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| Titel |
Temporal variations of the fractal properties of seismicity in the western part of the north Anatolian fault zone: possible artifacts due to improvements in station coverage |
| VerfasserIn |
A. O. Öncel, Ö. Alptekin, I. Main |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 2, no. 3/4 ; Nr. 2, no. 3/4, S.147-157 |
| Datensatznummer |
250000250
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| Publikation (Nr.) |
 copernicus.org/npg-2-147-1995.pdf |
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| Zusammenfassung |
| Seismically-active fault zones are complex natural systems
exhibiting scale-invariant or fractal correlation between earthquakes in space and time,
and a power-law scaling of fault length or earthquake source dimension consistent with the
exponent b of the Gutenberg-Richter frequency-magnitude relation. The fractal dimension of
seismicity is a measure of the degree of both the heterogeneity of the process (whether
fixed or self-generated) and the clustering of seismic activity. Temporal variations of
the b-value and the two-point fractal (correlation) dimension Dc have been related to the
preparation process for natural earthquakes and rock fracture in the laboratory These
statistical scaling properties of seismicity may therefore have the potential at least to
be sensitive short- term predictors of major earthquakes. The North Anatolian Fault Zone
(NAFZ) is a seismicallyactive dextral strike slip fault zone which forms the northern
boundary of the westward moving Anatolian plate. It is splayed into three branches at
about 31oE and continues westward toward the northern Aegean sea. In this study, we
investigate the temporal variation of Dc and the Gutenberg-Richter b-value for seismicity
in the western part of the NAFZ (including the northern Aegean sea) for earthquakes of
Ms > 4.5 occurring in the period between 1900 and 1992. b ranges from 0.6-1.6 and Dc
from 0.6 to 1.4. The b-value is found to be weakly negatively correlated with Dc
(r=-0.56). However the (log of) event rate N is positively correlated with b, with a
similar degree of statistical significance (r=0.42), and negatively correlated with
Dc (r=-0.48). Since N increases dramatically with improved station coverage since 1970, the
observed negative correlation between b and Dc is therefore more likely to be due to this
effect than any underlying physical process in this case. We present this as an example of
how man-made artefacts of recording can have similar statistical effects to underlying
processes. |
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