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Estimation of shallow S-wave velocity structure and site response characteristics by microtremor array measurements in Tekirdag region, NW Turkey
© Karagoz et al. 2015
- Received: 26 March 2015
- Accepted: 29 August 2015
- Published: 4 November 2015
In this study, we aimed to explore the S-wave velocity structure of shallow soils using microtremors in order to estimate site responses in Tekirdag and surrounding areas (NW Turkey). We collected microtremor array data at 44 sites in Tekirdag, Marmara Ereglisi, Corlu, and Muratlı. The phase velocities of Rayleigh waves were estimated from the microtremor data using a Spatial Autocorrelation method. Then, we applied a hybrid genetic simulated annealing algorithm to obtain a 1D S-wave velocity structure at each site. Comparison between the horizontal-to-vertical ratio of microtremors and computed ellipticities of the fundamental mode Rayleigh waves showed good agreement with validation models. The depth of the engineering bedrock changed from 20 to 50 m in the Tekirdag city center and along the coastline with a velocity range of 700–930 m/s, and it ranged between 10 and 65 m in Marmara Ereglisi. The average S-wave velocity of the engineering bedrock was 780 m/s in the region. We obtained average S-wave velocities in the upper 30 m to compare site amplifications. Empirical relationships between the AVs30, the site amplifications, and also average topographic slopes were established for use in future site effects microzonation studies in the region.
- Microtremor array observation
- Phase velocity
- Shear-wave velocity
- Site amplification
Destructive earthquakes in the past have shown that local site conditions have major effects on ground shaking. S-wave velocity (Vs) structure is an important parameter in site amplification calculations for earthquake damages scenarios.
Estimation of Vs profiles with direct methods, like borehole and drilling, requires geophysical or laboratory testing and imposes significant cost and time constraints. However, there are simple, economical, and rapid indirect methods to evaluate Vs profiles, like spectral ratios of horizontal-to-vertical components (H/V) and microtremor array data analyses. Microtremor observations have become very popular because they are cost effective and rely on easily collected data for site characterization in terms of microzonation mapping (e.g., Kudo et al. 2002; Ozel et al. 2004; Zor et al. 2010; Grutas and Yamanaka 2012; Zaineh et al. 2012; Asten et al. 2014).
The importance of site effect studies has been more widely recognized since the 1999 Kocaeli Earthquake (Mw 7.4) in Marmara Region (NW Turkey), especially in the Istanbul megacity. There have been several site effect studies for Istanbul, Kocaeli, and Bursa cities. Although the Avcilar district of Istanbul in the western part of the city is ~150 km far from the Kocaeli earthquake epicenter, many buildings collapsed during the earthquake. This demonstrates that even places distance from an earthquake source cannot be considered safe. Ozel et al. (2002, 2004), Kudo et al. (2002), Ergin et al. (2004), Bozdag and Kocaoglu (2005), and Kılıç et al. (2006) studied site effects in western Istanbul (Avcilar, Yesilkoy, Bakirkoy, Zeytinburnu districts) using aftershock and microtremor records. They reported the existence of low S-wave velocities (~200 m/s) for shallow layers and high amplifications at low frequencies (<5 Hz). Site effects in the Kocaeli metropolitan area were also investigated in detail (Zor et al. 2010; Ozalaybey et al. 2011) and the 3D structure of the basin mapped. Gok and Polat (2012) studied site effects in Bursa city. However, there has been no comprehensive site effect study in the western side of the Marmara Region.
Our study area covers a rapidly growing part of Turkey and encompasses the main financial and industrial centers, including Istanbul which is one of the most populated cities in the world. In this study our target area was Tekirdag, the second largest province (150 km away from Istanbul) located on the north-western coastline of the Sea of Marmara with space available for future increases in urbanization and industrialization. Although Tekirdag is close to Istanbul, there have been no studies to define shallow velocity structures to the engineering bedrock for the city.
