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Interseismic deformation and creeping along the central section of the North Anatolian fault (Turkey): InSAR observations and implications for rate-and-state friction properties

Yoshihiro Kaneko, Yuri Fialko, David T. Sandwell, & Xiaopeng Tong

Published 2013, SCEC Contribution #1657

We present high-resolution measurements of interseismic deformation along the central section of the North Anatolian fault (NAF) in Turkey using Interferometric Synthetic Aperture Radar (InSAR) data from ALOS and ENVISAT missions. We generated maps of satellite line-of-sight (LOS) velocity using five ascending ALOS tracks and one descending ENVISAT track covering the NAF between 31.2-34.3 degree East. The LOS velocity reveals discontinuities of up to $\sim$5 mm/year across the Ismetpasa segment of the NAF, implying surface creep at a rate of $\sim$9 mm/year; this is a large fraction of the inferred slip rate of the NAF (21-25 mm/year). The lateral extent of significant surface creep is about 75 km. We model the inferred surface velocity and shallow fault creep using numerical simulations of spontaneous earthquake sequences that incorporate laboratory-derived rate and state friction. Our results indicate that frictional behavior in the Ismetpasa segment is velocity strengthening at shallow depths and transitions to velocity weakening at a depth of 4-6 km. The inferred depth extent of shallow fault creep is 5.5-7 km, suggesting that the deeper locked portion of the partially creeping segment is characterized by a higher stressing rate, smaller events, and shorter recurrence interval. We also reproduce surface velocity in a locked segment of the NAF by fault models with velocity-weakening conditions at shallow depth. Our results imply that frictional behavior in a shallow portion of major active faults with little or no shallow creep is mostly velocity weakening.

Citation
Kaneko, Y., Fialko, Y., Sandwell, D. T., & Tong, X. (2013). Interseismic deformation and creeping along the central section of the North Anatolian fault (Turkey): InSAR observations and implications for rate-and-state friction properties. Journal of Geophysical Research, 118(1), 316-331. doi: 10.1029/2012JB009661.