Extended Nucleation of the 1999 M w 7.6 Izmit Earthquake

Laboratory and theoretical studies suggest that earthquakes are preceded by a phase of developing slip instability in which the fault slips slowly before accelerating to dynamic rupture. We report here that one of the best-recorded large earthquakes to date, the 1999 moment magnitude (M w ) 7.6 Izmi...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2011-02, Vol.331 (6019), p.877-880
Main Authors: Bouchon, Michel, Karabulut, Hayrullah, Aktar, Mustafa, Özalaybey, Serdar, Schmittbuhl, Jean, Bouin, Marie-Paule
Format: Article
Language:English
Subjects:
Amplitude
Earthquakes
Nucleation
Observational research
Research facilities
S waves
Scientific observation
Signal noise
Travel time
Waveforms
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Summary:Laboratory and theoretical studies suggest that earthquakes are preceded by a phase of developing slip instability in which the fault slips slowly before accelerating to dynamic rupture. We report here that one of the best-recorded large earthquakes to date, the 1999 moment magnitude (M w ) 7.6 Izmit (Turkey) earthquake, was preceded by a seismic signal of long duration that originated from the hypocenter. The signal consisted of a succession of repetitive seismic bursts, accelerating with time, and increased low-frequency seismic noise. These observations show that the earthquake was preceded for 44 minutes by a phase of slow slip occurring at the base of the brittle crust. This slip accelerated slowly initially, and then rapidly accelerated in the 2 minutes preceding the earthquake.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1197341