1. Turkey Earthquake Risk Model Financing the Risks of Natural Disasters World Bank Washington, DC, June 2-3, 2003 Dennis E. Kuzak Senior Vice President, EQECAT, Inc

2. Overall Model Components Portfolio of Insured TCIP Exposures Turkish Census and building stock data, plus TCIP information Seismotectonic Model - fault/source locations, magnitudes, frequencies Professor Erdik, USGS Research Papers, historical catalogs Seismic Hazard - Ground Shaking Attenuation Functions, Local Soil Conditions Vulnerability Historical Building Performance, Engineering Analysis, Turkish construction practices Damage and Financial Loss Policy Deductibles, Limits

3. Seismic Hazard Modeling Methodology  Source zonation model (location)  Recurrence model (size and frequency)  Ground motion model (ground shaking)  Hazard curve (ground shaking vs. probability)  Soil model (ground shaking amplification) The location, size, and frequency of rare catastrophic earthquakes and their associated ground shaking are modeled using a Probabilistic Seismic Hazard Analysis (PSHA), which is composed of the following elements:

4. Tectonic Setting of Turkey White

5. Quaternary Faults of Turkey

6. Legend: M 5.0-5.9 (purple); M 6.0-6.9 (blue); M 7.0+ (red) Earthquakes in Turkey, 1904-1992

7. Earthquake Sources of Turkey White Source: Erdik et al. (1999), “Assessment of earthquake hazard in Turkey and neighboring regions,” Annali di Geofisica, Vol. 42, pp. 1125-1138.

8. Seismic Hazard Map of Turkey PGA (g) with a 10% Probability of Exceedance in 50 Years (475-year Return Period) on soft rock White Istanbul Ankara Black Sea Mediterranean Sea Source: Erdik et al. (1999), “Assessment of earthquake hazard in Turkey and neighboring regions,” Annali di Geofisica, Vol. 42, pp. 1125-1138.

9. EQECAT Source Zonation Model  Basic area-source model from Erdik et al. (1999)  Large characteristic earthquakes (M  6.5):  North Anatolian Fault (NAF)  Northern NAF (NNAF; Marmara Sea)  Southern NAF (SNAF; south of Marmara Sea)  Distributed faulting on NNAF and SNAF  Smaller earthquakes included as NAF, NNAF and SNAF background seismicity zones

10. Marmara Sea Region NAF SNAF NNAF

11. North Anatolian Fault System (NAF)  Potentially the largest contributor to seismic hazard in Istanbul and northwestern Turkey  Ruptures in a sequence of large earthquakes  Previously known rupture sequences occurred in 967- 1050 and 1254-1784  Latest sequence began in 1939 and is still in progress  Latest events in current sequence are the 1999 M 7.4 Izmit and M 7.2 Duzce earthquakes  Next event in sequence is likely to be in Marmara Sea (Yalova and/or Prince’s Islands Faults?)

12. Rupture History of the NAF to 1992 Note: Mean repeat time is now estimated to be 225 years east of NNAF/SNAF split and 280 years west of this split (Stein, personal comm., 2000; Parsons et al., 2000)

13. EQECAT Recurrence Model  Area and background sources  Fault sources:  North Anatolian Fault (NAF)  Northern NAF (NNAF; Marmara Sea)  Southern NAF (SNAF; south of Marmara Sea)

14. Recurrence: Area and Background Sources  Earthquake catalog from regional sources:  All magnitudes converted to moment magnitude  Foreshocks, aftershocks and swarms removed  Corrected for incompleteness  Exponential (Gutenberg-Richter) recurrence law  Maximum magnitude from seismicity/tectonics

15. Recurrence: Fault Sources  Characteristic earthquake recurrence law  Recurrence rates from previous historic events  Magnitudes on NAF from last historic event  Magnitudes on NNAF from length/historic events  Magnitudes on SNAF from largest historic event  Time-dependent probability on NAF and NNAF

16. EQECAT Time-Dependent Model Definition of Time-Dependent Probability Time-dependent probability is the conditional probability that an earthquake will occur on a fault within some specified period of time in the future (i.e., 2000 to 2030), given that a similar earthquake has occurred on this fault at some known time in the past

17. Causes of Time-Dependent Behavior  Secular stress increase due to long-term strain accumulation  Permanent stress increase or decrease due to stress interaction from an earthquake on a nearby fault  Transient stress increase or decrease due to stress interaction from an earthquake on a nearby fault (decays with time)

