You will need to have the Java runtime environment (JRE) installed on your computer in order to use this software. As of Java Version 7 Update 51, you will also need to add https://www.crewes.org to the Java Exception Site List. This has been tested in Windows 10 using Microsoft Internet Explorer, Microsoft Edge and Mozilla Firefox.
To start the Hodogram Explorer click on the 'Launch' button above.
To use this Explorer you should first have four columns of ASCII data from a receiver. These should consist of three traces from, say, a 3-C geophone (for the same shot and receiver) and an accompanying time trace. The four columns may be in the same file or in separate files. Below is an example of an ASCII file with six columns. The relevant columns have been circled, with time in the fourth column and the vertical trace in the sixth column. The two horizontal traces are in other files not shown.
One easy way to copy-and-paste the data into the Explorer is to type Ctrl-a ("select all") in the ASCII file and then Ctrl-c ("copy"). The ASCII data will be scrolled to the end of the file and appear highlighted after the Ctrl-a action:
The Explorer program, when first opened, will appear like this:
Click inside the text area, then type Ctrl-a to select all the contents. The relevant part of the control panel will then appear like this:
Then type Ctrl-v ("paste") to transfer the copied data. The result looks like this:
Next check off the "Time" and "Vertical" boxes, as these indicate the data you are reading from this file:
Next change the column numbers to "4" and "6":
Right now there is a field a couple of lines down that reads "Data read in: none". After you click the "Read data" button, this changes to show the number of elements read in from each column.
Note that checkboxes have disappeared for "time" and "Vertical". It is no longer possible to read in data for these quantities unless you restart the Explorer. Two other checkboxes remain though. You should now repeat the steps above for other files to obtain the horizontal shear traces. The Explorer might then read as follows:
Finally click "Plot Hodograms". The left-hand side of the Explorer will appear as below:
Note the following:
- the tall, narrow plots display the three time traces, all with the same scaling
- the square plots diplay the hodogram crossplots for all three component pairs
- best-fit lines for the data are shown by a straight red line in each hodogram
- best-fit polarization angles are given in degrees at the top of each hodogram
- you may change the time limits of the plot using the vertical slider bars
- you may change the color scheme of the plot using the drop-down menu at the bottom of the control panel
Created by Chuck Ursenbach. First created May 18, 2007.
Technical NotesA hodogram displays a two-dimensional projection of a trajectory of a point moving in space. It is a crossplot of any two components of motion of the object. It is used in exploration seismology to find information on the direction travelled by a wave before it is detected at a receiver. The motion of the receiver itself is being plotted in the hodogram.
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