Earthquake Cycles in Fault‐Bend Folds

Sathiakumar, S.; Barbot, Sylvain; Hubbard, Judith

doi:10.1029/2019jb018557

Cited by 33 publications

(54 citation statements)

References 214 publications

(398 reference statements)

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“…Hence, their total slip scales with the characteristic weakening distance, as in

ϵ \propto \frac{L}{R},

where

1 ≲ L ≲ 10

cm is the characteristic weakening distance of rate‐and‐state friction in a range compatible with slow slip and R ∼ 50 km is the down‐dip rupture width, leading to estimates of potency density in the range of 0.01 to 3 microstrain. The overall variability of source properties, for example, two orders of magnitude for potency density, may be attributed to the presence of frictional contrast along the fault (Kaneko et al, 2010; Kaneko & Shearer, 2015), variability of earthquake slip due to the stress shadow of previous ruptures (Barbot, 2019b; Michel et al, 2017; Van Dither et al, 2013), morphological gradients (Qiu et al, 2016; Sathiakumar et al, 2020), variation of off‐fault damage (Cappa et al, 2014), differing coupling coefficients (Chounet & Vallée, 2018), or the activation of different weakening mechanisms (Cocco et al, 2016; Cattania & Segall, 2018; Kirkpatrick & Shipton, 2009).…”

Section: Discussionmentioning

confidence: 99%

“…Inversion of geodetic data for the spatial distribution of slip on a fault is also subject to fundamental limitations, notably due to the St. Venant principle that implies a decreasing resolution with increasing distance between source and observations. However, the deployment of increasingly large and dense geodetic observatories, the development of better analytic standards in inverse theory (Aster et al, 2012;Funning et al, 2014;Fukahata & Wright, 2008;Hang et al, 2020;Nocquet, 2018;Yabuki & Matsu'ura, 1992), and the joint inversion of complementary data sets, both geodetic and seismological, has increased the accuracy of slip distributions (Atzori & Antonioli, 2011;Amey et al, 2018;Barbot et al, 2013;Duputel et al, 2014;DeVries et al, 2017;Evans & Meade, 2012;Gombert et al, 2017Gombert et al, , 2018McGuire & Segall, 2003;Minson et al, 2014;Sathiakumar et al, 2017). For example, the large uncertainties associated with shallow slip near the trench during the 2011 Mw = 9.1 Tohoku, Japan, earthquake were largely reduced by considering tsunami data (e.g., Bletery et al, 2014;Jiang & Simons, 2016;Yamazaki et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Static Source Properties of Slow and Fast Earthquakes

2020

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The source characteristics of slow and fast earthquakes provide a window into the mechanical properties of faults. In particular, the average stress drop controls the evolution of friction, fault slip, and event magnitude. However, this important source property is typically inferred from the analysis of seismic waves and is subject to many epistemic uncertainties. Here, we investigate the source properties of 53 earthquakes and 17 slow-slip events on thrust and strike-slip faults in various tectonic settings using slip distributions constrained by geodesy in combination with other data. We determine the width, potency, and potency density of slow and fast earthquake sources based on static slip distributions. The potency density, defined conceptually as the ratio of average slip to rupture radius, is a measure of anelastic deformation with limited bias from rigidity differences across depths and tectonic settings. Strike-slip earthquakes have the highest potency density, varying from 20 to 500 microstrain. The potency density is on average lower on continental thrust faults and megathrusts, from 10 to 200 microstrain, with an algebraic decrease with centroid depth, indicative of systematic changes in dominant rupture processes with depth. Slow slip events represent an end-member style of rupture with low potency density and large rupture width. Significant variability in potency density of slow-slip events affects their moment-duration scaling. The variations of source properties across tectonic settings, depth, and rupture styles can be used to better constrain numerical simulations of seismicity and to assess the source characteristics of future earthquakes and slow slip events. Plain Language Summary Natural earthquakes reduce the stress that accumulates on faults due to plate tectonics. To better understand the variability of seismic hazards around active faults, we survey the properties of slow and fast earthquakes around the world. The potential of faults to concentrate large slip in the rupture area differs depending on the geological setting, the depth of the source, and the type of rupture. Earthquakes in a continental setting condense more slip in a given rupture area, particularly in transform faults like the San Andreas fault. Subduction zone earthquakes, although some of the largest events on Earth, generally distribute less slip over a wider area, but this varies as a function of depth. Slow earthquakes represent an extreme case of little slip distributed over a large area. The propensity of rupture characteristics to vary with fault type and depth may help forecast the hazards posed by future seismicity.