18. Time-Dependence from Secular Stress Lognormal Probability Model Last Earthquake PARAMETERS T e = Elapsed Time  T = Exposure Period Conditional Probability = A/(A + B) A B Note: We use recurrence intervals of 225 years east of NNAF/SNAF split and 280 years west of split; exposure period of 1 year; elapsed time from last historic event

19. Time-Dependence from Secular Strain Sensitivity to Total Variability Note: We use  = 0.5

20. Time-Dependence from Fault Interaction Transient Stress for NAF Source: Parsons et al. (2000)

21. Time- Dependence from Fault Interaction  Progressive Effect of 1939-1992 Earthquake Sequence Source: Stein et al. (1997)

22. Time- Dependence from Fault Interaction  Effect of 1999 Izmit Earthquake Source: Parsons et al. (2000)

23. Time-Dependence from All Effects Faults within 50 km of Istanbul Source: Parsons et al. (2000); Our results give 50% smaller probability

24. Time-Dependence from All Effects Istanbul Earthquake Probabilities of M  7 for Faults within 50 km of Istanbul Beginning in May 2000 (Interaction includes Secular and Interaction Stress Effects) Note: 30-year time-averaged (Poisson) probability is 20  10% Source: Parsons et al. (2000); Our results give 50% smaller 1-year combined probabilities

25. EQECAT Ground Motion Model  Four attenuation relationships for shallow crustal earthquakes:  Abrahamson and Silva (1997)  Boore et al. (1997)  Campbell (1997)  Sadigh et al. (1997)  One attenuation relationship for subduction earthquakes:  Youngs et al. (1997)  1999 Izmit earthquake validation

26. PGA Estimate for 1999 Izmit Event Note: PGA in g; Values are consistent with limited strong-motion recordings

27. EQECAT Soil Model  NEHRP soil classifications (A-E) were derived from a 1:500,000-scale geologic map of Turkey  Correlation with geology was based on extensive studies relating shear-wave velocity and geologic units in California  PGA amplification factors were based on empirical and theoretical studies relating shear-wave velocity and amplification

28. Turkish Soil Map

29. EQECAT Hazard Results  Seismic hazard curves:  Istanbul (Bakirkoy)  Izmit  Ankara  Seismic hazard maps:  All of Turkey  Marmara Sea Region

30. Seismic Hazard Curves  Lowest hazard in Ankara, located in more stable central region of Turkey  Hazard in Izmit is approximately the same as that in Istanbul (Bakirkoy) because:  Time-dependent probability effects have increased hazard in Istanbul  Time-dependent probability effects have decreased hazard in Izmit Soft Rock

31. Seismic Hazard Map for Turkey 0.05 - 0.10 0.10 - 0.15 0.15 - 0.20 0.20 - 0.25 0.25 - 0.30 0.30 - 0.35 0.35 - 0.40 0.40 - 0.45 0.45 - 0.50 0.50 - 0.55 0.55 - 0.60 0.60 - 0.65 0.65 - 0.70 0.70 - 0.75 0.75 - 0.80 0.80 - 0.85 0.85 - 0.90 PGA (g) PGA with 10% Probability of Exceedance in 50 Years (475-year Return Period) Soft Rock

32. Seismic Hazard Map for Marmara Sea PGA with 10% Probability of Exceedance in 50 Years (475-year Return Period) 0.05 - 0.10 0.10 - 0.15 0.15 - 0.20 0.20 - 0.25 0.25 - 0.30 0.30 - 0.35 0.35 - 0.40 0.40 - 0.45 0.45 - 0.50 0.50 - 0.55 0.55 - 0.60 0.60 - 0.65 0.65 - 0.70 0.70 - 0.75 0.75 - 0.80 0.80 - 0.85 0.85 - 0.90 PGA (g) Soft Rock

33. Building Vulnerability  Good building codes- poor construction practices  Non ductile concrete frames, soft story  Limited/No claims data for residential multi-family  EQECAT approach- use aggregate residential damage data from Izmit, select damage curve consistent with Izmit data.

34. Summary  Turkish Model incorporates current research on time-dependent studies of North Anatolian Fault  Raises hazard in Istanbul  Lowers hazard east of Izmit epicenter  Recognizes uncertainty in NAF location in the Marmara Sea  Incorporates poor building practices into vulnerability assumptions  Fully probabilistic damage and loss model consistent with other EQECAT earthquake models for the US, Japan, Taiwan, etc.

35. TCIP RISK ANALYSIS RESULTS Portfolio exposures estimated as of 31-10-2002 Estimated Annual Damage =.138% (1.38 per mill)