Extended Nucleation of the 1999 Mw 7.6 Izmit Earthquake

Michel Bouchon (1) , Hayrullah Karabulut (2) , Mustafa Aktar (2) , Serdar Özalaybey (3) , Jean Schmittbuhl (4) , Marie-Paule Bouin (5)

1 Mécanique des failles
2 KOERI - Kandilli Observatory and Earthquake Research Institute
3 Earth and Marine Sciences Research Institute [Gebze]
4 IPGS-Sismologie - Sismologie (IPGS)
5 Observatoire Volcanologique de Guadeloupe

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 (Mw) 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. [ABSTRACT FROM AUTHOR]

Mots clés: Nucleation; seismology; geology; faults; Izmit; Turkey

Domaines: Géomorphologie

Michel Bouchon, Hayrullah Karabulut, Mustafa Aktar, Serdar Özalaybey, Jean Schmittbuhl, et al.. Extended Nucleation of the 1999 Mw 7.6 Izmit Earthquake. Science, 2011, 331 (6019), pp.877-880. ⟨10.1126/science.1197341⟩. ⟨insu-00679411⟩