 were multiplied by negative one (suop) in order to restore them to the correct polarity. The two temporary files were then concatenated and renamed file_num.rev.su.
A.B.
Figure 2. (A) The abrupt shift in polarity can be seen at trace 13. (B) Image of file 1020 after correct polarity has been restored.
Rev_pol.sh
# set up working directories
SU_DIR='/home/willt/LSU1_1999_TJHughes/seismics/data/1999/Z/final'
first='1001'
last='1100'
first_trace=12
last_trace=24
for ((input_file =$first; input_file$SU_DIR/$input_file.rev.su
done
3. Filter the data
Step 1. A band pass filter can be applied to the data to cancel the negative effects of noise on the data. To determine the dominant frequency range of the data a fast Fourier transform was ran to decompose the amplitudes into frequency components. From the fast Fourier transform it was determined that everything with a frequency less than approximately 80 Hz is noise.
Figure 3. Result from a fast Fourier transform run on file 1001.g.su.
Sufft.sh - script
# DATA DIRECTORY
SU_DIR='/home/willt/LSU1_1999_TJHughes/seismics/data/1999/Z/su'
# fourier analysis fo data
file_name='1001.g.su'
sufft
