Refract is software to analyze first arrivals observed in a (wide-angle) seismic refraction profile.
Refract uses four different windows: the Model Window, the Plot Window, the Data Window, and the Section Window. Many of these windows share the same basic menu items. Some aspects of Refract are set in the Preferences Window.
A typical use of Refract is to try to find a seismic velocity structure that will reproduce observed arrival times. It can also be used to predict arrival times for suspected structures prior to acquiring data.
Users usually start in the Model Window, specifying the geometry of the refraction sensors and shots and the number of layers in the model. Opening the Plot Window will show the predicted arrival times for the starting model. Picks made from a refraction line can be entered by opening the Data Window. These data can be inverted by returning to the Plot Window and moving lines to fit the data; these line fits can then be inverted for a velocity structure from the Model Window. The lines will be updated to be consistent with the newly inverted model as not all sets of line fits perfectly match a velocity structure. The structure can also be edited in the Model Window to try and fit the data. An advanced trick is to make the plot with a reduction velocity; this makes it easier to see breaks between layers with similar velocities. A cross section of the model can be seen in the Section Window, where the depths of various interfaces can be seen interactively in an information pane.