International Archives of the Photogrammetry, Remote Sen 
  
’ Zeytinburnu 
DU 
- 
= Sea of Marmara 
  
Figure 3. Inundation map drawn for the coastal area in front of 
Zeytinburnu port. Line definitions are same as in Figure 2. The 
inundation distance was calculated on the basis of 
circumstantial characteristics of the inundation area along the 
coastal zone which was classified for smooth terrains and areas 
covered in buildings. 
Sea of Marmara 
Figure 4. Inundation map drawn for the Haydarpasa Port and 
Kadikóy inlet placed at the Bosphorus junction of the Sea of 
Marmara. Occasional steep coastal terrain at some localities 
limits inundation. These lines are subject to changes on the 
basis of prehistoric tsunami deposits found along the coast, 
further computer tsunami modelings, and scientific studies of 
other tsunamis that occurred in the Sea of Marmara. 
  
sing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
3.2 Precision and Accuracy of the Inundation Lines 
One of the largest sources of error is uncertainty in the absolute 
run-up elevation at the open coast. Therefore, it is assumed to 
be 2, 2.5 and 3 m in our calculations. 
The numerical grids were refined enough to simulate the details 
of the land topography (pixel size + 50 m). Therefore 
uncertainty in the inundation distance (horizontal accuracy) is 
small. 
Due to the inherent uncertainties in tsunami models, the 
parameters we used in calculations (models, topography etc) 
and our judgement to infer inundation, the resulting error is 
difficult to quantify. Vertical precision, for example, depended 
on the spacing of the elevation contours and the proximity of 
the contours to the inferred run-up elevation. The maximum 
uncertainty between contours is 100 percent of the contour 
interval. Where the inundation distance fell by chance at or very 
close to an elevation contour, the precision is better. In addition, 
the precision may be large at inlets, lagoons, river mouths and 
estuaries and smaller at steep shorelines. In all cases the 
precision of the inundation lines is limited by the resolution of 
the images to no better than +5 m horizontal and £1.2 m 
vertical. 
In normal conditions, sea level changes should be considered 
and possible co-seismic subsidence should be added to results 
of inundation limit as an additional run-up. Tides are small in 
amplitude; however maximum effective wave height in the 
region is as much as 3.3 m in winter. During persistent 
southerly winds, surges caused by wind setup are as high as | m 
along the northern coasts of the Marmara. On the other hand, 
co-seismic subsidence must be considered in some alluvial flats 
along the European coasts. Subsidence inferred from the 
prehistoric geologic record may increase in large estuaries. 
Such factors may make minor differences in the mapped 
inundation. 
4, CONCLUSION 
Tsunamis are unpredictable events and increasing the 
uncertainty of preventive action, contribute to a very low social 
memory on these phenomena that is inversely related with a 
high demand for decision criteria based on scientific 
knowledge. On the basis of this contextual situation. which 
shows us the urgent necessity to develop integrated actions 
research, tsunami risk maps in a microzonation sense along the 
Sea of Marmara coasts of Istanbul were produced. The absolute 
run-up elevation at the coast is assumed to be 2, 2.5 and 3 m in 
our calculations. For particular areas, the inland distance of 
inundation is apparently greater. Kücükcekmece lagoon is 
separated from the coast by barriers with present elevations on 
the order of a few metres. The inferred inundation is high 
enough, within the uncertainties of the run-up estimates, to 
inundate this lagoon. 
We have produced 3 different case scenarios for absolute run- 
up elevations of 2, 2.5 and 3 m at the coast. In fact, in normal 
conditions, a single line representing a worst case scenario was 
preferable, for it simplified the preparedness response of city 
officials and it better informed the general public (Synolakis et 
al, 2001). However, a comparison of low and high risk lines on 
a same map indicates most vulnerable localities and helps us to 
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