Separation of Source, Propagation and Site Effects from S Waves¶of Local Earthquakes in Bursa Region, Northwestern Turkey

Akyol, Nihal; Akinci, Aybige; Eyidoǧan, Haluk

doi:10.1007/s00024-002-8680-4

Cited by 14 publications

(5 citation statements)

References 6 publications

(8 reference statements)

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“…Among the earlier studies on the neighboring areas of Turkey, Eck [1988] at 25 s were calculated by Rahimi and Hamzehloo [2008]; the average frequency relation for Central Iran was determined as Q c =(79±2)f (1.07±0.08) by Rahimi et al [2010]; a regional Q c =126f 1.05 relation was approximated by Meirova and Pinsky [2004] based on S wave coda decay rate for Israel. The discrepancies between the present results and those ones obtained in previous studies of Marmara Region reported in "Introduction" section and in Table 6 might be due to the differences in the considered window lengths and kind of quality factor vary from one author to another [Barış et al, 1992;Horasan et al, 1998;Kaşlılar-Özcan, 1999;Akyol et al, 2002;Horasan and Boztepe-Güney, 2004;Sertcelik and Guleroglu, 2017]. Generally, most of the studies demonstrate <200 of Q values and this suggest an active tectonic settings.…”

Section: Resultscontrasting

confidence: 82%

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Yavuz

Barış²

2019

Annals of Geophysics

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The Armutlu Peninsula, is located in a geologically complex system on the North Anatolian Fault Zone and inside the high populated Marmara Region. Due to its location and importance, the Marmara Region has been subject to various studies in the past; now, this study is aimed to determine the local attenuation characteristic of the Armutlu Peninsula. In this study, 75 earthquake data that were recorded between 2013-2014, were analyzed by 9 seismic stations. The magnitudes (Ml) and the focal depths of the earthquakes vary from 1.5 to 3.3 and 0.9 to 16.9 km, respectively. A single back-scattering model was used for calculation of the coda wave quality factor. The lapse times were determined between 20 and 40 s at intervals of 5 s and they were filtered at central frequencies of 1.5, 3, 6, 9 and 12 Hz band-pass designed filter. Minimum 5 signal/noise ratio and 0.7 correlation coefficient data used to obtain reliable results. The CODAQ subroutine integrated in the SEISAN software was used for data processing. For each station, low values of the quality factor at 1 Hz (Q o ) and high values of the frequency dependent parameter (n) were determined. In the Armutlu Peninsula and its surroundings, Q c =51f 0.91 for 20 s and Q c =112f 0.72 for 40 s window lengths were calculated by using 9 stations. There is a tendency between increasing Q o and decreasing n parameters. Otherwise, for station TRML, located near the geothermal hotspot, these parameters are in direct proportion with each other, as Q c =46f 0.97 for 20 s and Q c =74f 1.06 for 40 s window lengths. These parameter changes are directly connected with the geothermal activity. the rate of coda wave attenuation [Aki, 1969]. Local/regional recorded coda waves (up to 100 km epicentral distance) and their power spectra as well as coda duration are relatively independent from the focal distance [Aki and Chouet, 1975]. Q c determination studies are generally performed in tectonically active fields, active volcanic regions, earthquake swarm areas, magmatic flows and geothermal areas [

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Section: Resultscontrasting

confidence: 82%

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Yavuz

Barış²

2019

Annals of Geophysics

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“…There are many studies that focus on modeling and mitigation, especially earthquake risk of the city of Bursa (Öncü 2021;Taş 2003). A number of studies deal with local site effect problems, since the city of Bursa is located in a deep alluvial basin (Akyol et al, 2002a;2002b;Topal et al, 2003 Subaşı et al 2019). The effect of soil ampli cation in Bursa was also observed in far-eld earthquakes (Ansal et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The Importance of Seismic Microzonation under the Threat of an Earthquake of the North Anatolian Fault in Nilüfer, Bursa, Turkey

