Highly variable coastal deformation in the 2016 MW7.8 Kaikōura earthquake reflects rupture complexity along a transpressional plate boundary

Clark, Kate; Nissen, Edwin; Howarth, Jamie; Hamling, I. J.; Mountjoy, Joshu; Ries, W.; Jones, Katherine D.; Goldstien, Sharyn J.; Cochran, Ursula; Villamor, Pilar; Hreinsdóttir, Sigrún; Litchfield, Nicola; Mueller, Christof; Berryman, Kelvin; Strong, Delia

doi:10.1016/j.epsl.2017.06.048

Cited by 178 publications

(232 citation statements)

References 35 publications

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“…Some suggest that rupture of the subduction interface contributed >50% of the earthquake's moment (Bai et al, 2017;Duputel & Rivera, 2017;Hollingsworth et al, 2017;Wang et al, 2018), while others suggest a much smaller contribution from the subduction zone (<30%; Clark et al, 2017;Hamling et al, 2017), if any (Cesca et al, 2017;Holden et al, 2017;Xu et al, 2018). Some suggest that rupture of the subduction interface contributed >50% of the earthquake's moment (Bai et al, 2017;Duputel & Rivera, 2017;Hollingsworth et al, 2017;Wang et al, 2018), while others suggest a much smaller contribution from the subduction zone (<30%; Clark et al, 2017;Hamling et al, 2017), if any (Cesca et al, 2017;Holden et al, 2017;Xu et al, 2018).…”

Section: Mechanisms Behind the Triggered Slow Slip And Afterslipmentioning

confidence: 99%

“…Interface afterslip is determined by a continuum representation of rate-strengthening fault creep using the formulation of Barbot et al (2009). We use the coseismic fault sources from Clark et al (2017) (modified from Hamling et al, 2017) for our forward models in RELAX, which includes <2 m of coseismic slip on the interface. Following Barbot et al (2009), we adjust the fault creep parameters to match the postseismic decay rate observed in the GPS (see supporting information).…”

Section: Mechanisms Behind the Triggered Slow Slip And Afterslipmentioning

confidence: 99%

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Triggered Slow Slip and Afterslip on the Southern Hikurangi Subduction Zone Following the Kaikōura Earthquake

Wallace

Hreinsdóttir

Ellis

et al. 2018

Geophysical Research Letters

111

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The 2016 MW7.8 Kaikōura earthquake ruptured a complex sequence of strike‐slip and reverse faults in New Zealand's northeastern South Island. In the months following the earthquake, time‐dependent inversions of Global Positioning System and interferometric synthetic aperture radar data reveal up to 0.5 m of afterslip on the subduction interface beneath the northern South Island underlying the crustal faults that ruptured in the earthquake. This is clear evidence that the far southern end of the Hikurangi subduction zone accommodates plate motion. The MW7.8 earthquake also triggered widespread slow slip over much of the subduction zone beneath the North Island. The triggered slow slip included immediate triggering of shallow (<15 km), short (2–3 weeks) slow slip events along much of the east coast, and deep (>30 km), long‐term (>1 year) slow slip beneath the southern North Island. The southern Hikurangi slow slip was likely triggered by large (0.5–1.0 MPa) static Coulomb stress increases.

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Section: Mechanisms Behind the Triggered Slow Slip And Afterslipmentioning

confidence: 99%

Section: Mechanisms Behind the Triggered Slow Slip And Afterslipmentioning

confidence: 99%

Triggered Slow Slip and Afterslip on the Southern Hikurangi Subduction Zone Following the Kaikōura Earthquake

Wallace

Hreinsdóttir

Ellis

et al. 2018

Geophysical Research Letters

111

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“…We use a finite fault approach (e.g., Hjörleifsdóttir et al, ) where a set of point sources are used to represent the spatiotemporal evolution of slip on the faults ruptured during the Kaikōura earthquake. To reduce the degree of unknowns, we use an a priori fault slip model (Clark et al, ) as a constraint for the fault geometry and the final slip distribution and only vary the rupture initiation times of major fault segments and rise time distribution, with the local rise time being proportional to the square root of slip (e.g., Aagaard et al, ; Graves & Pitarka, ) (Figure a). In this slip model, there are a total of 21 planar fault segments with their dip constrained by geologically estimated values (Hamling et al, ).…”

