12 NOVEMBER 1999 DUZCE EARTHQUAKE
An earthquake of moment magnitude 7.1 has taken place to the immediate south of the Duzce, a town of population 80,000 in Bolu province. The earthquake took place along the Duzce Fault at the section indicated on the map (marked with red color) prepared by A.Barka and his colleagues. As such, except its timing, it was no surprise. It actually could have been considered as one of the segments (fifth segment) of the Aug.17 earthquake if it were to rupture in succession with the Aug.27 earthquake phenomenon.
First and preliminary findings indicate fault a fault rupture of about 30km with predominantly right lateral offsets. Right-Lateral strike-slip rupture between Duzce (Golyaka) and Bolu ( see figures ) . The offsetts, reported to be about 1.5. at Duzce (west end) reach up to 3m at towards Bolu (east end) .
There are few strong ground motion stations operated by the General Directory of Disaster Affairs in the vicinity of the earthquake affected area. The peak ground accelerations recorded are 24 mg at Sakarya (Adapazarý) and 804 mg at Bolu. These strong motion records can be downloaded from http://angora.deprem.gov.tr/ftpt.htm. The peak ground accelerations obtained from our array are indicated in the figure.
The is extensive damage at Duzce, Kaynasli, Bolu, Akcakoca, Zonguldak, Adapazari. ( see figures ) Most of the damage is concentrated in Kaynasli a small town on the main highway between Duzce and Bolu. Loss of life in Duzce seems to concentrate in few collapsed buildings that were "lightly" damaged in the August 17 earthquake, superficially repaired and later inhabited. Loss of life is somewhat limited since the buildings damaged in the August 17 earthquake were already vacated. Total number of heavily damaged buildings is in the vicinity of 200. 550 people lost their lives (as of 17-11-1999) and over 3000 people were hospitalized with injuries. Fire damage due to overturning of coal and wood burning stoves and explosion of bottled LNG. Well coordinated and effective rescue and first aid operations with participation from all over the country and abroad.
The main highway system between Istanbul Ankara closely follows the Duzce Fault and the whole area is mountainous and highly prone to landslide hazard. At Bakacak section (between Kaynasli and Bolu) of the main highway between Istanbul and Ankara two lanes of the four-lane highway collapsed due to land slide for a section of about 200m. Fortunately no vehicle traffic were on the highway at the moment of collapse see figures. The major viaducts in the regions are structurally intact except possible damaged to the elastomeric bearings under the decks. The Bolu highway tunnel is under constraction near the raptured area.
Motion Acceleration Records by KOERI Earthquake Engineering