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Titel |
Attenuation Characteristics of the Armutlu Peninsula (NW Turkey) Using Coda Q |
VerfasserIn |
Evrim Yavuz, Deniz Çaka, Berna Tunç, Heiko Woith, Birger Gottfried Lühr, Şerif Baris |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250135234
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Publikation (Nr.) |
EGU/EGU2016-16074.pdf |
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Zusammenfassung |
Attenuation characteristic of seismic waves was determined using coda Q in the frame
of MARsite (MARsite has received funding from the European Union’s Seventh
Programme for research, technological development and demonstration under grant
agreement No 308417). Data from 82 earthquakes recorded in 2013-2014 in the
Armutlu Peninsula and its vicinity by 9 ARNET seismic stations were used for
processing. The earthquake magnitudes (Ml) and depths vary from 1.5 to 3.7 and
1.2-16.9 km, respectively. Epicentral distances closer than 90 km were selected to
ensure better signal-to-noise ratios. Lapse times between 20 seconds and 40 seconds
at intervals of 5 seconds were used for the calculation of the coda wave quality
factor. The coda windows were filtered at central frequencies of 1.5, 3, 6, 9 and 12
Hz bandpass filter. To obtain reliable results, only data with signal-to-noise ratios
greater than 5 and correlation coefficents higher than 0.7 were used. The SEISAN
software and one of its subroutines (CODAQ) were used for data processing and
analyses.
In the whole study area, Qc=(51±4)f^(0.91±0.04) for 20 seconds, Qc=(77±7)f^(0.80±0.04)
for 30 seconds and Qc=(112±13)f^(0.72±0.06) for 40 seconds lapse times are obtained for
coda wave quality factor. The observed quality factor is dependent on frequency and
lapse time. The results indicate that the upper lithosphere is more heterogeneous
and seismically more active than the lower lithosphere as expected in the region
which is tectonically complex refering to the effects of the North Anatolian Fault
Zone.
By considering earthquake clusters and recorded stations, the scattering area was drawn.
The intersection of the scattered areas for 20 seconds lapse time is covering all stations.
Quality factor in 1 Hz and frequency dependent values were calculated separately and for the
intersection of all scattered areas. Calculated Qo and n values of the intersection area are 50
and 0.89, respectively. Hence, the Qo and n values which are calculated using all stations and
both values of the intersection area are very close to each other. Additionally, in the
detailed review of TRML station which located in Yalova Province Termal District;
Qc=(46±3)f^(0.97±0.04) for 20 seconds, Qc=(61±6)f^(1.03±0.06), for 30 seconds and
Qc=(74±6)f^(1.06±0.05) for 40 seconds lapse times are obtained for coda wave
quality factor. With these results, both the lower Qo values increasing with lapse
times demonstrate high tectonic activity. Furthermore, the increasing n value with
lapse times is conformable with the geothermal sources, next to the TRML station. |
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