Onset of aseismic creep on major strike-slip faults

Time series analysis of spaceborne synthetic aperture radar (SAR) data, GPS measurements, and field observations reveal that the central section of the Izmit (Turkey) fault that slipped with a supershear rupture velocity in the A.D. 1999, M w 7.4, Izmit earthquake began creeping aseismically following the earthquake. Rapid initial postseismic afterslip decayed logarithmically with time and appears to have reached a steady rate comparable to the pre-earthquake full fault-crossing rate, suggesting that it may continue for decades and possibly until late in the earthquake cycle. If confirmed by future monitoring, these observations identify postseismic afterslip as a mechanism for initiating creep behavior along strike-slip faults. Long-term afterslip and/or creep has significant implications for earthquake cycle models, recurrence intervals of large earthquakes, and accordingly, seismic hazard estimation along mature strike-slip faults, in particular for Istanbul which is believed to lie adjacent to a seismic gap along the North Anatolian fault in the Sea of Marmara.

[1]  Robert M. Nadeau,et al.  Distribution of aseismic slip rate on the Hayward fault inferred from seismic and geodetic data , 2005 .

[2]  Ross D. Hartleb,et al.  The Surface Rupture and Slip Distribution of the 17 August 1999 İzmit Earthquake (M 7.4), North Anatolian Fault , 2002 .

[3]  James H. Dieterich,et al.  Progressive failure on the North Anatolian fault since 1939 by earthquake stress triggering , 1997 .

[4]  L. Warr,et al.  Nanocoatings of clay and creep of the San Andreas fault at Parkfield, California , 2010 .

[5]  C. Spiers,et al.  Fault rocks from the SAFOD core samples : implications for weakening at shallow depths along the San Andreas Fault, California , 2011 .

[6]  J. C. Savage,et al.  Geodetic determination of relative plate motion in central California , 1973 .

[7]  Y. Ben‐Zion,et al.  Temporal Changes of Shallow Seismic Velocity Around the Karadere-Düzce Branch of the North Anatolian Fault and Strong Ground Motion , 2006 .

[8]  Semih Ergintav,et al.  Izmit earthquake postseismic deformation and dynamics of the North Anatolian Fault Zone , 2009 .

[9]  Bertrand Meyer,et al.  Coseismic and early post-seismic slip associated with the 1999 Izmit earthquake (Turkey), from SAR interferometry and tectonic field observations , 2003 .

[10]  Semih Ergintav,et al.  Time-Dependent Distributed Afterslip on and Deep below the İzmit Earthquake Rupture , 2002 .

[11]  Andrew Hooper,et al.  A multi‐temporal InSAR method incorporating both persistent scatterer and small baseline approaches , 2008 .

[12]  R. Bürgmann,et al.  Earthquake potential along the northern hayward fault, california , 2000, Science.

[13]  Ares J. Rosakis,et al.  How fast is rupture during an earthquake? New insights from the 1999 Turkey Earthquakes , 2001 .

[14]  L. Warr,et al.  Clay mineral transformations and weakening mechanisms along the Alpine Fault, New Zealand , 2001, Geological Society, London, Special Publications.

[15]  Haluk Ozener,et al.  Seven years of postseismic deformation following the 1999, M = 7.4 and M = 7.2, Izmit-Düzce, Turkey earthquake sequence , 2009 .

[16]  Semih Ergintav,et al.  Creeping along the Ismetpasa section of the North Anatolian fault (Western Turkey): Rate and extent from InSAR , 2005 .

[17]  T. Herring,et al.  Introduction to GAMIT/GLOBK , 2006 .

[18]  James D. Byerlee,et al.  Friction, overpressure and fault normal compression , 1990 .

[19]  Tom Parsons,et al.  Recalculated probability of M >= 7 earthquakes beneath the Sea of Marmara, Turkey , 2004 .

[20]  C. Collettini,et al.  Fault zone fabric and fault weakness , 2009, Nature.

[21]  S. Hickman,et al.  Low strength of deep San Andreas fault gouge from SAFOD core , 2011, Nature.

[22]  Demitris Paradissis,et al.  GPS constraints on continental deformation in the Africa‐Arabia‐Eurasia continental collision zone and implications for the dynamics of plate interactions , 2005 .

[23]  Demian M. Saffer,et al.  Weakness of the San Andreas Fault revealed by samples from the active fault zone , 2011 .

[24]  Semih Ergintav,et al.  Afterslip and viscoelastic relaxation following the 1999 M 7.4 İzmit earthquake from GPS measurements , 2009 .