Investigating the Correlation Between the High-Frequency Spectral Attenuation Parameter Kappa and Vs30 in the Central Aegean Region

Öz

The Aegean Region has a high risk of seismic activity because of its active fault lines and dense population. To assess this risk accurately, it is essential to understand the high-frequency spectral decay parameter known as "kappa" (κ), which reflects local site conditions. In this study, 1056 records of 291 earthquakes collected from 43 stations in the Central Aegean Region, connected to the Turkish National Strong Ground Motion (TR-KYH) Observation Network operated by AFAD, with known Vs30 (average shear-wave velocity in the top 30 meters) values, were used. Using the Central Aegean subset of a large dataset compiled for Western Anatolia, a regional κ model was created, incorporating site-specific κ values for various site classes and a common distance dependence. The site-specific attenuation parameter (κ0) for each station was then calculated by removing the regional attenuation effect. An analysis of the spatial distribution of κ0 and Vs30 values shows that alluvial sites in the Aegean basins usually have high κ0 and low Vs30 values. In contrast, stiff soil and rock sites near the horst structures exhibit lower κ0 and higher Vs30 values. The results indicate a general negative correlation between κ0 and Vs30, despite significant scatter. This finding suggests that κ0 could potentially be used as a proxy for site classification at sites where Vs30 values are unknown. However, further research with larger datasets representing a wider range of site classes is necessary to find a more reliable and significant relationship between these two parameters. Validation of such a relationship would facilitate the widespread use of κ0 in earthquake engineering applications.

Anahtar Kelimeler

• High-frequency Spectral Attenuation
• Site Classification
• Vs30 Velocity
• Central Aegean Region

Orta Ege'de Yüksek Frekanslı Spektral Sönümleme Parametresi Kappa ile Vs30 Arasındaki İlişkinin Araştırılması

Öz

Aktif fay hatları ve yoğun nüfusu nedeniyle Ege Bölgesi yüksek deprem riski taşımaktadır. Bu riskin doğru şekilde değerlendirilmesinde, yerel zemin koşullarını yansıtan yüksek frekanslı spektral sönümleme katsayısının ("kappa", ) bilinmesi kritik öneme sahiptir. Bu çalışmada, AFAD tarafından işletilen Türkiye Ulusal Kuvvetli Yer Hareketi (TR-KYH) Gözlem Ağı’na bağlı, Orta Ege Bölgesi’nde yer alan ve Vs30 (ilk 30 m’deki ortalama kayma dalgası hızı) değerleri bilinen 43 istasyonda kaydedilmiş 291 depreme ait 1056 adet kayıt kullanılmıştır. Batı Anadolu için daha önce derlenmiş geniş bir veri setinin Orta Ege Bölgesi'ni temsil eden alt grubu kullanılarak, çalışma sahasındaki zemin sınıflarına özgü κ değerlerini ve ortak bir uzaklık bağımlılığını içeren bölgesel bir κ modeli geliştirilmiştir. Ardından, bölgesel sönümleme etkisi arındırılarak her bir istasyona özgü yerel sönümleme parametresi (0) hesaplanmıştır. 0 ve Vs30 değerlerinin mekansal dağılımı incelendiğinde, Ege havzalarındaki alüvyon zeminlerin genellikle yüksek 0 ve düşük Vs30 değerlerine sahip olduğu; buna karşın bölgesel horst yapılarına yakın sıkı zemin ve kayaçların ise daha düşük 0 ve daha yüksek Vs30 değerleri sergilediği görülmektedir. Sonuçlar, κ0 ile Vs30 arasında belirgin bir saçılım gözlense de genel olarak negatif bir korelasyonun varlığına işaret etmektedir. Bu bulgu, Vs30 değerinin bilinmediği sahalarda κ0’ın potansiyel bir zemin sınıflandırma parametresi olarak kullanılabileceğini göstermektedir. Ancak iki parametre arasında daha güvenilir ve anlamlı bir ilişki kurabilmek için farklı zemin gruplarını temsil eden daha kapsamlı veri setleriyle çalışmaların derinleştirilmesi şarttır. Böyle bir ilişkinin doğrulanması, κ₀'ın deprem mühendisliği uygulamalarında yaygın kullanımının önünü açacaktır.