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“…Hence, their total slip scales with the characteristic weakening distance, as in

ϵ \propto \frac{L}{R},

where

1 ≲ L ≲ 10

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Static Source Properties of Slow and Fast Earthquakes

2020

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“…Some investigators argue that the succession of partial and full ruptures is a self-emergent behavior from the nonlinear dynamics of fault slip favored by wide seismogenic zones (Herrendörfer et al 2015;Michel et al 2017;Barbot 2019b). Others suggest the important role of local changes in the fault geometry (Qiu 2016;Hubbard et al 2016;Sathiakumar et al 2020). At subduction zones, where the megathrust traverses various geological formations, we expect a combination of these two factors to operate a strong control on the seismic cycle.…”

Section: Introductionmentioning

confidence: 92%

“…In particular, Ikari and Kopf (2017) highlight the velocity-weakening behavior of sedimentary muds at plate tectonic slip rates, which is a necessary condition for rupture self-nucleation. If the shallow layer is assumed frictionally unstable, other mechanisms may be invoked to explain segmentation, for example, the presence of rheological barriers (Kaneko et al 2010) or morphological gradients (Qiu 2016;Ong et al 2019;Sathiakumar et al 2020). Within this view, giant surface-breaking ruptures may represent the synchronous failure in a single event of otherwise isolated asperities (Yamanaka and Kikuchi 2004).…”

Section: Introductionmentioning

confidence: 99%

Frictional and structural controls of seismic super-cycles at the Japan trench

Barbot

2020

Earth Planets Space

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The diverse mechanical behaviors of subduction zones during the seismic cycle emerge from the nonlinear dynamics of a complex mechanical system with interacting brittle and ductile deformation. The 2011 Tohoku mega-quake represents the culmination of a super-cycle of partial and full ruptures of the plate interface, but the physical controls on the down-dip segmentation of the megathrust remain unclear. Here, we propose a two-dimensional rheological model of the Japan trench to explain the variability of earthquake size at the Miyagi section, in northern Honshu, during the last century. We simulate seismicity in a continuum with a physics-based rate-and state-dependent constitutive law for fault slip, producing aperiodic earthquake sequences with a power-law distribution of rupture sizes. Although some partial ruptures of the megathrust are the result of self-emergent behavior, others are structurally controlled. The 1978 and 2005 Mj∼ 7 interplate earthquakes took place in a metamorphic belt in the mantle wedge corner bounded up-dip by the arc Moho that constitutes a permanent structural boundary. We explain the succession of the great 1981 Mw = 7.1 and 2003 Mw = 6.9 earthquakes within the forearc and the 2011 giant earthquake as the natural response of a large continuously velocity-weakening fault with a small nucleation size. The shallow segment below the frontal prism only slips in giant through-going ruptures that unzip the whole velocity-weakening interface. The model consistently explains the size, recurrence time, and hypocenter location of historical earthquakes in the Miyagi segment, the slow-slip and foreshock preparatory phase of the 2011 Tohoku earthquake, the large slip near the trench during the giant rupture, and important features of its postseismic deformation. The complex patterns of seismicity at the Japan trench can be better understood by assimilating geological and geophysical observations at various periods of the seismic cycle within an explicative physical framework.

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“…Segment A. The top segment represents the intersection of the megathrust with the accretionary prism, a sedimentary sink characterized by intense off-fault deformation (Moore et al 1990;Hubbard et al 2015;Sathiakumar et al 2020), low rigidity (Sallarès and Ranero 2019), and particularly low static friction (e.g., Byrne and Fisher 1990;Cubas et al 2013). The shortening taken up by secondary faults and folds in the upper plate builds topography and reduces the long-term loading rate on the megathrust, resulting in a low rate of seismicity on the plate interface.…”

Section: Structural and Lithological Control On Megathrust Dynamicsmentioning

confidence: 99%

Structural control and system-level behavior of the seismic cycle at the Nankai Trough

Shi

Barbot

Wei

et al. 2020

Earth Planets Space

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The Nankai Trough in Southwest Japan exhibits a wide spectrum of fault slip, with long-term and short-term slowslip events, slow and fast earthquakes, all associated with different segments down the plate interface. Frictional and viscous properties vary depending on rock type, temperature, and pressure. However, what controls the downdip segmentation of the Nankai subduction zone megathrust and how the different domains of the subduction zone interact during the seismic cycle remains unclear. Here, we model a representative cross-section of the Nankai subduction zone offshore Shikoku Island where the frictional behavior is dictated by the structure and composition of the overriding plate. The intersections of the megathrust with the accretionary prism, arc crust, metamorphic belt, and upper mantle down to the asthenosphere constitute important domain boundaries that shape the characteristics of the seismic cycle. The mechanical interactions between neighboring fault segments and the impact from the long-term viscoelastic flow strongly modulate the recurrence pattern of earthquakes and slow-slip events. Afterslip penetrates down-dip and up-dip into slow-slip regions, leading to accelerated slow-slip cycles at depth and longlasting creep waves in the accretionary prism. The trench-ward migrating locking boundary near the bottom of the seismogenic zone progressively increases the size of long-term slow-slip events during the interseismic period. Fault dynamics is complex and potentially tsunami-genic in the accretionary region due to low friction, off-fault deformation, and coupling with the seismogenic zone.

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Earthquake Cycles in Fault‐Bend Folds

Cited by 33 publications

References 214 publications

Static Source Properties of Slow and Fast Earthquakes

Static Source Properties of Slow and Fast Earthquakes

Frictional and structural controls of seismic super-cycles at the Japan trench

Structural control and system-level behavior of the seismic cycle at the Nankai Trough

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