Separating rapid relocking, afterslip, and viscoelastic relaxation: An application of the postseismic straightening method to the Maule 2010 cGPS

The postseismic deformation captured with continuous Global Positioning System (cGPS) monitoring following many recent mega-thrust events has been shown to be a signal composed of two dominant processes: afterslip on the plate interface and viscoelastic relaxation of the continental and oceanic mantles in response to the coseismic stress perturbation. Following the south-central Chile 2010 Maule Mw 8.8 earthquake, the time series from the regional cGPS network show a distinct curvature in the pathway of the horizontal motion that is not easily fit by a stationary decaying pattern of afterslip in combination with viscoelastic relaxation. Here we show that with realistic assumptions about the long-term decay of the afterslip signal, the postseismic signal can be decomposed into three first-order contributing processes: plate interface re-locking, plate interface afterslip, and mantle viscoelastic relaxation. From our analyses we conclude that the plate interface recovers its interseismic locking state rapidly (model space ranges between an instant recovery and a period of 1 year); a finding that supports laboratory experimental evidence as well as some recent studies of aftershocks and postseismic surface deformation. Furthermore, re-locking is the main cause of the curvature in the cGPS signal, and this study presents a plausible range of geodetic re-locking rates following a megathrust earthquake.

[1]  R. Madariaga,et al.  The 2010 Mw 8.8 Maule Megathrust Earthquake of Central Chile, Monitored by GPS , 2011, Science.

[2]  Anthony Sladen,et al.  Seismic and aseismic slip on the Central Peru megathrust , 2010, Nature.

[3]  Kelin Wang,et al.  Three-dimensional viscoelastic finite element model for postseismic deformation of the great 1960 Chile earthquake , 2004 .

[4]  Z. Altamimi,et al.  ITRF2008: an improved solution of the international terrestrial reference frame , 2011 .

[5]  Ian Parsons,et al.  Surface deformation due to shear and tensile faults in a half-space , 1986 .

[6]  Michael Bevis,et al.  Toward understanding tectonic control on the Mw 8.8 2010 Maule Chile earthquake , 2012 .

[7]  Acceleration of regional plate subduction beneath Kanto, Japan, after the 2011 Tohoku‐oki earthquake , 2016 .

[8]  M. Kido,et al.  Potential tsunamigenic faults of the 2011 off the Pacific coast of Tohoku Earthquake , 2011 .

[9]  Michael Bevis,et al.  A high-resolution, time-variable afterslip model for the 2010 Maule Mw = 8.8, Chile megathrust earthquake , 2013 .

[10]  M. Moreno,et al.  Contrasting amount of fluids along the megathrust ruptured by the 2010 Maule earthquake as revealed by a combined analysis of aftershocks and afterslip , 2016 .

[11]  Timothy H. Dixon,et al.  REVEL: A model for Recent plate velocities from space geodesy , 2002 .

[12]  S. Constable,et al.  Melt-rich channel observed at the lithosphere–asthenosphere boundary , 2013, Nature.

[13]  A. Echaurren,et al.  Anatomy of the Andean subduction zone: three-dimensional density model upgraded and compared against global-scale models , 2012 .

[14]  R. Madariaga,et al.  The Constitución earthquake of 25 March 2012: A large aftershock of the Maule earthquake near the bottom of the seismogenic zone , 2013 .

[15]  E. Klein,et al.  Afterslip and viscoelastic relaxation model inferred from the large-scale post-seismic deformation following the 2010 Mw 8.8 Maule earthquake (Chile) , 2015 .

[16]  G. Hayes,et al.  Seismotectonic framework of the 2010 February 27 Mw 8.8 Maule, Chile earthquake sequence , 2013 .

[17]  Frederik Tilmann,et al.  The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake? , 2016 .

[18]  H. Schuh,et al.  Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium‐Range Weather Forecasts operational analysis data , 2006 .

[19]  M. Bevis,et al.  Heterogeneous plate locking in the South–Central Chile subduction zone: Building up the next great earthquake , 2011 .

[20]  Brendan J. Meade,et al.  Geodetic imaging of coseismic slip and postseismic afterslip: Sparsity promoting methods applied to the great Tohoku earthquake , 2012 .

[21]  Makoto Murakami,et al.  Coseismic and postseismic crustal deformation after the Mw 8 Tokachi-oki earthquake in Japan , 2004 .

[22]  D. Lange,et al.  Comparison of postseismic afterslip models with aftershock seismicity for three subduction-zone earthquakes: Nias 2005, Maule 2010 and Tohoku 2011 , 2014 .

[23]  K. Heki,et al.  Accelerated Pacific Plate Subduction Following Interplate Thrust Earthquakes at the Japan Trench , 2013 .

[24]  S. Wiemer,et al.  Randomness of megathrust earthquakes implied by rapid stress recovery after the Japan earthquake , 2015 .