Anahtar Kelimeler

• Yüksek Frekanslı Spektral Sönümleme
• Zemin Sınıflandırması
• Vs30 Hızı
• Orta Ege Bölgesi

Kaynakça

1. Kurtulmuş TÖ, Yerlikaya-Özkurt F, Askan A. Modeling of kappa factor using multivariate adaptive regression splines: application to the western Türkiye ground motion dataset. Natural Hazards 2024. doi:10.1007/s11069-024-06535-y.
2. Anderson JG, Hough SE. A model for the shape of the fourier amplitude spectrum of acceleration at high frequencies. Bulletin of the Seismological Society of America 1984;74:1969-1993. doi:10.1785/BSSA0740051969.
3. Atik LA, Kottke A, Abrahamson N, Hollenback J. Kappa (κ) scaling of ground-motion prediction equations using an inverse random vibration theory approach. Bulletin of the Seismological Society of America 2014;104:336-346. doi:10.1785/0120120200.
4. Bora SS, Cotton F, Scherbaum F, Edwards B, Traversa P. Stochastic source, path and site attenuation parameters and associated variabilities for shallow crustal European earthquakes. Bulletin of Earthquake Engineering 2017;15:4531-4561. doi:10.1007/s10518-017-0167-x.
5. Ktenidou OJ, Gélis C, Bonilla LF. A study on the variability of Kappa (κ) in a borehole: Implications of the computation process. Bulletin of the Seismological Society of America 2013;103:1048-1068. doi:10.1785/0120120093.
6. Tsai CCP, Chen KC. A model for the high-cut process of strong-motion accelerations in terms of distance, magnitude, and site condition: An example from the Smart 1 array, Lotung, Taiwan. Bulletin of the Seismological Society of America 2000;90:1535-1542. doi:10.1785/0120000010.
7. Purvance MD, Anderson JG. A comprehensive study of the observed spectral decay in strong-motion accelerations recorded in Guerrero, Mexico. Bulletin of the Seismological Society of America 2003;93:600-611. doi:10.1785/0120020065.
8. Drouet S, Cotton F, Guéguen P. VS30, κ, regional attenuation and Mw from accelerograms: application to magnitude 3-5 French earthquakes. Geophys J Int 2010;182:880-898. doi:10.1111/j.1365-246X.2010.04626.x.

