Bosphorus Bridge connects Asia and Europe

The Bosphorus Bridge is thirty years old

Bosphorus NASA
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The connection to Europe reached Turkey thirty years ago with the construction of the first Bosphorus Bridge. It was basically the other way round for the city of Istanbul. For with the opening of the bridge in 1973, the city center on the European side was connected with the Asian motherland. In the city this triggered a boom. The cultural spaces have been in Istanbul since ancient times. The construction of the first Bosphorus Bridge also bridged the geological separation of the two continents. The Bosphorus, now with two bridges, is also located in a tectonically active area.

Computer generated graphic of a black hole. Black is the event horizon represented, surrounded by a circular disk of matter of gas. © NASA

Bridge to urbanization

The first Bosphorus Bridge in 1973 joined the historic city center in the European part with the affluent neighborhoods on the Asian side. In the western part were located next to the old town also industrial areas and working-class neighborhoods. Those who could afford it lived in the former suburbs of the eastern part, on the shores of the Bosporus and the Marmara Sea. The commissioning of the bridge gave the city an enormous boost in development.

As the distances within the city were significantly shortened in time, the urbanization wave, which had begun in the western part of the city since the 1950s, could continue into the eastern part. Industrial companies moved to the other side of the Bosporus and with them low-income population groups. New industrial and residential areas emerged, the suburbs shifted. The city expanded in a circular shape and showed in the late 1970s and early 1980s their current appearance of a modern metropolis. The boom soon required the construction of another bridge. In 1988, the second bridge over the Bosphorus was completed with the Fatih Sultan Mehmet Bridge.

View into the tunnel of the LHC with the accelerator ring. The blue-silver units contain the dipole magnets and the helium cooling system CERN

Bridges in tectonic marginal position

The Bosphorus also separates Europe from Asia tectonically. Istanbul lies on the edge of a break zone. Along this north Anatolian and Eastern Anatolian spur in the southeast of the country, the Anatolian plate is pressed westward like a plumed pea core (see figure). But are Istanbul and the Bosphorus bridges therefore seriously vulnerable to earthquakes?

In fact, geoscientists from the GeoForschungsZentrum Potsdam, together with their Turkish counterparts, have found increased tensions in the west under the Marmara Sea and east near D zce along the North Anatolian Fracture Zone (see figure). The increased voltage will eventually degrade in earthquakes. The last major earthquake occurred on May 1, 2003 in the east of the fault zone, ten kilometers north of the city of Bing l. Even if Istanbul is currently in areas of lowered tension, there is still the danger of an earthquake south of the city. However, since the time of an earthquake can not be determined, CEDIM is developing preventive measures in Karlsruhe. For example, the construction of structures should be better adapted to the seismic risk in order to minimize earthquake damage. display

The Bosphorus bridges are traffic and life nerve of Istanbul. They gave impulses for urban development and are an indispensable part of city life. Both suspension bridges capture earthquake vibrations with their softer construction. How strong these are, the Istanbul Kandilli Observatory monitors by means of sensors on the bridges.

Further links:

GeoPoint (Series of the Institute

for Geography of the University of Augsburg)

German Task Force Earthquakes at GFZ Potsdam

Kandilli Observatory and Earthquake Research Institute of Bosporus University, Istanbul (Turkish / English)

CEDIM - Center for Disaster Management and Risk Reduction

(GeoUnion, 19.09.2003 - Dr. Nicole Schmidt / GFZ Potsdam)