The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
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over other, cause shift, and tilt stress in the geological structures. 
The North-Anatolian Fault is one of the biggest and most active 
tectonically line in the Near East. Big shift and tilt movements 
combined with an enormous pressure lead to high stress energy 
in the plates. Beside small movements which usually does not 
harm, big releases of the plates stress lead to strong and dan 
gerous earthquakes. The entire NW part of Turkey is highly for 
geological shocks. Monitoring the history of such shocks along 
this fault show that the epicentres of the earthquakes moved 
during the last decades from east to west towards the sea of 
Marmara. 
Figure 2: An image from Enric Marti of the Associated Press 
that was taken for the New York Times on August. “A mosque 
stood with a few other structures amid the rubble of collapsed 
buildings in the town of Golcuk 60 miles east of Istanbul”. 
[http://arrowsmith510.asu.edu/Ex-ercises/Exercise3/] 
The last strong shock hit Turkey on August 17 in 1999 and 
caused a dramatic disaster. Measured at 7.4 on the Richter Scale 
at the U.S. Geological Service in Golden, Colorado, the temblor 
was centred between Izmit and Bursa, about 80 km east of Is 
tanbul. This was the most powerful earthquake ever to hit Tur 
key. More than 15,000 people died, 23,000 became injured, and 
500,000 finally were homeless. Izmit is situated on the North- 
Anatolian Fault in the Izmit Bay. This fault leads through the 
Sea of Marmara just 50 km south of Istanbul’s centre and arcs 
to the southwest towards the Aegean Sea, also well known for a 
high potential for earthquakes. 
Analyzing the Izmit Earthquake, we have to separate the differ 
ent mechanisms that created the damages. Main shockwaves 
can shake buildings and destroy them especially such that have 
been built up illegal ignoring rules for save constructing. Many 
buildings have been damaged or destroyed by secondary waves, 
the so-called S-waves. These waves came a few seconds after 
the primary ones and are usually stronger against buildings. 
Landslides on the hilly terrain where complete buildings slid 
down including their foundation have destroyed other houses. 
The combination of heavy load on the soil, big slope, undercut 
basis of the hills e.g. by roads and sometimes liquid in the 
sediments, can lead to a collapse like failure of the sediments 
and rocks. A similar effect is the liquifiction of ground that even 
can happen in flat terrain. The saturated soil starts to collapse 
during shaking and the foundation of buildings sack in or break. 
Clayish and silty material support such effects especially in 
combination with high water content. 
A Tsunami flew after the Earthquake into the Izmit bay. With a 
maximum run-up of 2.5 m along the northern coast of the bay 
and 1 to 2 m on the southern coast, this Tsunami was a rela 
tively small one and mainly flooded the area. However, the Sea 
of Marmara bids a high potential for creating small and medium 
sized Tsunamis, which can be even much higher and stronger 
than the one detected here. 
Beside these primary effects of a earthquake, secondary disas 
ters usually aggravate the situation. Broken pipelines, espe 
cially gas-lines, cause fires that easily can spread in a partly de 
stroyed city. Industry can create big environmental disasters as 
seen after the shock by burning oil tanks and running out of pet 
rol. The possibilities of rescue teams are very limited since 
the access to these areas is difficult. Besides that, criminal ac 
tivities might start e.g steeling goods from shops. Sometimes 
the secondary effects are more destructive than the primary 
ones. 
Istanbul is close to this fault and during the Izmit Earthquake, 
in Istanbul many buildings have been destroyed and 3000 peo 
ple killed, mainly in the southern part of the Mega city and 
mainly in so called Gececondo - districts. As mentioned in 
chapter 1.2, the high dense of urban structure increase the risk- 
level for the citizens being harmed by geological shocks. 
Within the last 50 years, Istanbul has grown to a Mega city with 
more than 16 Mio inhabitants. Rough terrain, forests and the 
black sea limit the sprawl to the north, so Istanbul expanded to 
the south on both sides along the coastline of Marmara Sea. The 
strongest expansion vector leads to southeast and already has 
met the Izmit bay. 
Figure 3. The Earthquake-Map for Istanbul highlights areas 
where strong shocks have to be expected: the southern part is 
the most endangered one. [http://www.akut.org.tr]