9. Iwakiri K, Hoshiba M. High-frequency (10 Hz) content of the initial fifty seconds of waveforms from the 2011 off the Pacific coast of Tohoku earthquake. Bulletin of the Seismological Society of America 2012;102:2232-2238. doi:10.1785/0120110241.
10. Ktenidou OJ, Cotton F, Abrahamson NA, Anderson JG. Taxonomy of κ: a review of definitions and estimation approaches targeted to applications. Seismological Research Letters 2014;85:135-146. doi:10.1785/0220130027.
11. Askan A, Sisman FN, Pekcan O. A regional near-surface high frequency spectral attenuation (kappa) model for northwestern Turkey. Soil Dynamics and Earthquake Engineering 2014;65:113-125. doi:10.1016/j.soildyn.2014.06.007.
12. Kurtulmus TO, Akyol N. Separation of source, site and near-surface attenuation effects in western Turkey. Natural Hazards 2015;77:1515-1532. doi:10.1007/s11069-015-1660-7.
13. Tanırcan G, Dikmen SÜ. Variation of high frequency spectral attenuation (Kappa) in vertical arrays. Soil Dynamics and Earthquake Engineering 2018;113:406-414. doi:10.1016/j.soildyn.2018.06.016.
14. Biro Y, Siyahi B, Akbas B. Spectral decay parameter (κ) analysis for a single fault source and an automatic selection procedure for spectral flattening frequency (fx). Soil Dynamics and Earthquake Engineering 2022;153:107122. doi:10.1016/j.soildyn.2021.107122.
15. Altindal A, Askan A. Predictive kappa (κ) models for Turkey: Regional effects and uncertainty analysis. Earthquake Spectra 2022;38:2479-2499. doi:10.1177/87552930221116651.
16. Sertcelik F, Akçay D, Livaoglu H, Gerdan S. The spectral decay parameter kappa in Marmara Region, Turkey. Arabian Journal of Geosciences 2022;15. doi:10.1007/s12517-021-09308-0.
17. Akyol N, Zhu L, Mitchell BJ, Sözbilir H, Kekovali K. Crustal structure and local seismicity in western Anatolia. Geophys J Int 2006;166:1259-1269. doi:10.1111/j.1365-246X.2006.03053.x.
18. Tezel T, Shibutani T, Kaypak B. Crustal structure variation in western Turkey inferred from the receiver function analysis. Tectonophysics 2010;492:240-252. doi:10.1016/j.tecto.2010.06.006.
19. Ozer C, Gok E, Polat O. Three-dimensional seismic velocity structure of the Aegean region of Turkey from local earthquake tomography. Annals of Geophysics 2018;61. doi:10.4401/ag-7543.
20. Mulumulu E, Özer Ç, Gök E, Chavez-Garcia FJ, Polat O. 3-D Upper crustal velocity structure of the Inner Gulf of Izmir from ambient noise tomography. Journal of the Faculty of Engineering and Architecture of Gazi University 2020;35:255-274. doi:10.17341/gazimmfd.460109.
21. Akyol N, Kurtulmuş TÖ, Çamyildiz M, Güngör T. Spectral ratio estimates for site effects on the horst-graben system in west Turkey. Pure Appl Geophys 2013;170:2107-2125. doi:10.1007/s00024-013-0661-2.
22. Demirci A, Bekler T. Büyük Menderes Grabeninde Cisim Dalgalarının Frekans Bağımlı Soğrulma Karakterinin Belirlenmesi. Doğal Afetler ve Çevre Dergisi 2019;5:116-123. doi:10.21324/dacd.449551.
23. Pamuk E, Özdağ ÖC, Akgün M. Soil characterization of Bornova Plain (Izmir, Turkey) and its surroundings using a combined survey of MASW and ReMi methods and Nakamura’s (HVSR) technique. Bulletin of Engineering Geology and the Environment 2019;78:3023-3035. doi:10.1007/s10064-018-1293-7.
24. Pamuk E, Özdağ ÖC, Tunçel A, Özyalın Ş, Akgün M. Local site effects evaluation for Aliağa/İzmir using HVSR (Nakamura technique) and MASW methods. Natural Hazards 2018;90:887-899. doi:10.1007/s11069-017-3077-y.
25. Cabas A, Rodriguez-Marek A, Bonilla LF. Estimation of site-specific Kappa (κ0)-consistent damping Values at KiK-Net sites to assess the discrepancy between laboratory-based damping models and observed attenuation (of seismic waves) in the field. Bulletin of the Seismological Society of America 2017;107:2258-2271. doi:10.1785/0120160370.
26. Ktenidou OJ, Abrahamson NA, Drouet S, Cotton F. Understanding the physics of kappa (κ): Insights from a downhole array. Geophys J Int 2015;203:678-691. doi:10.1093/gji/ggv315.
27. van Houtte C, Ktenidou OJ, Larkin T, Holden C. Hard-site κ0 (kappa) calculations for Christchurch, New Zealand, and comparison with local ground-motion prediction models. Bulletin of the Seismological Society of America 2014;104:1899-1913. doi:10.1785/0120130271.
28. Yılmaz Y, Gürer ÖF, Erbay AY. Batı Anadolu Grabenleri̇ni̇n Geli̇şi̇m Süreci İçi̇nde Selçuk Grabeni̇ni̇n Morfotektoni̇k Evri̇mi̇. Türkiye Jeoloji Bülteni / Geological Bulletin of Turkey 2023;66:275-324. doi:10.25288/tjb.1139766.
