Slow slip source characterized by lithological and geometric heterogeneity

Slow slip events on subduction megathrusts are linked to subduction of rough crust and heterogeneous fault rock properties. Slow slip events (SSEs) accommodate a significant proportion of tectonic plate motion at subduction zones, yet little is known about the faults that actually host them. The shallow depth (<2 km) of well-documented SSEs at the Hikurangi subduction zone offshore New Zealand offers a unique opportunity to link geophysical imaging of the subduction zone with direct access to incoming material that represents the megathrust fault rocks hosting slow slip. Two recent International Ocean Discovery Program Expeditions sampled this incoming material before it is entrained immediately down-dip along the shallow plate interface. Drilling results, tied to regional seismic reflection images, reveal heterogeneous lithologies with highly variable physical properties entering the SSE source region. These observations suggest that SSEs and associated slow earthquake phenomena are promoted by lithological, mechanical, and frictional heterogeneity within the fault zone, enhanced by geometric complexity associated with subduction of rough crust.

[1]  J. Morgan,et al.  Imaging the Shallow Subsurface Structure of the North Hikurangi Subduction Zone, New Zealand, Using 2‐D Full‐Waveform Inversion , 2019, Journal of Geophysical Research: Solid Earth.

[2]  S. Lebedev,et al.  Episodic stress and fluid pressure cycling in subducting oceanic crust during slow slip , 2019, Nature Geoscience.

[3]  L. Wallace,et al.  Hikurangi Subduction Margin Coring, Logging, and Observatories , 2019, Proceedings of the International Ocean Discovery Program.

[4]  A. Niemeijer,et al.  Temperature-dependent frictional properties of heterogeneous Hikurangi Subduction Zone input sediments, ODP Site 1124 , 2019, Tectonophysics.

[5]  L. Wallace,et al.  Geophysical Constraints on the Relationship Between Seamount Subduction, Slow Slip, and Tremor at the North Hikurangi Subduction Zone, New Zealand , 2018, Geophysical Research Letters.

[6]  A. Niemeijer,et al.  Frictional Properties of Subduction Input Sediments at an Erosive Convergent Continental Margin and Related Controls on Décollement Slip Modes: The Costa Rica Seismogenesis Project , 2018, Journal of Geophysical Research: Solid Earth.

[7]  C. Collettini,et al.  Frictional Behavior of Input Sediments to the Hikurangi Trench, New Zealand , 2018, Geochemistry, Geophysics, Geosystems.

[8]  C. Williams,et al.  Earthquakes and Tremor Linked to Seamount Subduction During Shallow Slow Slip at the Hikurangi Margin, New Zealand , 2018, Journal of Geophysical Research: Solid Earth.

[9]  P. F. Fulton,et al.  International ocean discovery program expedition 375 preliminary report: Hikurangi subduction margin coring and observatories unlocking the secrets of slow slip through drilling to sample and monitor the forearc and subducting plate, 8 March - 5 May 2018 , 2018, International Ocean Discovery Program Preliminary Report.

[10]  Å. Fagereng,et al.  “Virtual shear box” experiments of stress and slip cycling within a subduction interface mélange , 2018 .

[11]  S. Schwartz,et al.  Tectonic tremor along the northern Hikurangi Margin, New Zealand, between 2010 and 2015 , 2016 .

[12]  T. Gerya,et al.  Crustal deformation dynamics and stress evolution during seamount subduction: High‐resolution 3‐D numerical modeling , 2016 .

[13]  K. Mochizuki,et al.  Slow slip near the trench at the Hikurangi subduction zone, New Zealand , 2016, Science.

[14]  C. Marone,et al.  Laboratory observations of slow earthquakes and the spectrum of tectonic fault slip modes , 2016, Nature Communications.

[15]  D. Saffer,et al.  The frictional, hydrologic, metamorphic and thermal habitat of shallow slow earthquakes , 2015 .

[16]  D. Barker,et al.  Fluid budgets along the northern Hikurangi subduction margin, New Zealand: the effect of a subducting seamount on fluid pressure , 2015 .

[17]  C. Collettini,et al.  Heterogeneous strength and fault zone complexity of carbonate-bearing thrusts with possible implications for seismicity , 2014 .

[18]  W. Power,et al.  Hikurangi margin tsunami earthquake generated by slow seismic rupture over a subducted seamount , 2014 .

[19]  R. Sutherland,et al.  Slow wavespeeds and fluid overpressure in a region of shallow geodetic locking and slow slip, Hikurangi subduction margin, New Zealand , 2014 .

[20]  Kelin Wang,et al.  Invited review paper: Fault creep caused by subduction of rough seafloor relief , 2014 .

[21]  T. Plank.  4.17 – The Chemical Composition of Subducting Sediments , 2014 .

[22]  C. Williams,et al.  Revised Interface Geometry for the Hikurangi Subduction Zone, New Zealand , 2013 .

[23]  A. Kopf,et al.  Slip weakening as a mechanism for slow earthquakes , 2013 .

[24]  Laura M. Wallace,et al.  Simultaneous long‐term and short‐term slow slip events at the Hikurangi subduction margin, New Zealand: Implications for processes that control slow slip event occurrence, duration, and migration , 2012 .

[25]  A. Rempel,et al.  Geologic heterogeneity can produce aseismic slip transients , 2012 .

[26]  N. Takeda,et al.  Propagation dynamics of seismic and aseismic slip governed by fault heterogeneity and Newtonian rheology , 2012 .

[27]  F. Hauff,et al.  Age and geochemistry of volcanic rocks from the Hikurangi and Manihiki oceanic Plateaus , 2010 .

[28]  R. Sibson,et al.  Mélange rheology and seismic style , 2010 .

[29]  P. Barnes,et al.  Seafloor structural geomorphic evolution of the accretionary frontal wedge in response to seamount subduction, Poverty Indentation, New Zealand , 2010 .

[30]  D. Barker,et al.  Seismic reflection character of the Hikurangi subduction interface, New Zealand, in the region of repeated Gisborne slow slip events , 2008 .

[31]  J. Greinert,et al.  Tectonic and geological framework for gas hydrates and cold seeps on the Hikurangi subduction margin, New Zealand , 2008 .

[32]  R. von Huene.  When Seamounts Subduct , 2008, Science.

[33]  B. Davy,et al.  Hikurangi Plateau: Crustal structure, rifted formation, and Gondwana subduction history , 2008 .

[34]  J. Rice,et al.  Spontaneous and triggered aseismic deformation transients in a subduction fault model , 2007 .

[35]  Laura M. Wallace,et al.  Subduction zone coupling and tectonic block rotations in the North Island, New Zealand , 2004 .

[36]  A. Kato,et al.  High Pore Fluid Pressure May Cause Silent Slip in the Nankai Trough , 2004, Science.

[37]  T. Webb,et al.  Source parameters of large historical (1918-1962) earthquakes, South Island, New Zealand , 2003 .

[38]  G. Lamarche,et al.  The giant Ruatoria debris avalanche on the northern Hikurangi margin, New Zealand: Result of oblique seamount subduction , 2001 .

[39]  J. Malavieille,et al.  Deformation of accretionary wedges in response to seamount subduction: Insights from sandbox experiments , 2000 .

[40]  B. Pelletier,et al.  From oblique subduction to intra-continental transpression: Structures of the southern Kermadec-Hikurangi margin from multibeam bathymetry, side-scan sonar and seismic reflection , 1996 .