The main objective of this study was to explore the 1D Vs layer structures of shallow depths (0–100 m) from microtremor explorations in Tekirdag for future engineering applications. We investigated S-wave velocity profiles using phase velocities of Rayleigh waves and a hybrid inversion technique. Using the profiles, we discuss the site amplification in Tekirdag city and surrounding areas.
A detailed geology map of Tekirdag is given in Fig. 1b (Tekirdag Municipality, 2006). Tekirdag city is located on the southern part of the Thrace Basin. The study area is generally covered by Oligocene-Lower Miocene continental clastic rocks (siltstone, claystone, sandstone). There are also wide artificial landfill areas beneath the city center. The coastline between Tekirdag and Marmara Ereglisi consists of Middle-Upper Oligocene aged claystone, sandstone, and siltstone unites of the Danisment Formation (Fig. 1b). The elevation of topography increases from the coastline to the north as high as 200 m. The younger units are visible at higher elevations. There are also several N-S oriented creek beds filled with Quaternary soil. The alluvial bed of Cevizli Creek is the largest in the west of the city. Landfills were located in the city center of Tekirdag. The coastline is also covered with artificially filled areas to enlarge the main road and city park. The downtown of the city (around the site T04 in Fig. 1b) is covered by old city landfill on the claystone units.
Array measurements of microtremors
The microtremor measurement sites were deployed on different geological units as shown in Fig. 1b. T02, T08, T24, and T31 were located on claystone, T09, T23, T29, and T32 on the sandstone, and T21, T25, T03, T10, and T33 on the silt stone unit. We also had 3 sites (T04, T07, and T01) on the landfill, 4 sites on the clay-sand stone (T06, T11, T26, and T27) and 8 sites located on the alluvial units (T05, T20, T22, T13, T12, T28, T19, and T18).
There is no detailed geology map for the other three districts: Marmara Ereglisi, Muratlı, and Corlu. These areas consist of similar continental clastic rocks mainly in Miocene age according to information in the 1:500,000 large scaled geology map of Turkey from the General Directorate of Mineral Research and Exploration (MTA 2002) web page (Fig. 1b). This geological unit contains 14 sites (e.g., T14, T39, T44, T41). Muratlı and Corlu lie near the Ergene River which is one of the largest river in Thrace. We had only 7 sites in the northern part of the city.
The sites were deployed away from roads with high-traffic, factories, main bus stations, and other man-made temporary noise sources in order to record accurate data. We chose strong motion station locations of the Republic of Turkey Prime Ministry Disaster & Emergency Management Presidency (AFAD) Earthquake Department, schools, parks, governmental, or private lands for easy deployment of the circular arrays (Fig. 1b).
Station code, latitude, longitude, elevation, average slope, surface geology index (GI), array sizes of microtremor measurements, AVs30 values, and NEHRP site class
Small array side sizes (m)
NEHRP site class
Ave. Ampl (0.4–10 Hz)
Pre. freq (Hz)
Estimation of phase velocities
Phase velocities of Rayleigh waves were estimated from vertical components of microtremors using the SPAC method proposed by Okada (2003). The SPAC method computes cross-correlations between station pairs in the array with the SPAC coefficients for calculation of phase velocity at different frequencies. Each vertical-component record was divided into 81.92 s time segments. Then, the transient and artificial noises generated by local conditions such as pedestrians and cars near the sensors during the measurements were removed. The Parzen window with a band width of 0.2 Hz was chosen for smoothing in the data processing. We used the 6–14 segments (average 10) for averaging to get the phase velocity at each frequency. Further details on our data process can be found in previous studies (Grutas and Yamanaka 2012; Zaineh et al. 2012).
The three sites in group b in the area covered by landfill had phase velocities between 165 and 600 m/s. The frequency band was narrow (6–30 Hz). The dispersion curve of T04 was steep at high frequencies because the site was located on a hillside. The others were on the landfill along the coastline of Tekirdag city center (Fig. 1b).