29. Jolivet L, Faccenna C, Huet B, Labrousse L, Le Pourhiet L, Lacombe O, et al. Aegean tectonics: Strain localisation, slab tearing and trench retreat. Tectonophysics 2013;597-598:1-33. doi:10.1016/j.tecto.2012.06.011.
30. Şengör AMC, Yazıcı M. The aetiology of the neotectonic evolution of Turkey. Mediterranean Geoscience Reviews 2020;2:327-339. doi:10.1007/s42990-020-00039-0.
31. Barbot S, Weiss JR. Connecting subduction, extension and shear localization across the Aegean Sea and Anatolia. Geophys J Int 2021;226:422-445. doi:10.1093/gji/ggab078.
32. Brun JP, Sokoutis D. Kinematics of the Southern Rhodope Core Complex (North Greece). International Journal of Earth Sciences 2007;96:1079-1099. doi:10.1007/s00531-007-0174-2.
33. Çiftçi NB, Temel RÖ, Iztan YH. Hydrocarbon occurrences in the western Anatolian (Aegean) grabens, Turkey: Is there a working petroleum system? Am Assoc Pet Geol Bull 2010;94:1827-1857. doi:10.1306/06301009172.
34. Sümer Ö, Sözbilir H, Uzel B. Büyük Menderes Granbeni’nin Rolling Hinge (Yuvarlanan Reze) Modelinde Supra-Detachment (Sıyrılma Üstü) Havzadan Rift Havzasına Evrimi. Türkiye Jeoloji Bülteni / Geological Bulletin of Turkey 2020;63:241-276. doi:10.25288/tjb.562552.
35. Bozkurt E, Mittwede SK. Introduction: Evolution of continental extensional tectonics of western Turkey. Geodinamica Acta 2005;18:153-165. doi:10.3166/ga.18.153-165.
36. Özkaptan M, Gülyüz E, Uzel B, Langereis CG, Özacar AA, Kaymakcı N. Deformation in SW Anatolia (Turkey) Documented by Anisotropy of Magnetic Susceptibility Data. Tectonics 2021;40:1-26. doi:10.1029/2021TC006882.
37. Duman TY, Çan T, Emre Ö, Kadirioğlu FT, Başarır Baştürk N, Kılıç T, et al. Seismotectonic database of Turkey. Bulletin of Earthquake Engineering 2018;16:3277-3316. doi:10.1007/s10518-016-9965-9.
38. Vamvakaris DA, Papazachos CB, Papaioannou CA, Scordilis EM, Karakaisis GF. A detailed seismic zonation model for shallow earthquakes in the broader Aegean area. Natural Hazards and Earth System Sciences 2016;16:55-84. doi:10.5194/nhess-16-55-2016.
39. Kiratzi A, Papazachos C, Özacar A, Pinar A, Kkallas C, Sopaci E. Characteristics of the 2020 Samos earthquake (Aegean Sea) using seismic data. Bulletin of Earthquake Engineering 2021;20:7713-7735. doi:10.1007/s10518-021-01239-1.
40. MTA. GeoScience Map Viewer. Maden Teknik ve Arama, Türkiye. Available from: http://yerbilimleri.mta.gov.tr/home.aspx [Accessed 26 April 2024].
41. AFAD. AFAD - TADAS. Türkiye İvme Ölçme Veri Tabanı ve Analiz Sistemi-TADAS. Available from: https://tadas.afad.gov.tr/map [Accessed 26 April 2024].
42. Sandıkkaya MA, Yılmaz MT, Bakır BS, Yılmaz Ö. Site classification of Turkish national strong-motion stations. J Seismol 2010;14:543-563. doi:10.1007/s10950-009-9182-y.
43. Kadirioğlu FT, Kartal RF. The new empirical magnitude conversion relations using an improved earthquake catalogue for Turkey and its near vicinity (1900-2012). Turkish Journal of Earth Sciences 2016;25:300-310. doi:10.3906/yer-1511-7.
44. Brune JN. Tectonic stress and the spectra of seismic shear waves from earthquakes. J Geophys Res 1970;75:4997-5009.
45. Douglas J, Gehl P, Bonilla LF, Gelis C. A κ model for mainland France. Pure Appl Geophys 2010;167:1303-1315. doi:10.1007/s00024-010-0146-5.
46. van Houtte C, Drouet S, Cotton F. Analysis of the origins of κ (kappa) to compute hard rock to rock adjustment factors for GMPEs. Bulletin of the Seismological Society of America 2011;101:2926-2941. doi:10.1785/0120100345.
47. Anderson JG. A preliminary descriptive model for the distance dependence of the spectral decay parameter in southern California. Bulletin of the Seismological Society of America 1991;81:2186-2193.
48. NEHRP. NEHRP Recommended Provisions for Seismic Regulations for New Buildings and Other Structures (FEMA 450). Part 1 2003:338.
49. Luzi L, Puglia R, Pacor F, Gallipoli MR, Bindi D, Mucciarelli M. Proposal for a soil classification based on parameters alternative or complementary to Vs,30. Bulletin of Earthquake Engineering 2011;9:1877-1898. doi:10.1007/s10518-011-9274-2.
50. Campbell KW. Estimates of shear-wave Q and κ0 for unconsolidated and semiconsolidated sediments in eastern north America. Bulletin of the Seismological Society of America 2009;99:2365-2392. doi:10.1785/0120080116.
51. Lee VW, Trifunac MD. Should average shear-wave velocity in the top 30m of soil be used to describe seismic amplification? Soil Dynamics and Earthquake Engineering 2010;30:1250-1258. doi:10.1016/j.soildyn.2010.05.007.