Sites visited by the geotechnical engineering team:

1. Part 1: 23 October 2011 Van-Tabanlı Earthquake Geotechnical Field ObservationsMETU Reconnaissance Team Geotechnical GroupZ. Gülerce, K.Ö. Çetin, M. T. Yılmaz, N.H. Sarıhan, Y.S. Ünsever, S. Ünsal, S. Sağlam, M.A. Sandıkkaya, M. Türkoğlu

2. Sites visited by the geotechnical engineering team: Immediately after the mainshock, a reconnaissance team from METU Geotechnical Engineering Division visited Van, Erciş and many other small towns where most of the damage occurred. Group 1 Group 2

3. Most of the liquefaction-related failures were observed in the near vicinity of the Lake Van.

4. Particle size distribution analysis results of samples taken from liquefied sites Group 1 Group 2

5. Lateral Spreading observed in Topaktas Village along Karasu River

6. Failure of natural slopes in shores of Lake Van

7. Failure of natural slopes

8. Rock fall to Van-Ercis Highway

9. Van-Ercis Highway East Lane Slope Failure

10. Van-Ercis Highway East Lane Slope Failure Possible center of circular failure surface Possible circular failure surface from field observations • Soil type: SM, ϕ=22 ° Static FS=1.90 • Dynamic FS=1.01 and PGA=0.4g

11. Funding for the field trip was provided by METU and Earthquake Engineering Research Center which is highly appreciated. We would like to thank to Van YuzuncuYil University and IMO for their support. Visual material for this presentation is used in METU_EERC and GEER earthquake reconnaissance reports.

12. Part 2: Performance of NGA-W1 Ground Motion Model Predictions on Recent Events in Turkey: 2010 Elazığ and 2011 Van Earthquakes Zeynep Gülerce and Emre Akyüz

13. March 08, 2010Elazığ-Kovancılar Earthquake (MW=6.1) • Ocurred on left-lateral strike-slip East Anatolian Fault (EAF) which is one of the two major active fault systems in Turkey • 42 people lost their lives and 137 were injured during the event Figure taken from METU-EERC Preliminary Report

14. Prediction peformance of NGA-W1 Models at PGA: CB 2008 BA 2008 ID 2008

15. Prediction peformance of NGA-W1 Models at PGA: CY 2008 AS 2008

16. Prediction peformance of NGA-W1 Models at 1 sec: CB 2008 BA 2008 ID 2008

17. Prediction peformance of NGA-W1 Models at 1 sec: CY 2008 AS 2008

18. October23, 2011 Van-Tabanlı Earthquake (MW =7.1) • Reverse mechanism (rare in Turkey) • Only 3 recordings within 200 km from the mainshock Figure taken from Gülerce et al., 2012

19. Prediction peformance of NGA-W1 Models at PGA: CB 2008 BA 2008 ID 2008

20. Prediction peformance of NGA-W1 Models at PGA: CY 2008 AS 2008

21. Prediction peformance of NGA-W1 Models at 1 sec: CB 2008 BA 2008 ID 2008

22. Prediction peformance of NGA-W1 Models at 1 sec: CY 2008 AS 2008

23. Is this result expected?? Due to the limitations of the PEER-NGA project and the missing parameters in The Turkey GM dataset, a very small number of ground motions recorded during the earthquakes occurred in Turkey was included in the NGA -W1 database (Chiou, 2008) Number of recordings included in the dataset

24. Even though a large amount of data is available, a whole database with complete source metadata and recording station information was difficult to establish during the project. daphne.deprem.gov.tr 4607 sets of ground motions recorded during the earthquakes occurred in Turkey between 1976-2007 were gathered and delivered through the project web-site.

25. The starting point: TSGM (Daphne) Database • TSGM database includes 4067 sets ofrecordings from 2996 events. • Only 173 of these events are magnitude 5 or bigger. • During these 173 events 685 recordings were taken. • Small magnitude events (M<5) only if 3 or more recordings are available. • The moment magnitude for 119 of events estimated from ML using Akkar et al. 2010 • No site information (Vs30 or site classification) could be found for 431 recordings (estimated from NGA-W1 database or removed) • The style of faulting for 68 recordings are estimated from the mechanisms of other earthquakes in the sequence or due to the dominant mechanism of the region. • If the distance measures were missing (96 recordings) they were estimated from the fault plane solutions or Rhypo and Repi values.

26. Final Comparison Dataset Final Checks: • Distance metrics with NGA-W1 database • Depth to top estimation • Declustering (Thanks to Katie Woddell from PG&E) • GmRotI50 consistency with the NGA-W1 database

27. Evaluating the Magnitude, Distance and Vs30 scaling of the dataset: Residual Mean Offset Event Term Intra-Event Residual +…

28. Turkey-Adjusted NGA-W1 Models: • All five NGA-W1 models are evaluated using the comparison dataset by analysis of model residuals. • Inter-event residuals vs. magnitude plots showed significant overestimation for small-to-moderate magnitudes! Corrected by adding adjustment functions for Mw<6.75. Well-constrained pieces of the models (Mw>6.75) were preserved.

29. Turkey-Adjusted NGA-W1 Models: • Intra-event residuals vs. distance plots suggested no trend within the applicability range of the NGA-W1 models for tectonic regions other than Western US (100 kilometers) • The large distance scaling (gamma-term) were adjusted (100-200 km).

30. Turkey-Adjusted NGA-W1 Models: • AS2008 and CY2008 models slightly under-predict the ground motions in the Turkey comparison dataset at stiff soil/engineering rock sites but this effect diminishes as Vs30 decreases. Aftershocks.... • Corrected by adding adjustment functions for Vs30 >450 m/s. 5 new models for Turkey (TR-Adjusted NGA-W1 models) will be published soon. (Gülerce, Kargıoğlu and Abrahamson, 2013. Submitted to Earthquake Spectra).