Bıçakcı,

Özçep,

Karabulut

et al. 2023

Preprint

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The district of Nilüfer experienced the most recent urbanization among the central districts of Bursa in South Marmara with completion of rapid construction. Since 358 BC, there were many destructive earthquakes on the branches of the North Anatolian Fault reported which caused great damage in the city of Bursa and cost many lives. Besides some studies conducted to define the soil behaviour in the vicinity of Bursa, the seismic hazard of Nilüfer and the surrounding region remains a problem. In this study, an earthquake hazard analysis was first conducted and the peak ground acceleration (PGA) values were determined with respect to an expected earthquake. In the next step, MASW (Multi-Channel Analysis of Surfave Wave) measurements were conducted at 54 points in 28 neighborhoods of Nilüfer district. Soil mechanical parameters were determined at 11 boroholes, which were calculated as the probability of liquefaction. It was found that almost half of the study area suffers from low damage considering only the vulnerability index (Kg) index, which depends on the site effect. Therefore, in addition to the Kg values, we created a microzonation map using the results by soil liquefaction, settlement, changes of ground water level and the average values of spectral acceleration. The results showed four different areas with low to high damage. Altınşehir, Hippodrome, Ürünlü and Alaaddinbey, Ertuğrul, 29 Ekim, 23 Nisan, Ahmetyesevi and Minareliçavuş districts also have high risk of damage levels that could not be quantified by Kg index alone. The results of this study clearly show that considering the Kg index, which depends only on the local site effect, may lead to inadequate damage values.

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“…Boreholes undertaken by the General Directorate of State Hydraulic Works of Turkey (DSI) and private companies indicate that the thickness of unconsolidated materials underlying the basin ranges from 100 to 300 m (ULUSAY et al, 2000). There are many basins in Turkey which have similar characteristics with Cukurova, such as the Bursa, Dinar and Erzincan basins (AKYOL et al, 2002;YALCINKAYA and ALPTEKIN, 2003), and most of these basins are located in the first degree earthquake regions according to the Seismic Zoning Map of Turkey. Knowledge of the site response in these basins is important to mitigate the seismic risk.…”

Section: Introductionmentioning

confidence: 99%

Site Effect and its Relationship to the Intensity and Damage Observed in the June 27, 1998 Adana-Ceyhan Earthquake

Yalçınkaya

Alptekin

2005

Pure appl. geophys.

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The site response at 15 stations in the Adana-Ceyhan region (Southern Turkey) is calculated from the recordings of aftershocks of June 27, 1998 Adana-Ceyhan earthquake (M S ¼ 6.2) by using the Standard Spectral Ratio (SSR) and the Horizontal-to-Vertical Spectral Ratio (HVSR) methods. While the two methods are in good harmony at a few stations in determining the site effects, they show differences on the estimated amplifications or on the site resonance frequencies at most stations. It was not clear which one of the two methods underestimates or overestimates the amplification values. We observe that at some stations, where the local site conditions are rather complex, the vertical component records are strongly influenced from the local soil conditions. Thus, the HVSR method fails at these stations. The SSR method underestimates the amplifications at some stations since the rock site, selected as reference site, has its own site response and/or the path correction we applied, considering the geometrical spreading factor only, is insufficient. At the sites where high intensity values were observed, we found high amplifications. The fundamental soil frequencies characterize the damage properties observed in the Adana-Ceyhan earthquake. The fundamental soil frequency is nearly at 1.1 Hz at the Ceyhan site, where severe damage was observed in the 5-6 story buildings, while the fundamental soil frequency is between 3-6 Hz at the Adana site, where damage was in the low-story buildings. Therefore, in addition to inefficient construction practices, it is clear that the resonance effects have also contributed to the observed damage.

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Separation of Source, Propagation and Site Effects from S Waves¶of Local Earthquakes in Bursa Region, Northwestern Turkey

Cited by 14 publications

References 6 publications

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

Determination of Coda Wave Attenuation Characteristic of the Armutlu Peninsula and Its Surroundings (Middle Marmara Region, Turkey).

The Importance of Seismic Microzonation under the Threat of an Earthquake of the North Anatolian Fault in Nilüfer, Bursa, Turkey

Site Effect and its Relationship to the Intensity and Damage Observed in the June 27, 1998 Adana-Ceyhan Earthquake

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