Section: Kinematic Slip History Inferred From Forward Wavefield Simulmentioning

confidence: 99%

“…Conversely, finite fault inversion requires several simplifying assumptions about the source and seismic velocity structure but its low computational cost enables exploration of a wide range of source parameters. Since geodetically derived slip models of the Kaikōura earthquake indicate a large degree of complexity of the ruptured fault system (Clark et al, ; Hamling et al, ), rupture‐time histories inferred from either technique are nonunique; hence, robust features are better identified from mutual features present in the results of both approaches.…”

Section: Introductionmentioning

confidence: 99%

The 2016 Kaikōura Earthquake Revealed by Kinematic Source Inversion and Seismic Wavefield Simulations: Slow Rupture Propagation on a Geometrically Complex Crustal Fault Network

Holden

Kaneko

D’Anastasio

et al. 2017

Geophysical Research Letters

102

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The 2016 Kaikōura (New Zealand) earthquake generated large ground motions and resulted in multiple onshore and offshore fault ruptures, a profusion of triggered landslides, and a regional tsunami. Here we examine the rupture evolution using two kinematic modeling techniques based on analysis of local strong‐motion and high‐rate GPS data. Our kinematic models capture a complex pattern of slowly (Vr < 2 km/s) propagating rupture from south to north, with over half of the moment release occurring in the northern source region, mostly on the Kekerengu fault, 60 s after the origin time. Both models indicate rupture reactivation on the Kekerengu fault with the time separation of ~11 s between the start of the original failure and start of the subsequent one. We further conclude that most near‐source waveforms can be explained by slip on the crustal faults, with little (<8%) or no contribution from the subduction interface.

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“…The longest records of temporal variability are from strike‐slip earthquakes, which show considerable variability, but perhaps less than expected for a Gutenberg‐Richter frequency‐magnitude distribution (Hecker et al, ). Maps of historic earthquake surface ruptures show dramatically variable displacements along strike for all slip senses (Clark et al, ; Crone et al, ; Liu‐Zeng et al, ; Rockwell & Klinger, ). Even in situations where piercing points are unambiguous, a small sample set (fewer than, say, 10 measurements) collected at random along a surface rupture is likely to misrepresent the true mean displacement because most ruptures have short sections where the displacement is many times greater than the mean (Biasi & Weldon, ).…”

Section: Introductionmentioning

confidence: 99%

Quantifying Uncertainty in Cumulative Surface Slip Along the Cucamonga Fault, a Crustal Thrust Fault in Southern California

McPhillips

Scharer

2018

JGR Solid Earth

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Studies of historic earthquake ground surface ruptures show that displacements along strike are spatially variable. As a result, latest Quaternary slip rates developed from a spatially restricted set of cumulative displacement measurements may not accurately represent fault velocity. Here we examine the uncertainties associated with slip on the Cucamonga Fault, which is part of a network of faults that have generated damaging historical earthquakes in and around Los Angeles, California. Numerous scarps along its ~25‐km length are well expressed on alluvial fans. We make 310 measurements of vertical separation across the scarps using lidar data. We show that the dispersion of the vertical separations cannot be explained by our best estimates of analytical uncertainties alone. Additional epistemic uncertainties are required. We find that the magnitude of the required epistemic uncertainty is typically larger than analytical uncertainty by a factor of 3 and typically about 22% of the maximum vertical separation. These relationships appear to hold at several spatial scales. We examine three potential sources of epistemic uncertainty and find that none among surface age uncertainty, fault dip, and anthropogenic landscape alteration is likely sufficient to explain the overdispersion of the data, which suggests differences in cumulative strain along the strike of the fault. We calculate a range of dip‐slip rates between 0.4 and 2.6 mm/year. In light of our results, we suggest that future thrust‐fault slip‐rate studies adopt an epistemic uncertainty of 22% of the maximum value for vertical separation measurements, unless there are sufficient data to demonstrate otherwise.

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Highly variable coastal deformation in the 2016 MW7.8 Kaikōura earthquake reflects rupture complexity along a transpressional plate boundary

Cited by 178 publications

References 35 publications

Triggered Slow Slip and Afterslip on the Southern Hikurangi Subduction Zone Following the Kaikōura Earthquake

Triggered Slow Slip and Afterslip on the Southern Hikurangi Subduction Zone Following the Kaikōura Earthquake

The 2016 Kaikōura Earthquake Revealed by Kinematic Source Inversion and Seismic Wavefield Simulations: Slow Rupture Propagation on a Geometrically Complex Crustal Fault Network

Quantifying Uncertainty in Cumulative Surface Slip Along the Cucamonga Fault, a Crustal Thrust Fault in Southern California

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