Group c represents the phase velocities at the sites deployed on claystone. The phase velocities were between 230 and 700 m/s in frequency ranges larger than 5 Hz. T02, T08, and T31 had similar phase velocities at high frequency. T02 and T31 had the same velocities at low frequencies, while T08, located on the border of alluvium unit, had lower phase velocity. T24 had high velocities at all frequencies because it was located on a hill while the other sites in the group were located on a lowland area.
The sites measured on sandstone were designated group d. Their observed phase velocities ranged from 225 to 750 m/s at frequencies between 2.5 and 30 Hz. The three sites had consistent dispersion curves except T32. The T32 site showed a very high phase velocity (>500 m/s) at high frequencies.
The sites in groups e and f were deployed on Oligocene siltstone and Miocene clay-sandstone units, respectively. The dispersive features of both groups were similar, with phase velocities between 180 and 750 m/s on average. The geological unit of group f is younger than group e, with the former located in the northern part of the city center. T03 and T25, with higher velocities at high frequencies, were located at a high elevation (~150 m) with respect to the other sites in group e. In group f, T27 had a high phase velocity at high frequency like T25.
There were four and three observation sites in Muratli and Corlu towns, respectively, in group g. The phase velocities were between 210 and 630 m/s at frequencies between 3 and 30 Hz. Both towns are located in a flat area, and there is no significant elevation difference in Muratli. T44 was located at the highest elevation (~200 m) among the other sites in Corlu. It had a high velocity at a high frequency. On the other hand, the Corlu River, which built Quaternary alluvial beds, cuts both towns. The similar dispersion curves may reflect the similar geological and geomorphologic structures.
There were 6 sites in Marmara Ereglisi (group h). The observed phase velocities showed a wide variation from 160 to 850 m/s at frequencies between 4 and 30 Hz. Site T39 showed a very high velocity (650–900 m/s). The dispersion curve of T38 was very similar to those sites located on alluvial areas.
Inversion of phase velocities from dispersion curves
Example of search limits and optimal final models for the sites T22, T33, and T41
Final optimal model
Interpretation of the 1D S-wave velocity structure profiles
The Vs profiles of the sites in group a clearly indicate the variation in thickness of the alluvial sediments (Fig. 6a). The inversion results show that Cevizli Creek (west of Tekirdag city center) has much thick alluvial sediment (Vs = ~140 m/s) at its mouth (~30 m) with respect to up river parts (~20 m). The Agilovası Creek alluvial bed (east of the city center) had the lowest S-wave velocity (90 m/s) in the study area. The sites deployed on other alluvial creek beds showed similar velocities in the top layer (120–140 m/s). The S-wave velocities of the deepest parts beneath the thick sediments are low (350–600 m/s), while the sites on thin sediments have high velocities (~800 m/s) as engineering bedrock (T05, T12, T13, T18).
The uppermost layers of sites in groups b to f had an S-wave velocity between 200 and 400 m/s. These velocities represent the landfill, claystone, sandstone, and siltstone geological units observed on the surface. Distinctively, only one site (T32 in group d) deployed near the seaside had the highest S-wave velocity (~550 m/s) for its first layer. The S-wave velocity of the engineering bedrock was between 750 and 930 m/s. The engineering bedrock was not revealed at T08 and T11 in group c and f, respectively.
The Vs profiles in Corlu and Muratli (group g) were highly consistent, especially for shallow layers. The S-wave velocity of the first layers was 210 to 260 m/s. Only two sites (T42, T43) showed the engineering bedrock (~740 m/s) in this group.
The sites in group h in the town of Marmara Ereglisi are located along the coastline. The S-wave velocity of the top layer and the engineering bedrock were 200–370 m/s and 760–900 m/s, respectively. In addition, we estimated the deep structure velocities at two sites at 1050–1200 m/s (T16 and T39).
