The examination of earthquake triggering mechanism of Atatürk dam area, the space and time distribution of the epicenters and solutions of the fault mechanisms belonging to the earthquake occurred in September 3, 2008 (02:2 UTC, ML=5.2) and its aftershocks (ML=4.6 and ML=4.0), and their correlation with the surrounding tectonic structure.

1. CORRELATION BETWEEN WATER LEVEL
DECREASE IN ATATURK DAM, TURKEY and Mw
5.0 EARTHQUAKE ON SEPTEMBER 3, 2008
Haluk EYİDOĞAN, Veli GEÇGEL and Zumer PABUÇCU
e mail: eyidogan@itu.edu.tr

2. The examination of earthquake triggering mechanism of
Atatürk dam area, the space and time distribution of the
epicenters and solutions of the fault mechanisms belonging to
the earthquake occurred in September 3, 2008 (02:2 UTC,
ML=5.2) and its aftershocks (ML=4.6 and ML=4.0), and their
correlation with the surrounding tectonic structure.
OBJECTIVE

3. Atatürk Dam Features
• Atatürk Dam is on the Fırat (Euphrates) river and is the
fourth biggest clay cored rock-fill dam in the world
regarding water capacity and amount of electricity
produced.
• The main features of the dam are as follows: Dam height –
170m; Crest length – 1670m; Crest level – 549m;
Maximum base width – approx. 900m; Dam volume – 84 x
106m3; Reservoir volume – 48 km3; Resrvoir area- 817
km2; Installed capacity – 2400MW; Annual energy
generation – 8100GWh.
• The maximum and minimum operation reservoir levels are
542m and 526m asl respectively.

4. Tectonic development of the area is
governed by convergence of the
Arabian and African Plates towards
the Anatolian Plate. The Atatürk Dam
is located at 50 km southeast of East
Anatolian Fault zone which is the
most prominent structural elements in
the region. Bozova Fault was issued
on the Active Fault Map of Turkey in
1992 and Geology Map of Turkey.
Right-lateral strike-slip Bozova Fault
is located 1.5 km south of the dam
and has a length of about 55-60 km

5. The dam was started to be filled following the
year of 1989. The reservoir level reached
535m asl in March 1994 and has varied
between 526m and 537m asl since then. The
maximum and minimum operation reservoir
levels are 542m and 526m asl, respectively.

6. Atatürk Dam site has no large seismic activity in historical periods. It was seen that
the triggered earthquake activity, obtained from the Kandilli Observatory and
Earthquake Research Institute (KOERI) database, was evidently increasing following
the year of 1994. Although KOERI stations are distant and few in number, the
frequency of the earthquakes increased rapidly since 1994 following the highest level
of water reach in the dam.
2
2,5
3
3,5
4
4,5
5
01.01.1985
01.01.1986
01.01.1987
01.01.1988
01.01.1989
01.01.1990
01.01.1991
01.01.1992
01.01.1993
01.01.1994
01.01.1995
01.01.1996
01.01.1997
01.01.1998
01.01.1999
01.01.2000
01.01.2001
01.01.2002
01.01.2003
01.01.2004
01.01.2005
01.01.2006
01.01.2007
01.01.2008
Time
Magnitude
0
100
200
300
400
500
600
WaterLevelinMeters
31.12.2008
Missing Data ?
0
5
10
15
20
25
30
35
40
01.01.1992 01.01.1994 01.01.2000 01.01.2004 01.01.2006 01.01.2007 01.01.2008 31.05.2009
Time (Year)
NumberofStations
0
5
10
15
20
25
30
35
40
CumulativeNumberofStations
Number of the earthquake
stations present in the area
of 1x1 degree
The number of the earthquake stations did not
undergo a great change until the TURDEP project
activities (Inan et al., 2007) started for the region.
30 seismic stations were installed in the region,
mainly along the EAFZ. This helped to increase the
accuracy of the EQ parameters for the activity
around the dam.

7. Fault mechanism solutions of the earthquakes with a
magnitude of ML≥ 4.0 and the seismicity in the time period
between 2007-2009 (TURDEP Project Database)
29-Nov-06
17-Jun-07
3-Jan-08
21-Jul-08
6-Feb-09
25-Aug-09
13-Mar-10
1 2 3 4 5
Time vs Magnitude (2007-2009)
0
1
2
3
4
5
0.00 0.20 0.40 0.60 0.80 1.00
Md vs RMS Residuals
Md

9. The water level decreased rapidly in the summer of 2007, did not increase in the 2008
winter because of insufficient rainfall, and decreased even more in the summer of 2008.
On September 3, 2008, in the days when the total decrease was 6 m, an earthquake with a
magnitude of Mw=5.0 (ML=5.2) occurred in the northeast of the body of the dam; and
aftershocks were experienced following the earthquake.
525
526
527
528
529
530
531
532
533
534
535
536
537
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
01/01/2007
01/02/2007
01/03/2007
01/04/2007
01/05/2007
01/06/2007
01/07/2007
01/08/2007
01/09/2007
01/10/2007
01/11/2007
01/12/2007
01/01/2008
01/02/2008
01/03/2008
01/04/2008
01/05/2008
01/06/2008
01/07/2008
01/08/2008
01/09/2008
01/10/2008
01/11/2008
01/12/2008
01/01/2009
01/02/2009
01/03/2009
01/04/2009
01/05/2009
01/06/2009
01/07/2009
01/08/2009
01/09/2009
01/10/2009
01/11/2009
01/12/2009
WaterLevelinMeters
Magnitude
Time
3 September 2008
Mw=5.0
817 km2 x 6.25 m
Amount of drawdown ≈ 5 billion ton

10. * The strike slip mechanism at the ATATÜRK DAM site
is due to shear-slip long the existing fractures as a result of
increased maximum or minimum principal stresses.
* Shear stress in the region is probably close to the rock-
mass frictional strengths and that a small perturbation of
the shear stress field triggered the magnitude 5.0 activity.
σ R =σL – σS
σ3
σ1Water level
σ1>σ3
N

11. CONCLUSIONS
• Considering the stress changes caused by the mechanism
characteristics of the September 3, 2008 earthquake, ambient
stress distrubition in the region, the locations of the aftershocks,
and drastic decrease in the water level, the earthquake occurred
on September 3, 2008 was interpreted as a triggered earthquake
• It could be stated that fast and significant amount of water load
decrease in the Ataturk Dam caused the exceeding of the critical
tension level by changing the ambient NW-SE directioned
compressional stress or NE-SW directioned tensional stress and
finally caused an earthquake with a magnitude of Mw=5.0.

12. CONCLUSIONS
• No concrete conclusion was reached regarding the correlation
of the triggered seismicity, consisting of September 3, 2008
earthquake and its aftershocks, with the active Bozova Fault.
• It should be pointed out that the possibility that new changes
in the tectonic forces around the dam and in depths and pore
pressure, due to the water level changes in significant
amounts, would cause stress effects that would trigger the
Bozova Fault should be evaluated. The Bozova Fault that is
located significantly close to the body of the dam should be
urgently and multi-dimensionally examined.

13. We would like to offer our acknowledgements to
Turkish Directory of State Water Affairs (DSI)
and TUBITAK Marmara Research Center-
Institute of Earth and Marine Science (MRC-
IEMS) for their support for data. Zumer Pabuccu
and Onur Tan made contributions for the
acquisition of raw data, Aylin Tan spent efforts to
supply some articles and documents and Argun
Kocaoglu helped in installing and compiling
softwares on my computer.

14. THANK YOU