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| Titel |
Seismotectonic setting at the North Anatolian Fault Zone after the 1999 Mw=7.4 Izmit earthquake based on high-resolution aftershock locations |
| VerfasserIn |
M. Bohnhoff, F. Bulut, E. Görgün, C. Milkereit, G. Dresen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7340
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| Digitales Dokument |
URL |
| Erschienen |
In: 2nd EGU Alexander von Humboldt Conference "The role of Geophysics in Natural Disaster Prevention" ; Nr. 14 (2008-01-02), S.85-92 |
| Datensatznummer |
250012087
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| Publikation (Nr.) |
 copernicus.org/adgeo-14-85-2008.pdf |
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| Zusammenfassung |
| The most recent devastating earthquakes that occurred along the North
Anatolian Fault Zone (NAFZ) in northwestern Turkey were the 1999 Izmit
(Mw=7.4) and Düzce (Mw=7.1) events. In this study we present a catalog
of Izmit aftershock hypocenters that was deduced from a network covering the
entire 140 km long rupture of the mainshock. 7348 events with a location
accuracy better than 5 km are analysed. Aftershocks were observed along the
entire ruptured segment along a 20 km wide band of activity. Events are
clustered in distinct regions and dominantly occur at 5 to 15 km depth. The
eastern termination of the Izmit rupture is characterized by a sharp and
steeply dipping boundary exactly where the Düzce mainshock initiated 87
days after the Izmit event. Relocation of the events using double-difference
technology results in 4696 high-resolution hypocenters that allow resolving
the internal structure of the seismically active areas with a resolution of
300 m (horizontal) and 400m (vertical). Below the Akyazi Plain, representing
a small pull-apart structure at a triple junction of the NAFZ, we identify
planes of activity that can be correlated with nodal planes of EW
extensional normal faulting aftershocks. Along the easternmost
Karadere-Düzce segment we identify the down-dip extension of the
Karadere fault that hosted about 1 m of right-lateral coseismic slip. At the
easternmost rupture we correlate a cloud-type distribution of seismic
activity with the largest aftershocks in this area, a subevent of the Izmit
mainshock and the Düzce mainshock that all have an almost identical
focal mechanism. This part of the NAFZ is interpreted as a classical example
of a seismic barrier along the fault. |
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