MICROZONING OF THE EARTHQUAKE HAZARD IN ISRAEL PROJECT 5 EMPIRICAL DETERMINATION OF SITE EFFECTS FOR THE ASSESSMENT OF EARTHQUAKE HAZARD AND RISK TO BEIT SHEAN & AFULA November, 2005 Job No 569/175/05 Principal Investigator: Dr. Yuli Zaslavsky Collaborators: Galina Ataev, Marina Gorste in, Dr. Avraham Hofstetter, Michael Kalmanovich, Dagmara Giller, Ilana Dan, Nahum Perelman, Tatyana Aksinenko, Vadim Giller, Ion Livshits, and Alexander Shvartsburg Submitted to: Earth Sciences Research Administration National Ministry of Infrastructures & Ministry of Absorption Contract Number: 24-17-017 2 CONTENTS LIST OF FIGURES .....................................................................................................3 LIST OF TABLES .......................................................................................................5 1. INTRODUCTION....................................................................................................8 2. BRIEF REVIEW OF SEVERAL EXPERIMENTAL METHODS FOR SITE EFFECT EVALUATION............................................................................................9 3. H/V SPECTRAL RATIO TECHNIQUE.............................................................13 4. GEOLOGICAL SETTING...................................................................................14 4.1. BET SHEAN........................................................................................................16 4.2. AFULA.................................................................................................................20 5. THE PLANNING OF MICROTREMOR MEASUREMENTS AND DATA ACQUISITION ..........................................................................................................25 6. DATA ANALYSIS.................................................................................................34 7. DISTRIBUTION OF THE FUNDAMENTAL FREQUENCY AND ITS ASSOCIATED H/V SPECTRAL RATIO LEVEL ................................................35 7.1. BET SHEAN........................................................................................................35 7.2. AFULA.................................................................................................................38 8. VALIDATION OF H/V RATIO USING SEISMIC REFRACTION MEASUREMENTS ...................................................................................................43 8.1. BET SHEAN........................................................................................................45 8.2 AFULA..................................................................................................................48 9. ESTIMATION OF SUBSURFACE STRUCTURE USING H/V SPECTRAL RATIOS FROM MICROTREMOR........................................................................52 9.1. BET SHEAN........................................................................................................53 9.1.1. Profile A-A-A'...................................................................................................53 9.1.2. Profile B-B' .......................................................................................................59 9.2. AFULA.................................................................................................................63 9.2.1. Profile A-A'.......................................................................................................63 9.2.2. Profile B-B’ .......................................................................................................66 9.2.3. Profile C-C'.......................................................................................................71 10. IDENTIFICATION OF FAULTS USING H/V SPECTRAL RATIO FROM MICROTREMOR .....................................................................................................72 11. PRELIMINARY SEISMIC ZONATION AND PREDICTION OF ACCELERATION RESPONSE SPECTRA FOR LINEAR AND NON-LINEAR BEHAVIOR OF SOIL SEDIMENTS ......................................................................80 11.1. BET SHEAN......................................................................................................81 11.2. AFULA...............................................................................................................91 12. CONCLUSIONS ..................................................................................................95 ACKNOWLEDGMENT ...........................................................................................97 REFERENCES...........................................................................................................98 3 LIST OF FIGURES Figure 1. Very simplified geological section as an illustration of Nakamura's technique assumptions. ................................................................................................13 Figure 2. A fragment of the Geological map of Israel (1:200 000) in Lower Galilee with the towns of Afula and Bet Shean. ......................................................................15 Figure 3. Geological map of Bet Shean (1:50,000) showing distribution of measurement points. ....................................................................................................17 Figure 4. Lithological section of Sade Nahun-2 and Ain Ashtadri T/6 wells..............18 Figure 5. Geological map of the Afula area.................................................................21 Figure 6. Lithostratigraphyc section for Gan Tapukhim, Gidon-5 and Sarid-1 wells .22 Figure 7. Examples of of seismic station location in Bet Shean..................................28 Figure 8. Examples of seismic station location in Afula .............................................29 Figure 9. Setup of (a) horizontal and (b) vertical transducers for identity test of channels........................................................................................................................30 Figure 10. Ambient noise recordings for the setup of (a) horizontal transducers and (b) their spectral amplitudes without application of "Instrument response removal" procedure......................................................................................................................30 Figure 11. Ambient noise recordings for the setup of (a) horizontal transducers and (b) their spectral amplitudes with application of "Instrument response removal". ...........31 Figure 12. Ambient noise recordings for the setup of (a) vertical transducers and (b) their spectral amplitudes without application of "Instrument response removal" procedure......................................................................................................................32 Figure 13. Ambient noise recordings for the setup of (a) horizontal transducers and (b) their spectral amplitudes with application of "Instrument response removal" procedure......................................................................................................................33 Figure 14. Distribution of H/V resonance frequency (a) and its associated amplitude level (b) within the town of Bet Shean. .......................................................................37 Figure 15. Typical examples of the H/V ratios obtained in the town of Afula............38 Figure 16. Distribution of resonance frequency of the first H/V peak in Afula ..........39 Figure 17. Distribution of amplitude level at first resonance frequency in Afula .......40 Figure 18. Distribution of resonance frequency of the second H/V peak in Afula .....41 Figure 19. Distribution of amplitude level at the second resonance frequency in Afula ......................................................................................................................................42 Figure 20. Velocity depth section along refraction line RL-1. ....................................45 Figure 21. Average H/V spectral ratios obtained at point 162, 202, 81 and 201 along RL-1 refraction line compared with the theoretical transfer functions........................46 Figure 22. Velocity depth section along refraction line RL-2. ....................................47 Figure 23. Average H/V spectral ratio (the red line) for points 199 and 200 superimposed with two theoretical transfer functions calculated assuming different basalt layers as possible reflector. Black and blue lines correspond to reflector represented by upper basalt layer and lower basalt respectively. ................................48 Figure 24. H/V spectral ratio and analytical transfer function for point 115 (Gan Tapukhim well)............................................................................................................49 Figure 25. (a) Velocity-depth section along refraction profile Af-1............................50 Figure 26. (a) Velocity-depth section along refraction profile Af-2 (Afula Hospital); (b) H/V spectral ratio and analytical transfer function for point 295 located at refraction line Af-2 ......................................................................................................51 Figure 27. Velocity-depth section along refraction profile Af-3 .................................51 4 Figure 28. Analytical transfer function and H/V spectral ratio for points (a) 209 (Merhaviya well) and 25 (Gidon 5 well) .....................................................................51 Figure 29. Characteristic 2-D cross section along profile A-A' (Bet Shean)...............54 Figure 30. H/V spectral ratios compared with the theoretical transfer