Thermal structure and megathrust seismogenic potential of the Makran subduction zone

The Makran subduction zone experienced a tsunamigenic Mw 8.1 earthquake in 1945 and recent, smaller earthquakes also suggest seismicity on the megathrust; however, its historical record is limited and hazard potential enigmatic. We have developed a 2-D thermal model of the subduction zone. The results are twofold: (1) The thick sediment cover on the incoming plate leads to high (~150°) plate boundary temperatures at the deformation front making the megathrust potentially seismogenic to a shallow depth, and (2) the shallow dip of the subducting plate leads to a wide potential seismogenic zone (up to ~350?km). Combining these results with along strike rupture scenarios indicates that Mw8.7–9.2 earthquakes are possible in the seaward Makran subduction zone. These results have important earthquake and tsunami hazard implications, particularly for the adjacent coastlines of Pakistan, Iran, Oman, and India, as the Makran has not been previously considered a likely candidate for a Mw?>?9 earthquake.

[1]  Robert S. White,et al.  Sediment compaction and fluid migration in the Makran Accretionary Prism , 1989 .

[2]  T. Minshull,et al.  Internal deformation and compaction of the Makran accretionary wedge , 1997 .

[3]  D. Lockner,et al.  Effects of smectite to illite transformation on the frictional strength and sliding stability of intact marine mudstones , 2012 .

[4]  L. Sykes,et al.  Loci and maximum size of thrust earthquakes and the mechanics of the shallow region of subduction zones , 1988 .

[5]  Richard G. Gordon,et al.  Geologically current plate motions , 2010 .

[6]  Walter H. F. Smith,et al.  Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings , 1997 .

[7]  R. Whitmarsh.  The Owen Basin off the south‐east margin of Arabia and the evolution of the Owen Fracture Zone , 1979 .

[8]  M. Yamano,et al.  The seismogenic zone of subduction thrust faults , 1997 .

[9]  R. Hyndman,et al.  The thermal structure of subduction zone back arcs , 2004 .

[10]  Simon M. Peacock,et al.  Hydrous minerals in the mantle wedge and the maximum depth of subduction thrust earthquakes , 1999 .

[11]  Costas E. Synolakis,et al.  Far-field tsunami hazard from mega-thrust earthquakes in the Indian Ocean , 2008 .

[12]  M. Gutscher,et al.  Great Earthquakes in Slow-Subduction, Low-Taper Margins , 2009 .

[13]  Simon M. Peacock,et al.  Serpentinization of the forearc mantle , 2003 .

[14]  E. Engdahl,et al.  Global teleseismic earthquake relocation with improved travel times and procedures for depth determination , 1998, Bulletin of the Seismological Society of America.

[15]  Kelin Wang,et al.  Thermal constraints on the seismogenic portion of the southwestern Japan subduction thrust , 1995 .

[16]  Jonathan M. Bull,et al.  The structure and fault activity of the Makran accretionary prism , 2012 .

[17]  Kelin Wang,et al.  Coseismic strengthening of the shallow portion of the subduction fault and its effects on wedge taper , 2008 .

[18]  H. Kanamori,et al.  A moment magnitude scale , 1979 .

[19]  M. Gutscher,et al.  Thermal models of flat subduction and the rupture zone of great subduction earthquakes , 2001 .

[20]  Kelin Wang,et al.  Accretionary prisms in subduction earthquake cycles: The theory of dynamic Coulomb wedge , 2006 .

[21]  Moharram D. Pirooz,et al.  Modeling the near-field effects of the worst-case tsunami in the Makran subduction zone , 2009 .

[22]  Kelin Wang,et al.  Thermal effects of marine sedimentation in hydrothermally active areas , 1992 .

[23]  A. Rosenberger,et al.  Comparison of measured and BSR-derived heat flow values, Makran accretionary prism, Pakistan , 2000 .

[24]  G. Jacoby,et al.  Tree-ring evidence for an A.D. 1700 Cascadia earthquake in Washington and northern Oregon , 1997 .

[25]  H. Permana,et al.  Updip rupture of the 2004 Sumatra earthquake extended by thick indurated sediments , 2011 .

[26]  S. Stein,et al.  A model for the global variation in oceanic depth and heat flow with lithospheric age , 1992, Nature.

[27]  Kelin Wang,et al.  The updip and downdip limits to great subduction earthquakes: Thermal and structural models of Casca , 1999 .

[28]  Kelin Wang,et al.  Thermal constraints on the zone of major thrust earthquake failure: The Cascadia Subduction Zone , 1993 .

[29]  Kelin Wang,et al.  Common depth of slab‐mantle decoupling: Reconciling diversity and uniformity of subduction zones , 2009 .

[30]  Kelin Wang,et al.  Case for very low coupling stress on the Cascadia Ssubduction Fault , 1995 .

[31]  M. Gutscher,et al.  Limits of the seismogenic zone in the epicentral region of the 26 December 2004 great Sumatra-Andaman earthquake: Results from seismic refraction and wide-angle reflection surveys and thermal modeling , 2010, 1002.1548.

[32]  Kelin Wang,et al.  Do subducting seamounts generate or stop large earthquakes , 2011 .

[33]  Chen Ji,et al.  Coseismic Slip and Afterslip of the Great Mw 9.15 Sumatra–Andaman Earthquake of 2004 , 2007 .

[34]  Harmen Bijwaard,et al.  Closing the gap between regional and global travel time tomography , 1998 .

[35]  Daniel M. Davis,et al.  GREAT THRUST EARTHQUAKES AND ASEISMIC SLIP ALONG THE PLATE BOUNDARY OF THE MAKRAN SUBDUCTION ZONE , 1992 .

[36]  Moharram D. Pirooz,et al.  Historical tsunami in the Makran Subduction Zone off the southern coasts of Iran and Pakistan and results of numerical modeling , 2008 .

[37]  W. Prell,et al.  A multiphase plate tectonic history of the southeast continental margin of Oman , 1990, Geological Society, London, Special Publications.

[38]  R. White,et al.  Heat flow and age of the Gulf of Oman , 1981 .

[39]  Narumi Takahashi,et al.  The 2011 Tohoku-Oki Earthquake: Displacement Reaching the Trench Axis , 2011, Science.