Next: Frequency filtering Up: 2-D Seismic Data Processing Previous: Generating this document

Reading data

In this part of the tutorial, you will experiment with reading a seismic dataset in SU format, converting it to RSF format, examining its values, and displaying it on the screen. You are asked to answer a series of simple questions. Insert your answers by editing the nankai/paper.tex file.

Change directory to nankai/data.
Run
```
scons -c
```
to remove (clean) previously generated files.
Run
```
scons shots.rsf
```
This command will find the SU file for the Nankai data and convert to two files: trace header data (tshots.rsf) and trace data (shots.rsf).
Examine the trace data file shots.rsf by running
```
more shots.rsf
```
What is the data format used in this file? How many traces does this file have (n2= parameter)? How many time samples per trace (n1= parameter)?
$\fbox{\parbox{\boxwidth}{\textbf{Answer:} }}$
Note that a more convenient way to check parameters is running a Madagascar program sfin:
```
sfin shots.rsf
```
Examine the range of values in the trace data file by running
```
sfattr < shots.rsf
```
What is the maximum value? How many zero samples are in this file?
$\fbox{\parbox{\boxwidth}{\textbf{Answer:} }}$
Run
```
scons shots2.view
```
to display all shot gathers in the Nankai dataset. Some traces are missing. To view the mask of the missing traces shots, run
```
scons smask.view
```
and observe where missing traces are located.
Examine the content of the trace header file tshots.rsf by running
```
sfheaderattr < tshots.rsf
```
To get a short description of different keys, you can also run
```
sfheaderattr < tshots.rsf desc=y
```
Run
```
scons shot.view
```
to window and display traces corresponding to the 1707th shot record (Figure 1).
Run
```
scons offset.rsf
```
to window values of offset (receiver-shot distance) for the 1707th shot record. Examine the values by running
```
sfdisfil < offset.rsf
```
What is the offset for the receiver closest to the source? What is the distance between receivers?
$\fbox{\parbox{\boxwidth}{\textbf{Answer:} }}$

shot
Figure 1. Wiggle plot of the 1707th shot record from the Nankai data.
Open the SConstruct file in your favorite editor and find the command which windowed the 1707th shot record. Change it to window different shot records. Run
```
scons shot.view
```
again to see the effect of the change. Edit the plot title to reflect the change.


shot Figure 1. Wiggle plot of the 1707th shot record from the Nankai data.

Next: Frequency filtering Up: 2-D Seismic Data Processing Previous: Generating this document

2016-06-07