In general, the 1D Vs profiles indicate that the Tekirdag city center and coastal areas have different S-wave shallow structures. The top layers of the sites located on stiff soil had a velocity of ~200 m/s. On the contrary, consistent velocity values were observed in Marmara Ereglisi, Muratli, and Corlu towns. The engineering bedrock velocities ranged from 700 to 930 m/s. The sites in Marmara Ereglisi indicated the highest velocity for the deeper structure. On the other hand, the engineering bedrock beneath the sites in Corlu and Muratlı could not be revealed due to the thick upper soft soil layers in the Thrace Basin. The depth of the engineering bedrock is 20–50 m in Tekirdag city center and its eastern part and 10–65 m for Marmara Ereglisi.
The four-layer model according to average S-wave velocities from the inversion results in Tekirdag
Thickness range (m)
Average Vs (m/s)
The average shear-wave velocities of the layers were 210, 415, 600, and 780 m/s from the top to the bottom. The thicknesses of all layers changed from 2 to 55 m as tabulated in Table 3.
Horizontal-to-vertical spectral ratios
Generally the sites that had a thin first layer with low velocities exhibited a dominant peak at high frequencies (~10 Hz) due to high velocity contrast (i.e., T04, T21, T26). On the other hand, we observed peak values at low frequencies (~1–3 Hz) for much thicker first layers with low velocities (~150 m/s) (i.e., alluvial at T19, T22, T38). The sites with no significant velocity contrast between the layers had almost flat characteristics in the frequency range of 0.4–10 Hz (i.e., T24, T27, T32, and T39). The sites in Muratlı and Corlu town had similar flat characteristics at a frequency up to ~6 Hz (T40–2, T43).
The average AVs30 values along the AA’ profile are shown in Fig. 7. While the AVs30 values were higher in the west and the north (~530 m/s), they decreased in the city center. However, the AVs30 increased for sites to the east of T28. Low values were observed at sites having thick low velocity stiff soil layers (i.e., T11, T19, T29).
According to the National Earthquake Hazards Reduction Program (NEHRP) site classification (A-E), 2 sites are on soft soil (E), 11 sites on stiff soil (D), 28 sites on very dense soil/soft rock (C), and 1 site on rock (B) (Table 1). The sites in the northern part of the city center and the east part along the coastline are on soft rock (C). Marmara Ereglisi is also located on the soft rock except for T39 and T38 that are on rock (B) and stiff soil (D), respectively. The sites T01, T07, T12, and T13 close to the sea are on stiff soil (D). T20 and T28 were also located on the alluvial creek bed and are classified as stiff soil (D). However, at T02, T10, and T11 located in stone units, the AVs30 was around 310 m/s (stiff soil). Although the sites located near the seaside in Tekirdag showed low AVs30 values (E–D), we found high values (C–B) in Marmara Ereglisi (Fig. 13a). T38 had a similarly low value (240 m/s) at an alluvial site. The AVs30 velocities in Corlu (C) were higher than Muratlı (D). The only site in Muratli, T42, is on soft rock (490 m/s). It is located on the border between alluvial and continental clastic rocks and carbonates units.
1D site amplification factors
Site amplification factors were computed to understand the seismic motion behavior on the different geological units in the study area. Since we determined the depth to the engineering bedrock at 29 sites, we used a common half-space layer for each site as the engineering bedrock with an average Vs of ~780 m/s. We did not observed engineering bedrock beneath the other 13 sites. We used the average engineering bedrock depth of neighboring sites in the amplification calculations for those sites.
We used 1D wave propagation theory for vertically propagating S-waves to calculate site amplification. The amplification factor defines the ground motion on the surface to that of incident wave from the engineering bedrock. Because of lack of the quality factor information (Q) for Tekirdag and surroundings, it was assumed to be constant at 1/15 of Vs (Q = Vs/15) in this study (Iida et al. 2005).
