INDUCED SEISMICITY OF BERKE DAM SITE, SOUTHEASTERN TURKEY

 EYİDOĞAN, H.1, ÖKELER, A.1, GEÇGEL, V.2, and ÜÇOK3

1İstanbul Technical UniversityMining Faculty, Department of Geophysics, Istanbul Turkey

2Kartal Municipality, Istanbul, Turkey3Yapı Ticaret Comp., Adana, Turkey

e mail: eyidogan@itu.edu.tr

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LOCATION & HISTORY

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Berke Dam was constructed on the Ceyhan river which locates at Clician region, southeastern Turkey between upper and lower Ceyhan Basins. The irrigation capacity of the river reaches to 7 billion m3/a. The expected annual hydro-electrical capacity of the river is about 4 billion kWh

Since 1960’s several dams have been constructed on the Ceyhan River. These are Aslantaş (1), Berke (2), Sır(3), Menzelet (4) and Kandil (5) Dams

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The Berke Dam is recently constructed by Turkish ÇUKUROVA ELECTRIC Company and it is the highest dam in Turkey

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BERKE DAM

• Concrete Arc Dam• Height: 201 m • Length of Arc: 270 m• Concrete Volume: 745.000 m3 • Volume Excavated : 700.000 m3

• Energy Capacity: 1669 Gwh/a

The Berke Dam is the highest concerete arc dam in Turkey. It is one of the 16 th highest dam in the world.

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TECTONICS & SEISMICITY

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The Berke Dam is located in Cilician Region which is at the junction of Anatolian, Arabian and African Plates. The Dead Sea Fault (DSFZ) and East Anatolian Fault zones (EAFZ) are the most prominent structural elements in this region. The meeting point of these two major faults forms a complex triple junction, its exact location is still a matter of intense research. The Cilician region is interpreted to develop as a trans-tensional feature developing inside this complex transitional zone. The area is known to have an active historical seismicity.

EAFZ

DSF Z

AB: Adana Basin, CB: Cilician Basin, IB: Iskenderun Basin, LB: Latekia Basin, EF: Ecemiş Fault, GFZ: Goksu Fault Zone, EAFZ: East Anatolian Fault Zone, DSFZ: Dead Sea Fault Zone, YF: Yumurtalik-Karatas Fault Zone, AF: Amanos Fault MS-AN: Misis-Andirin Thrust Belt,

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Aslantas cluster 1999-2001

The recent and accurately relocated earthquakes in Aslantas area display an activity in the north-south direction.

BERKE

The aftershocks of 1998 Adana-Ceyhan earthquake

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BERKE

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M=5.5

Aslantas cluster The events in this cluster give mostly normal fault solutions implying that the area is subject to EW extension governed by the western escape of the Anatolian Block.

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INSTRUMENTS & RECORDS

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SEISMIC INSTRUMENTATION

The seismicity of BERKE Dam site have been monitored by five vertical velocity seismographs during the time period between 1997 and 2003 under the supervision of Çukurova Electric Company and Istanbul Technical University. The stations are autonomous and each station building consists of 1 Hertz vertical seismometer. The seismographs are installed on rock sites to decrease the background noise and well protected against the climatic conditions in specially designed concrete shelters. The three stations were upgraded by changing the conventional analog recorders with GPS controlled digital seismographs in April 2000.

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Shelter SeismometerS-131-D

Recorder Radio Time Unit

Vault

Battery2005

60 seconds

60 seconds

Pn

Pg

Pg

Sg, Rg

SAMPLE RECORDS

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INDUCED SEISMICITY

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SEISMICITY BEFORE FILLING (1997- 2001 AUGUST)

The magnitudes of these events range between 1.0 and 3.5 and only the events with RMS error smaller than 1.0 is included

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SEISMICITY AFTER FILLING (2001 SEPTEMBER - 2003)

The magnitudes of these events range between 0.5 and 3.0 and only the events with RMS error smaller than 1.0 is included

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Water Height (m) Number of Earthquakes

Time

INDUCED SEISMICITY

Missing data

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PROBLEMS ENCOUNTERED

• Unstable main electricity and disruption• Charging the batteries (solar cells recomended)• Thunderbolt• Conventional analog paper recorders

– Stylus– Timing

• Digital Recorders– Hardware very fragile to power deficiencies and unstable

voltage conditions– High power consumption of hard disks

• Training of domestic operators

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CONCLUSIONS

• The Berke Dam locates in the trans-tensional region where the Dead Sea Fault, East Anatolian Fault and Misis-Andırın Thrust Belt joins

• West of dam site, regional seismicity displays a north-south oriented clustering which gives mostly normal fault solutions with small strike-slip component implying that the area is subject to EW extension

• Berke Dam site is quiescent in the time periods betwen 1997 and August 2001 before filling the dam

• Following the rise of the water level in reservoir area the induced seismicity increased rapidly with a couple weeks delay

• The induced activity mainly occurred at the mid-part of the narrow reservoir area

• Small changes of the water level triggered seismic activity

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THANK YOU

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