004 
  
ill 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
And the last measurements were also implemented in Avcılar. 
In these measurements, aerial photographs taken in four 
different scales and time were used. These photographs were 
taken in 1987 and in 1:18 000 scale, in 1993 and in 1:35 000 
scale, in 1998 and in 1:18 000 scale and after earthquake in 
1999 and in 1:16 000 scale (Figure 6). 
  
Figure 6. Aerial Photograph of Avcilar 
Applying measurements on the different scaled and dated aerial 
photographs, the aim was to explain the movements occurred 
not only with earthquake but also before earthquake too. 
Displacement vectors that obtained from Avcilar measurements 
were presented for the years 1993 - 1987, 1998 — 1987, 
1998 — 1993, 1999 — 1987, 1999 — 1993 and 1999 - 1998. The 
results of these vectors are shown in Table IV. 
  
  
AVCILAR AREA 
RESULTANT DE DN DL DV 
VECTORS (m) (m) (m) (m) 
  
  
Number of Points = 190 
  
  
Between 1993 and 1987 | -0.293 | 0.693 | 1.157 | 1.183 
  
  
Between 1998 and 1987 | 0.179 | 0.331 | 0.621 | -0.595 
  
  
Between 1998 and 1993 | 0.471 | -0.380 | 0.914 | -1.782 
  
  
Between 1999 and 1987 | -0.024 | 0.755 | 0.944 | -1.093 
  
  
Between 1999 and 1993 | 0.269 | 0.062 | 0.749 | -2.257 
  
  
Between 1999 and 1998 | -0 204 | 0.424 | 0.633 | -0.514 
  
  
  
  
  
  
  
  
Table 4. Avcilar measurements and results 
  
651 
These results show us that the movements have different 
characteristics in these measurements. The displacements 
between the years 1998 - 1993 have a reverse direction when 
they compared with the displacements between the years 
1993-1987. And of course the displacements between the years 
1999 and 1998 have also another characteristic because of the 
earthquake. But it is interesting that the displacements between 
the years 1993 and 1987 have same directions with the 
displacements occurred in the earthquake in horizontal 
coordinates (Figure 7 and 8). 
  
ot J 
Mao 
= TRE 
  
Figure 7. Displacement vectors for horizontal coordinates 
between the years 1999 and 1987 
  
  
rH 
  
| am 
ill i 
Li 
28 42 28 43. 28° 44 28 45' 
i 
[LH 
  
  
Figure 8. Displacement vectors for vertical coordinates between 
the years 1999 and 1987