The sites in class C were divided into two subgroups according to their AVs30 velocity ranges: C-1 for 450–650 m/s and C-2 for 350–450 m/s. Eleven sites in C-1 showed that the predominant frequencies ranged from 5 Hz to 15 Hz. The minimum amplification in the group was approximately 4, while the maximum amplification (~6.5) observed at T04 at a frequency of 13.5 Hz was similar at T27, both these sites being located on the youngest geological units. T14 had similar properties to T04 but the maximum frequency was 14.5 Hz, the same as T26. Although the predominant frequencies were similar (~5 Hz), amplification at T32 was half that at T33. The effect of the low velocity (~180 m/s) layer on the amplification at site T33 is clear.
C-2 contained 10 sites having dominant frequencies between 6 and 11 Hz. The minimum predominant frequency (~6 Hz) in the group was observed at site T15 located in the downtown of Marmara Ereglisi. T18 shows maximum amplification (~9) at 10 Hz due to a 2-m thin first layer and very low S-wave velocity (~90 m/s) of the alluvial material. We found that the predominant frequencies range for all sites in NEHRP class C were 5–15 Hz, and the amplification values were observed to be between 3 and 9.
The sites in class D according to their AVs30 values (250–350 m/s) showed predominant frequencies between 2 and 6 Hz. The most significant amplification was found at T20 located on the alluvial of Cevizli Creek, with a minimum frequency of 2.3 Hz and an amplification factor of 7. A thick sediment layer affects both the frequency and amplification properties at this site. T12 and T13 also showed the same amplification values at ~5 Hz as at T20.
T02 had very similar velocity structure to T04. Both sites were located in crowded urban areas and indicated the same amplification (~6.5) with different predominant frequencies. While T04 had a peak value at 13.5 Hz, T02 had a frequency of 3.5 Hz due to the much thicker (17 m) first layer. On the other hand, T01 has the same predominant frequency as T02. It is clear from the results that the thickness and velocity of the first layer significantly affect site amplification.
AVs30 and site amplification relationship
The alluvial units had higher amplification values than that of the other geological units. Sandstone sites designated as a soft rock (C) and rock sites (B) according to NEHRP showed the lowest amplification value with high AVs30 (T32 and T39) among the all site (Fig. 12).
AVs30 and slope relationship
The average S-wave velocity in the upper 30 m is one of the principle parameters for further studies such as microzonation, ground motion prediction equations (GMPEs) etc. (i.e., Stewart et al. 2012). Recent studies have shown good correlation between AVs30 and the slope of topography (e.g., Matsuoka et al. 2006; Allen and Wald 2007; Lemoine et al. 2012; Stewart et al. 2012).
The different geological units are also represented with different symbols according to the NEHRP site class range in Fig. 13b. The sites on alluvial areas indicated low slope and velocities. The landfill areas had much high slope values because they are in the city center that settled on the hills. The sites on the siltstone, sandstone, and claystone units were sparsely distributed. Continental clastic rocks that actually consist of silt/clay/sandstone units as mentioned before showed low average slope values because these units cover the flat areas of Corlu and Muratlı towns. The highest slope values were observed in Marmara Ereglisi. Unlike the other sites, T39 in Marmara Ereglisi had the highest velocity and slope value among the all sites.
Comparisons with the previous site effect studies in Marmara region
The site effect studies in Marmara Region indicated that high amplifications are observed at frequencies less than 4–5 Hz (i.e., Ozel et al. 2002). In particular, the Avcilar and Yesilkoy districts of the Istanbul metropolitan area have amplification between frequencies of 1 and 2 Hz (Ergin et al. 2004; Bozdag and Kocaoglu 2005). Picozzi et al. (2009) indicated that the southern coastline of the western part of Istanbul has fundamental frequencies as low as 0.1 Hz (i.e., Avcilar, Bakirkoy district) because of the thick sediments in the area. They found fundamental frequencies of 0.5–1 Hz for Atakoy and Zeytinburnu. On the other hand, Sørensen et al. (2006) obtained dominant peak amplifications (3–4) at around 1 Hz from microtremor H/V results at 30 sites in Atakoy and its surroundings.
