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It has long been observed that periods of intense seismic activity in a region alternate with periods of relative quiescence, but establishing whether or not this intermittency is driven by broad-scale physical processes occurring in the Earth, remains a challenge. Here, we address this question of long-range triggering by a large-scale analysis of evolution of the seismicity between 2003 and 2017 in the Anatolia region. Two multi-year periods of synchronous high seismicity rate in 27 seismicity clusters across the Anatolian plate are evidenced before a relatively uniform quiescence period. We argue that two remote tectonic processes are important for the timing of these activities: the 2004 M9.2 Sumatra earthquake and the 2008–2011 episode of slab rollback/deformation in the Hellenic subduction, even if a clear causal mechanism is still lacking. [ABSTRACT FROM AUTHOR]

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]