The 1999 Izmit Earthquake

A sudden movement of the earth's crust caused by the release of stress accumulated along geologic faults or by volcanic activity is known as an Earthquake (American Heritage dictionary). According to Richter magnitude scale, with magnitude 3 or lower earthquakes will be mostly imperceptible and magnitude 7 or more will cause serious damage over large portion of areas. A magnitude of 7.4 deadly earthquake struck the city of Izmit, Turkey,on August 17th, 1999 around 3 A.M in the morning when the city was in deep sleep and killled over 25,000 people and 300,000 people were left homeless.

RichterScale.gif It was one of the most devastating earthquake in Turkey. According to the United States Geological Survey, 1999 Izmit earthquake with magnitude of 7.4 occurred on world’s one of the longest strike slip (horizontal motion) faults: the east-west trending North Anatolian fault. Izmit, at the end of the Marmora Sea was the closest major city that was dreadfully affected by earthquake. Beside Izmit, this earthquake has affected Istanbul causing tremendous damages. According to the United State Geological Survey, the epic center of this earthquake was located near the Golcuk Town of western part of Turkey. It was determined to be at the latitude of 41.81̊ North and longitude of 30.08 ̊ East by Koeri with the depth of approximately 10 to 16 km. Moreover, the maximum ground motion that has been recorded varied between 0.3 and 0.4g with 37 seconds of duration.

Figure 1: Richter Scale presenting the magnitude with the scale of damages.

locationb.jpg The consequences of the 1999 Izmit earthquake were dreadful. Over 25, 000 people
were killed from this earthquake and approximately 300,000 people were homeless and injured due to the building collapsing. People were unable to take action due to this unexpected earthquake in the mid night. “I couldn't fully understand what was going on. I didn't realize it was an earthquake as I wasn't fully awake. Mum was crying and she said Omar, the house is going to collapse and I replied don't worry Mum, just hold me tight and that was the last conversation we ever had,” said Omar, one of the victim of the Izmit earthquake (BBC Science and Nature- Horizon- Earthquake).Thousands of people died from the building collapse which raised a serious question about the construction practices in Turkey

Figure 2: Map of Turkey indicates the epic center region that is under the Golcuk.

damage.jpgFigure 3: arrows indicating location where building collapsing caused death.

Hundreds of buildings collapsed because their foundation were torn apart causing hundreds or more casualities. This earthquake was particularly important to California because it was very similar to the 1906 San Francisco earthquake, which experienced fault offsets of about 15 ft( 4.5 m) within the San Francisco Bay Area( Worldwide Engineering Science Tehcnology- EQE International). However, the construction of Izmit region was considerably below the level of United States. There were approximately 20,000 buildings collapsed or damaged heavily. Most of the buildings were multii-story residential, business or commercial structures built with reinforced concrete, but with unreinforced masonry infill walls.Most of the buildings that have collapsed were either under construction or have been constructed few years back.According to the United States Geological Survey, a very old mosque, in the town of Golcuk, 60 miles east of Istanbul, outperforming more modern buildings surrounding it shown in fig 4. This contrast in structural performance was very striking to the modern construction practices.

mosque.gifFigure 4: an old mosque stood in the middle of modern destroyed buildings.

The reasons behind all this contrast is mainly because the modern constructionists did not meet the design requirement code for the earthquake resistancy. Followings are considered to be the reasons for the building damages: lack of verticle and horizontal reinforing steel, lack of construction oversight by the design engineer(no checks and balaces..), lack of inappropiate construction materials, weak/soft story(open space at the first floors), structural alterations(added floor), long cantilevers with heavy load, and improper construction site (soil condition)- liquified areas or active faults. These reasons caused the buildings to collapse during the earthquake shaking.

The first important step to improve the construction practice is by strenghtening the materials. For example, according to the Earthquake management of Iran, externally bonded fiber reinforced polymer(FRP) laminates and bars have been successfully used to increase the flexural and/ or the shear capacity of recinforced concrete for retrofitting of the civil infrastructure. FRP composites can provide solution for the strenghtening of Unreinforced walls that are subjected to in-plane and out-of-plane overstresses caused by high wind pressure or earthquae loads. Experimental test results have shown that each failure of unreinforced walls was prevented and lessened by using FRP. Another important step to improve the construction practice would be to concentrate more on the architechtural design of the structure, creating a strong foundation for the structure, and minimize the height of the structure depending on the construction site. Improving all these concerns would save alot of building damages created by earthquake.

Figure 5: Video taken two days after the earthquake in Izmit 1999

The Izmit earthquake can be used as lessons for science of earthquakes, earthquake engineering, building code developement and application in earthquake regions, construction quality, and risk management. It was one of the most destructive event that took place in Izmit killing hundreds of thousands people and leaving thousands of people homeless. The main cause for the devastating damages and deaths was the construction practices which can improved by strenghtening the foundation, including stronger materials, and testing the construction sites before building structures.

Work Cited
United States Geological Survey. 1999 Izmit, Turkey Earthquake . 16 May 2007. 31 Oct 2007.

KandiliObservatory & Earthquake Research Institute Boğaziçi University. Izmit Earthquake Turkey.(first report: 18-08-1999 ). 20 Aug 1999. 31 Oct 2007

BBC Science and Nature. Earthquake Storms - transcript . 31 Oct 2007.

Earthquake Management in Iran. Earthquake, the most destructive Force of Nature . 3 January 2004. 25 Nov. 2007

Worldwide Engineering Science Tehcnology- EQE Internationa. Izmit, Turkey Earthquake of August 17, 1999(M7.4). 25 Nov. 2007

Earthquake Severity. What is the Ricther Magnitude?. 9 Oct. 1996. 25 Nov. 2007

Youtube. Hellenic Aid.14 May 2007.25 Nov. 2007

"earthquake." The American Heritage® Dictionary of the English Language, Fourth Edition . Houghton Mifflin Company, 2004. 26 Nov. 2007. <>. Change 0 of 0