Simple model of faults in Utah, showing effect of hypothetical earthquake on Wasatch fault on nearby faults. (Made with the help of Walt Arabasz and Wu-Lung Chang.) Shows use of lnconvert, lnprj, lnsegment, segs2dlc, elfpatch, xss.
Note that answers given in [square braces] are defaults which will be used if no answer is supplied (just hit the carriage return).
Model was constructed from a fault line-file for Utah in QP format. The necessary steps involve running lnconvert to change to .LIN line format, running lnprj to project the lines, and lnsegment to simplify the fault lines into 10km long segments. (Faults shorter than 5km in length are dropped in this last step. The last segment in a long fault may be shorter that 10km - but longer than 5km, if retained.) Finally segs2dlc changes the segments into vertical rectangular dislocations.
> lnconvert
Infile: [.lin] ugs.qfaults.master
Give line type (.OLN/.BOLN/.BLN/.LIN/.GEN/.QP/.OPP/.PF/.AXYZ/.XYZ/.BLXYZ/QUIT): [.LIN] .QP
Outfile: [ugs.lin] utah_faults.lin
Report on progress? (y/n): [n]
Project or unproject lines? (y/n): [n]
Winnow points on line by distance? (y/n): [n]
Segment line into constant-length pieces? (y/n): [n]
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
** Line has less than 2 points...nothing will be written.
NUMBER OF LINES READ = 2308
NUMBER OF LINES SAVED = 2256
NUMBER OF LINES WITH LT 2 POINTS = 52
STOP:
> lnprj
Infile: [utah_faults.lin]
Outfile: [utah_faults.lin] .lin_prj
Outfile: [utah_faults.lin_prj]
Give line type (.OLN/.BOLN/.BLN/.LIN/.GEN/.OPP/.PF/.AXYZ/.XYZ/.BLXYZ/QUIT): [.LIN] .lin
Report on progress? (y/n): [n]
Forward or inverse projection? (f/i): [f]
Projection number (99 for help): [0] 4
Give coordinates in decimal degrees or d:m or d:m:s
(e.g. -120.52 or -120:31.2 or -120:31:12)
Central meridian: -111.5
Base latitude: 37
New azimuth of North-direction: [0.]
Projected coordinates are in kilometers...
NUMBER OF LINES READ = 2256
NUMBER OF LINES SAVED = 2256
STOP:
> lnsegment
** Best to project line before segmenting...
Infile: [utah_faults.lin] utah_faults.lin_prj
Give line type (.OLN/.BOLN/.BLN/.LIN/.GEN/.QP/.OPP/.PF/.AXYZ/.XYZ/.BLXYZ/QUIT): [.LIN]
Outfile: [utah_faults.lin] utah_faults.lin_10km
Give line type (.OLN/.BOLN/.BLN/.LIN/.GEN/.QP/.OPP/.PF/.AXYZ/.XYZ/.BLXYZ/QUIT): [.LIN]
Report on progress? (y/n): [n]
** Lines shorter that half-segment-length will be lost
Segment length (usually km): [0.] 10
**Dist between pts less than 1.00000E-03 Skipping to next pt.
**Dist between pts less than 1.00000E-03 Skipping to next pt.
**Dist between pts less than 1.00000E-03 Skipping to next pt.
**Dist between pts less than 1.00000E-03 Skipping to next pt.
NUMBER OF LINES READ = 2256
NUMBER OF LINES SAVED = 428
STOP:
> segs2dlc
** Generates a model from segments in a linefile.
** Linefile should be projected and segmented.
Line file: [utah_faults.lin] utah_faults.lin_10km
Give line type (.OLN/.BOLN/.BLN/.LIN/.GEN/.QP/.OPP/.PF/.AXYZ/.XYZ/.BLXYZ/QUIT): [.LIN]
Name for model file:: [utah_faults.dlc]
Depth to top of dislocations: [0.]
Depth to bot of dislocations: [10.] 15
Height of one dislocation: [15.]
** Number stacked = 1
Approx length of one dislocation: [15.] 10
Want FRIC line also to run BVDS? (y/n): [y] n
Rake angle (0=LL; +/-180=RL; +90=Reverse; -90=Normal): [180.] -90
** Number of dislocations = 554
STOP
The resulting dislocation file was then attacked with a text editor to change all dips to 60 degrees to simulate normal faulting (global substitution on " 90.00 ". Clearly not all faults are normal, nor are they all vertical. In a refined model each fault would be assigned a dip and a rake appropriate to it known behavior.
In order to simulate an earthquake on the Wasatch front, we used xss (m - for mouse - option) to discover the names of 4 dislocations in an appropriate area for such an earthquake. Using the text editor, these dislocations were assigned 2 meters of dip slip. The resulting modified dislocation file is called utah.dlc.
> elfpatch
Parameter file: [utah.par]
Dislocation file: [utah.dlc]
Number of dislocations = 283
Displacement table? (None, Read, Write, Zero) (n/r/w/z): [n]
Patch stress (.pstr) outfile: [utah.pstr]
*** Getting slip boundary conditions...
Non-zero slip for dlc # 26
ss,ds,op = 0. 2.00000 0.
Non-zero slip for dlc # 27
ss,ds,op = 0. 2.00000 0.
Non-zero slip for dlc # 28
ss,ds,op = 0. 2.00000 0.
Non-zero slip for dlc # 29
ss,ds,op = 0. 2.00000 0.
Friction coefficient: [0.] .6
Cohesion: [0.]
Include pore effects? (y/n): [n]
If answer to next question is "n" then rakes will be used to calculate deltaCFF...
Add regional stresses? (y/n): [n]
STOP:
The resulting change in CFF can be viewed by viewing the results in the utah.pstr file using xss:
> xss
>Plot-only, Plot-and-Save, or Save-only? (P/p/Ps/ps/s): [p] >xss.ans
** Opening output file to save answers = xss.ans
>Plot-only, Plot-and-Save, or Save-only? (P/p/Ps/ps/s): [p]
Earthquake to view (lp/mh/other): [other]
Parameter file: [utah.par]
Dislocation file: [utah.bdlc]
Dislocation file: [utah.dlc]
Number of dislocations = 283
File with view parameters (or "none"): [utah.see]
** Projections reset in projset...
Add regional stresses? (y/n): [n]
Scale view heights by value? (y/n): [n]
Plot is about 10.00 inches wide and 10.00 inches high.
Data area is 10.00 inches wide and 10.00 inches high.
Scale = 1 : 3149606
Plot outlines around dislocations? (y/r/n): [y]
Color file (h for help): [/home/simpson/color/12rbplustek.clrs]
Number of colors read = 13
** added colors = white yellow magenta cyan blue green red black
Colors to use for scale: [12]
Display color scale? (y/n): [y]
Option (h=help): vf
pstr file: [utah.pstr]
** CFF is put into array value as well as into cff.
** number of .pstr lines read = 283
Option (h=help): vp
: min, max = -31.2980 9.23002
Give number of contours (0 for file): [11]
Possible contours:
MIN, INT, MAX = -24.0000 3.00000 6.00000
Give MIN level: [-24.] -.5
Give INTerval: [3.] .1
Old title: Delta_CFF (read from .pstr file)
New title [Give CR to use old; + to add to old; @ for blank]...
Title:
Option (h=help): li
Line file (h for help with abbrevs): [utah.oln] wstates
wstates = /usr/local/data/linedata/wstates.bln
Project lines? (y/n): [y]
Option (h=help): q
Hold plot on screen (seconds): [0]
STOP: