The role of a keystone fault in triggering the complex El Mayor–Cucapah earthquake rupture

Fletcher, J. M.; Oskin, M. E.; Teran, O.

doi:10.1038/ngeo2660

Cited by 70 publications

(86 citation statements)

References 44 publications

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“…Earthquakes interaction and remobilization of relict faults represent a challenging issue for the accurate assessment of seismic hazard. Fault interaction may lead to multiple mainshock sequences as frequently observed worldwide (e.g., Fletcher et al, ; Hamling et al, ; Sieh et al, ).…”

Section: Discussionmentioning

confidence: 99%

Tectonics Inversions, Fault Segmentation, and Triggering Mechanisms in the Central Apennines Normal Fault System: Insights From High‐Resolution Velocity Models

et al. 2018

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The potential role of subsequent tectonic phases in reworking inherited geological structures is a key issue to unravel the seismotectonics of an area. This has a direct connection with fault segmentation, earthquakes maximum magnitude, and strong implications for seismic hazard assessment. The central Apennines (Italy) represent an exemplary case, since it developed because of the overprint of different deformational phases, producing potential conditions for episodic tectonic inversions and a very complex structural architecture. In this paper, we show how inherited compressional structures, still dominating the Apennines belt architecture, interfere with the active extension, having a direct connection with active seismotectonics. We present seismicity and new velocity tomograms of an 80‐km‐long section of the normal fault system activated during the 2009 and 2016–2018 seismic sequences. The joint interpretation highlights how the extensional seismic sequences partially reactivated inherited compressive structures, which have not an undisputable relationship with the surficial geological setting. Complexity deriving from the irregular geometry of normal faults and inverted thrust ramps is responsible for the observed intense fragmentation of the extensional system. Fluid overpressure seems to be a viable mechanism behind the partial remobilization of unbroken segments of the fault system.

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Section: Discussionmentioning

confidence: 99%

Tectonics Inversions, Fault Segmentation, and Triggering Mechanisms in the Central Apennines Normal Fault System: Insights From High‐Resolution Velocity Models

et al. 2018

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“…The Roscoe and Coulomb angles are upper and lower bounds, and the Arthur angle is defined as the mean of these two angles (Arthur et al, ). Despite the general agreement on these failure criteria, many natural faults deviate substantially from their predictions (Anderson, ; Fletcher et al, ; Hardebeck & Michael, ; Perrin, Manighetti, Gaudemer, et al, ; Scholz et al, ; Sibson, ; Sibson et al, ; Townend & Zoback, ). One reason for this discrepancy might be a long‐term rotation of the stress field surrounding the fault.…”

Section: Introductionmentioning

confidence: 99%

Seismic and Aseismic Fault Growth Lead to Different Fault Orientations

et al. 2019

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Orientations of natural fault systems are subject to large variations. They often contradict classical Coulomb failure theory as they are misoriented relative to the regional Andersonian stress field. This is ascribed to local effects of structural or stress heterogeneities and reorientations of structures or stresses on the long term. To better understand the relation between fault orientation and regional stresses, we simulate spontaneous fault growth and its effect on the stress field. Our approach incorporates earthquake rupture dynamics, viscoelastoplastic brittle deformation and a rate‐ and state‐dependent friction formulation in a continuum mechanics framework. We investigate how strike‐slip faults orient according to local and far‐field stresses during their growth. We identify two modes of fault growth, seismic and aseismic, distinguished by different fault angles and slip velocities. Seismic fault growth causes a significant elevation of dynamic stresses and friction values ahead of the propagating fault tip. These elevated quantities result in a greater strike angle relative to the maximum principal regional stress than that of a fault segment formed aseismically. When compared to the near‐tip time‐dependent stress field the fault orientations produced by both growth modes follow the classical failure theory. We demonstrate how the two types of fault growth may be distinguished in natural faults by comparing their angles relative to the original regional maximum principal stress. A stress field analysis of the Landers‐Kickapoo fault suggests that an angle greater than ∼25° between two faults indicates seismic fault growth.

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“…These data have given rise to studies of both the coseismic and postseismic processes for this event, including observations of triggered seismicity and slip in the region (Castro & Ben‐Zion, ; Castro et al, ; Donnellan et al, ; Fletcher et al, ; Fletcher et al, ; Gonzalez‐Ortega et al, ; Graves & Aagaard, ; Hauksson et al, ; Hines & Hetland, ; Huang et al, ; Kroll et al, ; Oskin et al, ; Pollitz et al, ; Rollins et al, ; Rymer et al, ; Spinler et al, ; M. Wei et al, ; S. Wei et al, ). The earthquake has been variously characterized as both “superficially simple” (S. Wei et al, ) and “complex” (Fletcher et al, ). The differences may arise from the fact that different approaches using different data sets may focus on different aspects of the earthquake and draw different conclusions on its complexity.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Rupture Modeling of the M7.2 2010 El Mayor‐Cucapah Earthquake: Comparison With a Geodetic Model

et al. 2017

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The 2010 Mw 7.2 El Mayor‐Cucapah earthquake is the largest event recorded in the broader Southern California‐Baja California region in the last 18 years. Here we try to analyze primary features of this type of event by using dynamic rupture simulations based on a multifault interface and later compare our results with space geodetic models. Our results show that starting from homogeneous prestress conditions, slip heterogeneity can be achieved as a result of variable dip angle along strike and the modulation imposed by step over segments. We also considered effects from a topographic free surface and find that although this does not produce significant first‐order effects for this earthquake, even a low topographic dome such as the Cucapah range can affect the rupture front pattern and fault slip rate. Finally, we inverted available interferometric synthetic aperture radar data, using the same geometry as the dynamic rupture model, and retrieved the space geodetic slip distribution that serves to constrain the dynamic rupture models. The one to one comparison of the final fault slip pattern generated with dynamic rupture models and the space geodetic inversion show good agreement. Our results lead us to the following conclusion: in a possible multifault rupture scenario, and if we have first‐order geometry constraints, dynamic rupture models can be very efficient in predicting large‐scale slip heterogeneities that are important for the correct assessment of seismic hazard and the magnitude of future events. Our work contributes to understanding the complex nature of multifault systems.

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The role of a keystone fault in triggering the complex El Mayor–Cucapah earthquake rupture

Cited by 70 publications

References 44 publications

Tectonics Inversions, Fault Segmentation, and Triggering Mechanisms in the Central Apennines Normal Fault System: Insights From High‐Resolution Velocity Models

Tectonics Inversions, Fault Segmentation, and Triggering Mechanisms in the Central Apennines Normal Fault System: Insights From High‐Resolution Velocity Models

Seismic and Aseismic Fault Growth Lead to Different Fault Orientations

Dynamic Rupture Modeling of the M7.2 2010 El Mayor‐Cucapah Earthquake: Comparison With a Geodetic Model

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