disco_tutorial

DISCO - a database for seismic analysis

Tutorial for Disco

Program Disco is designed to organize seismic data in flat file databases which can be accessed and modified via a Graphical User Interface programed with Tcl/TK ("Tickle"). Data bases are set up in advance using a program called UW_2_DB.prl, a perl script that converts UW files to flat ASCII files readable by Disco.

Program Set up and Initiation

The suite of available seismic analysis and database programs are started by typing "disco" at the UNIX prompt. Before starting Disco several environmental variables should be set. These can be put into the users .cshrc or .tcshrc and set when logging into a shell: 
 
setenv DISCO_PATH ~/DISCO/Distribution
setenv progpath  $DISCO_PATH/NewDB
setenv binpath  $DISCO_PATH/bin
setenv dbpath $DISCO_PATH/NewDB
setenv DUMPING_GROUND /home/.scratch
setenv cpanel_size 650x270+200+0
(This is an example and should be set according the local array structure)

Main Window

The Main window contains the available database subsets. The user then highlights one or more of these database files and selects "open" from the main menu bar under "File".

For each database selected, a new window will open which includes the source paramteters from the flat ASCII-TEXT files in the database directory.

Once a database is open, the user can select events with the left mouse button and de-select with the right mouse button.

Merging Databases

Selected databases can be merged using the following steps: select the databases using the left mouse button; click the "merge" mouse button. A dialog box will be opened where the new (i.e., "merged") database's name can be entered. Additional databases can be opened from inside a database using the "Open" option. Click on "Open" from the file menu and a dialog box will show. Enter "datlib/fname" in the dialog box, where "fname" is the name of the database, typically having names ending in ".dat".

Data Window

Each event is represented by a "record" which is a horizontal line in the window. Records can be selected by clicking on the boxes and dragging the mouse.

Once records are selected, The user can "do" things to the events that are hi-lighted.

The data window allows one to organize the data by sorting and selection. Once events are selected, various analysis packages can be invoked which will apply to the selected events. These include, by default, 

xped
Geotouch
focal
cat pick
sortsta
modsta
file list
These programs are additional software installed as part of the DISCO distribution.

Xped

Xped is a pick-editor written in the X-window graphics language. It was developed at the University of Washington for analysis of event data from networks and modified extensively at Yale University by Jonathan Lees.

An event is display showing all the traces. These can be selected and manipulated by menu driven commands. Clicking on a trace provides a zoom window that provides an excellent way to make precise picks of the data including estimates of error bars. The information is stored in a "pickfile" which can be used for earthquake location, tomographic inversion, etc.

Geotouch

Is a three dimensional GIS program. There is extensive documentation on this program provided in

  • Geotouch: Three-dimensional GIS for Geology and Geophysics.

  • Geotouch: Documentation:
  • Geotouch: Published Paper in Computers and geosciences

    Focal

    This menu item starts a sequence of programs that plot the focal mechanisms of the events selected. The focal mechanism cards must already be in the files for this to work properly.

    Cat Pick

    This simply dumps out the files that contain the picks to standard output. It is useful for determining what information is stored in the database for each event.

    Sortsta

    This will produce a station sort of the data selected. This is very useful for examining multiplet events that occur in clusters in micro-earthquake regions.

    Modsta

    Similar to Sortsta, this will reexamine events that were selected by Sortsta and provide a way to modify picks from a station sort vantage. Good for interactive cross correlation of traces.

    Filelist

    Produces a list of the selected events to standard output.

    Jonathan Lees
    Last modified: Thu May 4 11:55:23 EDT 2000