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specific order to the deformation points. The geometry file 
consists 3,163 lines in case of 0.5x0.5 degree size grid area for 
the study area so that a program was written to create this 
geometry data file automatically. In order to inverse GPS data 
with seismic constraint (seismic style and direction) to obtain 
strain rates and velocity field, two files, one from seismic 
inversion and the other from GPS inversion, needed to be 
combined. In order to be able to do that, a Java program was 
written. Strain programs give output files as ASCII files, as 
well. For instance, in order to draw velocity error ellipses, the 
diagonal values in the variance-covariance matrices from strain 
programs must be used (following some mathematical 
calculation). The first and second values in the diagonal of the 
matrices are the standard errors of east and north velocities, and 
the third one is correlation coefficient. And this has to be done 
for each of inversions. A sample of variance-covariance 
matrices obtained from strain programs is as follows: 
no. 1 LAT.= 30.00000 LONG.= 20.00000 
0.65244146E-01 -0.35264134E-01 0.24350502E+00 
-0.35264134E-01 0.65459771E-01 -0.37096604E+00 
0.24350502E+00 -0.37096604E+00 0.28188015E+01 
For analyzing output files as a whole and getting the strain and 
velocity results, visualization of these files are absolutely 
needed. In order to do this, GMT program was used. 
Nevertheless, GMT requires input files in a specific form (for 
strain crosses, input file columns must include respectively 
long, lat, epsl, eps2, azimuth of eps2 values - for velocity 
arrows and ellipses, columns must include long, lat, castward 
velocity, northward velocity, uncertainty of eastward velocity, 
uncertainty of northward velocity, correlation between eastward 
and northward components, station name) to visualize ASCII 
outputs. Therefore a program was written for converting matrix 
form data to one line form. As it can be seen here, the creation 
of IO files is pretty much complex. There are over 30 programs 
to be able to use this method and to see the results obtained. In 
order to shorten the time for obtaining results and speeding up 
the scientific discovery, all of these programs are wrapped as 
Web services. Thus, it prevents redundancy of development 
efforts. 
3. USER INTERFACE 
Easiness is targeted in the design of the user interface. The user 
interface was developed using ASP.NET as shown in Figure 3. 
ASP.NET is used to create Web pages and Web services. 
ASP.NET provides developers casy programming environment 
and makes exposing and calling XML Web Services simple. 
The interface has many functions including a brief information 
part about the system, frequently asked questions section where 
the users of the system can find descriptions of terms and 
additional information, a newsletter section which is a periodic 
publication of system related news, a messaging part for 
communication among users, and a contact information page for 
the user feedback and inquiries. Archive section is for users’ 
application history storage and search. 
   
  
Figure 3. Web interface 
Users are able to select a region by latitude/longitude boxes and 
specify the grid size, then compute strain rates using inversion 
Web services. The methods created in this web services can be 
used by any application on the Internet. After entering the 
parameters, each request is given a unique id number according 
to the time the request arrived at the web server. Then input 
files are created and stored in the workspace. The application 
runs the programs and output files are created. GMT is executed 
for each line in those files including strain and velocity 
information. GFW (world files for gif images) files are created 
for georeferencing strain and velocity images in ArcIMS 
environment. Batch files which run GMT creates PS files. Then 
ImageMagick [11] program converts PS (postscript) files to GIF 
(Graphics Interchange Format) files. ImageMagick is free 
software to create, edit, and compose bitmap images from the 
command line. In order to create a service in ArcIMS, a map 
configuration file (with axl extension) must be created first. The 
map configuration file is a text file that stores information about 
map design. This file is written in ArcXML, which is an XML 
used specifically for creating Web-based products. ArcIMS 
Author is for creating AXL file, the Administrator creates and 
starts ArcIMS Services, and the Designer is for creating the 
look of the web site. In the application for each request, 
ArcIMS's ArcXML file is created and GIF images are 
embedded into ArcXML file as a layer (Figure 4). 
ESRI.ArcIMS.Server.dll is to provide a connection between the 
client and ArcIMS Application Server. 
  
  
  
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Figure 4. Output map showing strain crosses 
237