Refraction Seismic Observations Over Layered Structures

This Java script will produce travel times over layered Earth structures. If there is nothing between the two horizontal lines shown below, you have a browser that does not support Java. In this case, you need to upgrade your Web browser to one that supports Java (or check that Java is turned on, in the preferences panel).

You can use this script to design a seismic survey for the project described in the Request for Bid. The model and survey specifications are controlled via the frame that should have appeared on your screen. This screen displays a schematic cross section of the Earth structure over which the seismic travel times will be calculated. Near the top of the plot is shown the location of the source, red circle, and the geophone spread. Layer depths can be varied by clicking and dragging each layer boundary near the middle of the plot. If you click and drag each layer near the right edge of the plot, you can vary the dip of each layer. Seismic wave speed within each layer is controlled by the slider bars shown below the plot.

The position of the source can be varied by clicking and dragging the source along the top line representing the Earth's surface. The position of the seismic spread can also be changed by clicking and dragging the spread. All other variables concerning data acquisition geometry (number of geophones in spread, geophone spacing, number of sources to stack, etc.) are controlled with slider bars shown below the cross section.

As you vary the acquisition geometry or the Earth structure, the travel times recorded by the array of geophones are displayed on the plot shown in your browser. Notice that the observations are color-coded by whether they represent direct or refracted arrivals.