Our results indicate that the dominant frequencies in the Tekirdag region were all higher than earlier results. Only two sites located on the alluvial creek bed showed maximum amplification at less than 2 Hz. Most of the sites located on claystone, sandstone, and siltstone units in Tekirdag had predominant frequencies higher than 2 Hz. The fundamental frequency range in Tekirdag was 1–10 Hz. However, the predominant frequency range was 1–16 Hz. As a result, Tekirdag and surrounding areas show better site responses with respect to the western part of Istanbul.
This study is the first comprehensive microtremor array measurements in Tekirdag city center and Marmara Ereglisi, Muratlı, and Corlu districts. The microtremor array measurements were performed at 44 sites to estimate S-wave velocity structures of the shallow soil layers in the study area. The observed Rayleigh wave phase velocities were between ~90 and 930 m/s in a frequency range from 2 to 30 Hz. We deduced the S-wave structures of the shallow soil in Tekirdag city center and coastal area. The top layers of sites located on the sandstone, claystone, and siltstone units had velocities of ~200 m/s. The velocities and thickness of the alluvial creek beds in coastal area were also clearly identified. The engineering bedrock velocities in the study area ranged from 700 to 930 m/s. The most significant part of the study area belongs to the alluvial creek beds. Our results indicate that the observed phase velocities change due to the thickness of alluvium. Additionally, we noticed that the shapes of the observed dispersion curves of alluvial units were similar.
The site amplifications, predominant frequencies, and site classifications according to the AVs30 values were determined to be input for future microzonation studies in Tekirdag and surroundings. According to the NHERP site classification, 28 sites are on dense soil/soft rock (class C) and 11 sites are on stiff soil (class D). We also proposed the relationship equations for AVs30-slope and AVs30-amplification for future use in site response prediction studies.
The authors would like to express deep gratitude to the Japan Ministry of Education, Culture, Sport, Science, and Technology (MEXT) for financial support, Science and Technology Research Partnership for Sustainable Development (SATREPS) for support for one of the authors’ PhD education at the Tokyo Institute of Technology. This study is part of the “Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey (MarDiM)” project, is also supported by Istanbul University (BAP Project no: 44524). The authors also would like to thank Dr. Hussam Eldein Zaineh’s help and contribution for this study. The author also would like to thank Assoc. Dr. Aysegul Askan (Middle East Technical University), MSc students Bengi Behiye Aksahin and Safa Arslan (Istanbul University), PhD student Fatma Nurten Sisman Dersan (Middle East Technical University), MSc Kaouro Kojima and MSc Tomohir Tsuchiya (Tokyo Institute of Technology) for their helps during the 2013-2014 field studies.
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- Allen TI, Wald DJ (2007) Topographic slope as a proxy for seismic site-conditions (VS30) and amplification around the globe. US Geol Surv 2007–1357:69, Open-File ReptGoogle Scholar
- Ambraseys NN, Finkel CF (1995) The seismicity of Turkey and adjacent areas—a historical review, 1500–1800. M. S. Eren Publications and Books, IstanbulGoogle Scholar
- Asten MW, Askan A, Ekincioglu EE, Sisman FN, Ugurhan B (2014) Site characterization in north-western Turkey based on SPAC and HVSR analysis of microtremor noise. Explor Geophys 45:74–85View ArticleGoogle Scholar
- Barka A (1992) The North Anatolian fault zone. Annales Tectonicae 6:164–195Google Scholar
- Bozdag E, Kocaoglu AH (2005) Estimation of site amplifications from shear-wave velocity profiles in Yesilyurt and Avcilar, Istanbul, by frequency-wavenumber analysis of microtremors. J Seismol 9:87–98View ArticleGoogle Scholar
- CEN (2004) Eurocode 8- design of structures for earthquake resistance. Part 1: general rules, seismic actions and rules for buildings. European standard EN 1998–1, December 2004. European Committee for Standardizitaion, BrusselsGoogle Scholar
- Ergin M, Ozalaybey S, Aktar M, Yalcın MN (2004) Site amplification at Avcılar, Istanbul. Tectonophysics 391:335–346View ArticleGoogle Scholar
- Gok E and Polat O (2012) Microtremor HVSR study of site effects in Bursa City (Northern Marmara Region, Turkey), earthquake research and analysis—new frontiers in seismology, Dr Sebastiano D’Amico (Ed.), ISBN: 978-953-307-840-3, InTech. http://cdn.intechopen.com/pdfs-wm/27143.pdf.
