GROUND MOTION SIMULATIONS AT RAPID RESPONSE SITES IN ISTANBUL, TURKEY

1. GROUND MOTION SIMULATIONS AT RAPID RESPONSE SITES IN ISTANBUL, TURKEY Mathilde Bøttger Sørensen1, Nelson Pulido2, Anibal Ojeda3, Kuvvet Atakan1, Mustafa Erdik4 1Department of Earth Science, University of Bergen, Norway, 2Earthquake Disaster Mitigation Research Center EDM, NIED, Kobe, Japan, 3INGEOMINAS, Bogota, Colombia, 4Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul, Turkey.

2. Westward migration of earthquakes on the NAF after Barka et. al. (2002)

3. This study • Hybrid method for simulating ground motions due to finite-extent earthquake source in Marmara Sea • Pulido and Kubo (2004): Deterministic at low frequencies, semi-stochastic at high frequencies • Simulation on irregular grid of Istanbul Earthquake Rapid Response and Early Warning System stations

4. Istanbul Earthquake Rapid Response and Early Warning System

5. Rapid Response system • 100 accelerometer stations • When triggered, station produces spectral acceleration at a number of frequencies, 12 Hz filtered PGA and PGV • Data sent pr SMS every 20 s • Main data center produces shake, damage and casualty maps, which are available to the end-users within 5 min

6. Istanbul Earthquake Rapid Response and Early Warning System

7. Early Warning system • 10 accelerometer stations close to the Marmara fault • When several stations triggers an alarm is declared • Alarm level is sent to critical facilities, which can then shut down before the earthquake strikes

8. Use of simulation results • Calibration of Rapid Response system parameters • Calibration of Early Warning system parameters • Realistic scenario input for producing shake, damage and casualty maps • Comparison to recorded earthquakes

9. Ground motion evaluation from asperity model

10. Ground motion simulation technique • Low frequency: Deterministic wave propagation from an asperity model in a flat layered velocity structure (Discrete Wave Number Method, Bouchon 1981) • High Frequency: Semi-Stochastic Simulation based on an asperity model . The model combines the stochastic methodology of Boore (1986) with the empirical Green’s function method of Irikura (1986), and a high frequency radiation pattern model (Pulido et. al 2002).

11. Scenario earthquake Active tectonic map of the Marmara Sea (Okay et. al 2000)

12. Source parameters

13. Velocity model

14. PGV results

15. PGA results

16. PGV

17. PGA

18. Waveform exampleAvcilar district

19. GM3D

21. Tectonic Setting Marmara Sea Region Okay et. al 2000

22. Scenario Earthquake Active tectonic map of the Marmara Sea (Okay et. al 2000)

23. Scenario Earthquake 1b Active tectonic map of the Marmara Sea (Okay et. al 2000)

24. Scenario Earthquake 2 Active tectonic map of the Marmara Sea (Okay et. al 2000)

25. Scenario Earthquake 3 Active tectonic map of the Marmara Sea (Okay et. al 2000)

26. High Frequency Radiation Pattern Model P-wave SH-wave SV-wave Low Frequency < 1Hz Non-spherical High Frequency Spherical > 3 Hz The region between 1 to 3 Hz is a transition between the theoretical radiation of a double couple to a completely stochastic radiation

27. Asperities and Seismicity After Gurbuz et. al. (2000), Tectonic fault model from Okay (2000)

28. Fault Segments Parameters The depth seismogenic zone is 20 km Hypocenter located at a depth of 10 km

29. Variability of the Simulated Ground Motion

30. Simulated Spectra and Turkish Seismic Code Turkish Seismic Code, Aydinoglu (1998)

31. Deterministic vs Probabilistic PGA Distribution PGA from scenario earthquake 1a PGA values for a 10% of excedance in 50 years (Atakan et. al. 2002)

32. Avcilar district

33. Sultanahmet district