.de BR
.in 0
.in +8n
.ti -3n
..

.Th REFRACTION
.S2 SUMMARY:
Enter Refraction Processing Mode for Record Section

REFRaction [ON|OFF] [Ex|Reg|Tel]

.S2 INPUT:

.S2 DESCRIPTION:
This places the PLOTRECORDSECTION (prs) display into an interactive mode for refraction studies.
.sp
Ultimately we will have data structure for the arrivals, and when
gsac terminates these will be written to an ASCII file. Also if REFRACTION
is even invoked, then the picked refraction lines will be displayed on the screen using an XOR pen - this is useful if one leaves PRS -- or if reread then get rid of everything - think about all of this, perhaps we need a save button
instead of a data structure
.BR
Ex - Exploration mode - Filter frequencies are 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 500, 1000 Hz
.BR
Reg - Regional mode - Filter frequencies are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100 Hz
.BR
Tel - Teleseism mode - Filter frequencies are 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.2, 0.25, 0.5, 1 Hz
.BR
.S2 EXAMPLES:
The terminal text output of the DoRefr command is the following if the value is accepted:
.nf
 S: Refr t0 -0.005536 p 6.474635 (sec/km) Vel 0.154449 (km/sec) Refractor 1
 S: Refr t0 0.159714 p 0.513774 (sec/km) Vel 1.946381 (km/sec) Refractor 2
.fi
.sp
which indicates that these are S-wave refraction measurements for the first two refraction arrivals. This information can be used in a simple program to compute layer thicknesses.
.sp
The terminal text output of the DoRefl command is the following if the value is accepted:
.nf
S: Refl t0 0.154164 p 6.384913 (sec/km) Vrms 0.156619 (km/sec) Reflector 1 Multiple 1
S: Refl t0 0.308500 p 5.856309 (sec/km) Vrms 0.170756 (km/sec) Reflector 1 Multiple 2
.fi 
These values can be used to determine layer thicknesses.
.sp
For each PRS001.PLT or REFR001.PLT file there is a corresponding PRS001.CTL or
REFR001.CTL control file, which can be used to invoke the program refmod96 to make model predicted overlays.
.sp
In addition there is a refrpick.tmp file which will ultimately be
used by an inversion program.
.S2 NOTE:
On July 10, 2010 the interactive cursor will respond to the ~ (tilde) character by creating a screen dump with name DUMPxxx.PLT. This dump includes the menu and is introduced to assist documentation.



.S2 "SEE ALSO":