- Grutas R, Yamanaka H (2012) Shallow shear-wave velocity profiles and site response characteristics from microtremor array measurements in Metro Manila, the Philippines. Explor Geophys 43:255–266View ArticleGoogle Scholar
- Haskell NA (1953) The dispersion of surface waves on multilayered media. Bull Seism Soc Am 43:17–34Google Scholar
- Iida M, Yamanaka H, Yamada N (2005) Wave field estimated by borehole recordings in the reclaimed zone of Tokyo Bay. Bull Seismol Soc Am 95:1101–1119. doi:10.1785/0120040010 View ArticleGoogle Scholar
- Ketin I (1948) Über die tektonisch-mechanischen Folgerungen aus den großen Anatolischen Erdbeben des letzten Dezennium. Geol Rundschau 36:77–83View ArticleGoogle Scholar
- Kılıç H, Özener PT, Ansal A, Yıldırım M, Özaydın K, Adatepe Ş (2006) Microzonation of Zeytinburnu region with respect to soil amplification: a case study. Eng Geol 86:238–255View ArticleGoogle Scholar
- Kitsunezaki C, Goto N, Kobayashi Y, Ikawa T, Horike M, Saito T, Kurota T, Yamabe K, Okuzumi K (1990) Estimation of P- and S-wave velocities in deep soil deposits for evaluating ground vibrations in earthquake. J Japan Soc for Natural Disaster Scie 9:1–17Google Scholar
- Kudo K, Kanno T, Okada H, Ozel O, Erdik M, Sasatani T, Higashi S, Takahashi M, Yoshida (2002) Site specific issues for strong ground motions during the Kocaeli, Turkey earthquake of August 17, 1999, as inferred from array observations of microtremors and aftershocks. Bull Seism Soc Am 92:448–465. doi:10.1785/0120000812 View ArticleGoogle Scholar
- Lemoine A, Douglas J, Cotton F (2012) Testing the applicability of correlations between topographic slope and VS30 for Europe. Bull Seism Soc Am 102:2585–2599. doi:10.1785/0120110240 View ArticleGoogle Scholar
- Lomax A, Snieder R (1994) Finding sets of acceptable solutions with a genetic algorithm with application to surface wave group dispersion in Europe. Geophys Res Lett 21:2617–2620. doi:10.1029/ 94GL02635 View ArticleGoogle Scholar
- Matsuoka M, Wakamatsu K, Fujimoto K, Midorikawa S (2006) Average shear-wave velocity mapping using Japan engineering geomorphologic classification map. Structural Eng./Earthquake Eng. JSCE 23:57–68Google Scholar
- McClusky S, Balassanian S, Barka A, Demir A, Ergintav S, Georgiev I, Gurkan O, Hamburger M, Hurst K, Kahle H, Kastens K, Kekelidze G, King R, Kotzev V, Lenk O, Mahmoud S, Mishin A, Nadariya M, Ouzounis A, Paradissis D, Peter Y, Prilepin M, Reilinger R, Sanli I, Seeger H, Tealeb A, Toksöz MN, Veis G (2000) Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. J Geophys Res 105:5695–5719View ArticleGoogle Scholar
- MTA (2002) 1:500,000 Scale Geological Map. General Directorate of Mineral Research and Exploration (MTA), Eskisehir Yolu, 06520, Ankara, Turkey. http://www.mta.gov.tr/v2.0/daire-baskanliklari/jed/index.php?id=500bas (last visited 01.11.2015)
- Okada H (2003) The microtremor survey method. Geophysical Monograph series No.12, Society of Exploration Geophysicists, Tulsa.Google Scholar
