GROUND DEFORMATION MAPPING USING INSAR 
C. Aydöner **, D.Maktav®, E. Alparslan“® 
* TUBITAK-MRC, Earth And Marine Sciences Research Institute, 41470 Gebze Kocaeli, Turkey - 
(Cihangir.Aydôner/Erhan.Alparslan)@mam.gov.tr 
° ITU, Civil Engineering Faculty, 80626 Maslak Istanbul, Turkey - dmaktav@itu.edu.tr 
KEY WORDS: InSAR, Ground Deformation, Earthquake 
ABSTRACT: 
SAR interferometric data can be used for extracting three dimensional information of the earth’s surface by using the phase part of 
the radar signal. In this study, available SAR interferometric data acquired before and after the Marmara earthquake of 1999 and 
provided by ESA were used for mapping the ground deformation in the satellite line of sight (LOS) in the Izmit province. The 
interferometric suitability of the available SAR data was tested by computing the base length. In order to construct the 
interferogram, ERS-2 satellite data having the orbit numbers of 22556 and 23057 were processed using ROI-PAC software, the 
InSAR software package developed at the Jet Propulsion Laboratory, California, USA. Instead of phase unwrapping technique, all 
fringes were digitized manually from the interferogram to compute relative LOS ground deformations. Thanks to continuous DGPS 
stations located both at the Northern and Southern parts of the NAF (North Anatolian Fault), absolute LOS ground deformations 
were mapped. The DGPS stations used for computing absolute ground deformation are still operated by TUBITAK-Marmara 
Research Center (MRC), Earth and Marine Sciences Research Institute (EMSRI). 
1. INTRODUCTION 
SAR Interferometry was first used for topographic mapping by 
Graham in 1974 (Graham, L.C., 1974). The first practical 
results were obtained by Zebker and Goldstein using side 
looking airborne radar in 1986 (Zebker, H.A., Goldstein, R.M., 
1986). Studies on interferometric SAR (InSAR) were extended 
after the launch of ERS-1 and ERS-2 satellites, which can 
provide interferomeric data acquired only one day apart. The 
number of scientific research on InSAR technology has also 
exploded since the launch of new satellites such as ENVISAT. 
In order to obtain SAR Interferometric data, two spatially 
separated antennas the physical separation of which is called 
the interferometric baseline are mounted on a single platform or 
one antenna is mounted on a satellite and data sets are acquired 
by passing the same area twice. In the latter case, the 
interferometric baseline is formed by relating radar signals on 
repeat passes over the target area. This approach is called 
repeat-pass interferometry. 
There are various publications on estimating earthquake 
parameters using INSAR measurements in Izmit region 
[Reilinger et al., 2000], [Feigl et al., 2002], [Wright et al, 
2001], [Wright et al., 2001] [Delouis et al., 2002]. 
In this study, available SAR interferometric data, which were 
acquired before and after the Marmara earthquake of 1999 and 
provided by ESA were used for mapping the ground 
deformation in the direction of satellite line of sight (LOS) in 
the Ízmit province. The interferometric suitability of the 
available SAR data was tested by computing the base length. In 
order to construct the interferogram ERS-2 satellite data having 
the orbit numbers of 22556 and 23057 were processed using 
ROI-PAC InSAR software package developed at the Jet 
Propulsion Laboratory. In place of phase unwrapping technique 
  
all fringes were digitized manually from the interferogram to 
compute relative LOS ground deformation. Thanks to 
continuous DGPS stations located both at the Northern and 
Southern parts of the NAF (North Anatolian Fault), absolute 
LOS ground deformation was mapped. TUBITAK-MRC, Earth 
and Marine Sciences Research Institute currently operates the 
DGPS stations used for computation of absolute ground 
deformation. In the framework of the study, the absolute LOS 
deformation occurred near the NAF could not be estimated 
because the ground deformation amount was greater than the 
wavelength of ERS-2 satellite sensor. 
2. DATA USED 
Information on SAR satellite data used in this study is given in 
Table 1. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
No SAT Orbit Track Date 
1 ERS-1 42637 064 10-09-1999 08:45 
2 ERS-2 20459 064 20-03-1999 08:45 
3 ERS-2 20960 064 24-04-1999 08:45 
4 ERS-2 22964 064 11-09.1999 08:45 
5 ERS-2 20230 336 04-03-1999 08:48 
6 ERS-1 20364 336 07-06-1999 08:48 
7 ERS-1 42408 336 25-08-1999 08:48 
8 ERS-2 00691 336 08-06-1999 08:49 
9 ERS-2 22735 336 26-08-1999 08:48 
10 ERS-2 18226 336 15-10-1998 08:48 
11 ERS-2 19228 336 24-12-1998 08:48 
12 ERS-1 42730 157 16-09-1999 20:14 
13 ERS-2 22556 157 13-08-1999 20:14 
14 ERS-1 42229 157 12-08-1999 20:14 
15 ERS-2 23057 ]57 17-09-1999 20:14 
  
  
  
  
  
  
Table-1. Information on SAR satellite data used in this study 
* TUBITAK-MRC, Earth And Marine Sciences Research Institute, 41470 Gebze Kocaeli, Turkey 
  
    
   
   
    
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
    
      
     
   
   
   
   
   
   
   
    
   
     
   
   
    
   
   
  
  
  
    
   
  
Interna 
3.1 Se 
Interfe 
Base | 
approp 
and an 
also be 
(Bı) aı 
exist a 
¥ 
Figure 
Base le 
selectic 
base le 
(Gens, 
numbei 
suitabk 
we onl 
32 .D 
After s 
used to 
the phe 
Since 
deforn 
total o 
to the 
calcul: 
A num 
inform: 
using tl