[25]  Kelin Wang,et al.  Deformation cycles of subduction earthquakes in a viscoelastic Earth , 2012, Nature.

[26]  F. Cotton,et al.  Spatial and temporal evolution of a long term slow slip event: the 2006 Guerrero Slow Slip Event , 2011 .

[27]  M. Simons,et al.  An elastic plate model for interseismic deformation in subduction zones , 2010 .

[28]  J. Mitrovica,et al.  Haskell [1935] revisited , 1996 .

[29]  S. Cox,et al.  Evolution of strength recovery and permeability during fluid–rock reaction in experimental fault zones , 2002 .

[30]  Sarah E. Minson,et al.  The 2011 Magnitude 9.0 Tohoku-Oki Earthquake: Mosaicking the Megathrust from Seconds to Centuries , 2011, Science.

[31]  M. Moreno,et al.  2010 Maule earthquake slip correlates with pre-seismic locking of Andean subduction zone , 2010, Nature.

[32]  J. Avouac,et al.  Modeling afterslip and aftershocks following the 1992 Landers earthquake , 2007 .

[33]  V. E. Levin,et al.  Rapid aseismic moment release following the 5 December, 1997 Kronotsky, Kamchatka, Earthquake , 2001 .

[34]  Yehuda Bock,et al.  Physical applications of GPS geodesy: a review , 2016, Reports on progress in physics. Physical Society.

[35]  M. Moreno,et al.  Revisiting viscoelastic effects on interseismic deformation and locking degree: A case study of the Peru‐North Chile subduction zone , 2015 .

[36]  Chris Rizos,et al.  The International GNSS Service in a changing landscape of Global Navigation Satellite Systems , 2009 .

[37]  Kelin Wang,et al.  Spherical‐Earth finite element model of short‐term postseismic deformation following the 2004 Sumatra earthquake , 2012 .

[38]  F. Pollitz,et al.  Seismic versus aseismic slip: Probing mechanical properties of the northeast Japan subduction zone , 2014 .

[39]  Timothy Masterlark,et al.  Strong interseismic coupling, fault afterslip, and viscoelastic flow before and after the Oct. 9, 1995 Colima‐Jalisco earthquake: Continuous GPS measurements from Colima, Mexico , 2002 .

[40]  Motoyuki Kido,et al.  Prevalence of viscoelastic relaxation after the 2011 Tohoku-oki earthquake , 2014, Nature.

[41]  J. C. Savage.  A dislocation model of strain accumulation and release at a subduction zone , 1983 .

[42]  J. Nocquet,et al.  Slip distribution of the February 27, 2010 Mw = 8.8 Maule Earthquake, central Chile, from static and high‐rate GPS, InSAR, and broadband teleseismic data , 2010 .

[43]  Matthew G. Knepley,et al.  A domain decomposition approach to implementing fault slip in finite‐element models of quasi‐static and dynamic crustal deformation , 2013, ArXiv.

[44]  Michael Bevis,et al.  Trajectory models and reference frames for crustal motion geodesy , 2014, Journal of Geodesy.

[45]  J. Jackson,et al.  Tsunami earthquake generation by the release of gravitational potential energy , 2012 .

[46]  Kelin Wang,et al.  Viscoelastic relaxation following subduction earthquakes and its effects on afterslip determination , 2015 .

[47]  Georg Dresen,et al.  Rheology of the Lower Crust and Upper Mantle: Evidence from Rock Mechanics, Geodesy, and Field Observations , 2008 .

[48]  J. Vidale,et al.  Seismic Evidence for Rock Damage and Healing on the San Andreas Fault Associated with the 2004 M 6.0 Parkfield Earthquake , 2005 .

[49]  The 2010 Mw 8.8 Maule, Chile earthquake: Nucleation and rupture propagation controlled by a subducted topographic high , 2012 .

[50]  T. Shimamoto,et al.  Rapid postseismic strength recovery of Pingxi fault gouge from the Longmenshan fault system: Experiments and implications for the mechanisms of high‐velocity weakening of faults , 2013 .

[51]  Magali I. Billen,et al.  A low viscosity wedge in subduction zones , 2001 .

[52]  J. Avouac,et al.  Postseismic relocking of the subduction megathrust following the 2007 Pisco, Peru, earthquake , 2016 .

[53]  Hiromichi Tsuji,et al.  Silent fault slip following an interplate thrust earthquake at the Japan Trench , 1997, Nature.

[54]  Thomas R. Walter,et al.  Overlapping post-seismic deformation processes: afterslip and viscoelastic relaxation following the 2011 Mw 9.0 Tohoku (Japan) earthquake , 2014 .

[55]  R. Bürgmann,et al.  Stress-dependent power-law flow in the upper mantle following the 2002 Denali, Alaska, earthquake , 2006 .