- Okada H (2006) Theory of efficient array observations of microtremors with special reference to the SPAC method. Explor Geophys 37:73–85. doi:10.1071/EG06073 View ArticleGoogle Scholar
- Ozalaybey S, Zor E, Ergintav S, Tapırdamaz MC (2011) Investigation of 3-D basin structures in the Izmit Bay area (Turkey) by single-station microtremor and gravimetric methods. Geophys J Int 186:883–894View ArticleGoogle Scholar
- Ozel O, Cranswick E, Meremonte M, Erdik M, Safak E (2002) Site effects in Avcılar, West of Istanbul, Turkey from strong and weak motion data. Bull Seism Soc Am 92:499–508View ArticleGoogle Scholar
- Ozel O, Sasatani T, Kudo K, Okada H, Kanno T, Tsuno S, Yoshikawa M, Noguchi S, Miyahara M, Goto H (2004) Estimation of S-wave velocity structures in Avcilar-Istanbul from array microtremor measurements. Jour Fac Sci 12–2:115–129, Hokkaido Univ., SerVII (Geophysics)Google Scholar
- Picozzi M, Strollo A, Parolai S, Durukal E, Ozel O, Karabulut S, Zschau J, Erdik M (2009) Site characterization by seismic noise in Istanbul, Turkey. J of Soil Dyn and EarthqEng 29:469–482View ArticleGoogle Scholar
- Şengör AMC (1979) The North Anatolian transform fault: its age, offset and tectonic significance. J Geol Soc Lond 136:269–282View ArticleGoogle Scholar
- Sørensen M, Oprsal I, Bonnefoy-Claudet S, Atakan K, Martin Mai P, Pulido N, Yalcinar C (2006) Local site effects in Atakoy, Istanbul, Turkey, due to a future large earthquake in the Marmara Sea. Geophys J Int 167:1413–1424View ArticleGoogle Scholar
- Stewart J, Seyhan E, Boore DM, Campbell KW, Erdik M, Silva WJ, Di Alessandro C, Bozorgnia Y (2012) Site effects in parametric ground motion models for the GEM-PEER Global GMPEs Project. 15th World Conference on Earthquake Engineering (WCEE), 24-28 September 2012, Lisboa, Portugal.Google Scholar
- Tekirdag Municipality (2006) Geology Maps of Tekirdag (1:25.000 and 1:12.000 scales), Project for Investigation of Suitability for Settlement.Google Scholar
- Wessel P, Smith WHF (1998) New, improved version of the Generic Mapping Tools released. EOS Trans 47:579, AGU 79: noView ArticleGoogle Scholar
- Yamanaka H (2007) Inversion of surface-wave phase velocity using hybrid heuristic search method. Butsuri Tansa 60:265–275. doi:10.3124/segj.60.265 (in Japanese)View ArticleGoogle Scholar
- Yamanaka H, Ishida H (1996) Application of genetic algorithms to an inversion of surface-wave dispersion data. Bull Seism Soc Am 86:436–444Google Scholar
- Zaineh HE, Yamanaka H, Dakkak R, Khalil A, Daoud M (2012) Estimation of shallow S-Wave velocity structure in Damascus city Syria, using microtremor exploration. J of Soil Dyn and Earthq Eng 39:88–99View ArticleGoogle Scholar
- Zor E, Özalaybey S, Karaaslan A, Tapırdamaz MC, Özalaybey ÇS, Tarancıoğlu A, Erkan B (2010) Shear wave velocity structure of the İzmit Bay area (Turkey) estimated from active-passive array surface wave and single-station microtremor methods. Geophys J Int 182:1603–1618View ArticleGoogle Scholar