GeoMapApp© Help
Single Channel Reflection Profiles
This database consists of single channel seismic reflection profiles, originally recorded in analog form, which have been converted to digital files. They display the sediment layering below the seafloor.
When the window appears, the Main Map Window at the upper left displays tracklines of ships that recorded single channel seismic reflection profiles. Clicking on a line selects a track and the name of the data file appears along with date and time of first recording.
Clicking on the View Profile button or double-clicking the track name loads the seismic data into the lower window pane.
You may also press Load Previously Digitized Products if you have tracings of reflectors that you have made and saved in previous sessions.
The reflection profiles appear in the bottom window pane. The vertical scale is in seconds of two-way travel time. One second is equivalent to 750 meters in the water column. As you move your cursor in the seismic profile window, the display shows name of the cruise, longitude and latitude, depth (meters ), and crustal age in millions of years (Ma) for the data point along the ship's track. Note the highlighted portion of the ship's track in the Main Map Window.
Also displayed, based on the vertical position of your cursor, is depth (z) in meters from the sea surface to your cursor, two-way traveltime (tt) in seconds from the sea surface to your cursor, the sediment thickness in meters from the seafloor to your cursor position, and the back track depth (btz) in meters of the formation of the oceanic crust at your cursor location. Depth in the seismic profile is calculated for a constant sound velocity of 1500 m/s. Crustal age is interpolated from the global compilation of Muller et al. (1997).
The red line is the sea bottom that has been digitized from separate echo-sounding data. It is used to help register the reflection profile. The red line can be toggled on and off with the show bottom 
icon.
The reflection profile can be scrolled. The red portion of the track in the Main Map Window indicates the location of the portion of the reflection profile visible in the lower window pane.
The bottom left window pane has a toolbar with seven icons 
Zoom in - click on this tool button to enlarge the profile view.
Zoom out - click on this tool button to shrink the profile view..
Digitize - click on this tool to digitize horizons in the profile. When you finish digitizing a horizon press 'enter' . Click on this tool again to begin to digitize a new horizon.
Add text - click on this tool to add a text label to your text file of digitized horizons.
Select - if you have digitized several horizons, you may use this tool to select the digitized horizon you wish to display on your profile.
Seafloor - toggle the red line (seafloor bathymetry) on and off.
Save - when you are done, click on this button to save a text file of longitude, latitude and two-way-travel-time of your digitized horizons.
Here is an example showing two digitized horizons and a text label.
Don't forget to press Close when you are done, to close the single channel reflection interface and release memory.