scholarly journals Dynamic Rupture Modeling to Investigate the Role of Fault Geometry in Jumping Rupture Between Parallel‐Trace Thrust Faults

2019 ◽  
Vol 109 (6) ◽  
pp. 2168-2186 ◽  
Author(s):  
Paul Peshette ◽  
Julian Lozos ◽  
Doug Yule ◽  
Eileen Evans
Keyword(s):  
Near Field ◽  
Stress Conditions ◽  
Parameter Study ◽  
Thrust Faults ◽  
Dynamic Rupture ◽  
Long Distance ◽  
Fault Strength ◽  
Stress Changes ◽  
Dip Angle ◽  
3D Finite Element Method

Abstract Investigations of historic surface‐rupturing thrust earthquakes suggest that rupture can jump from one fault to another up to 8 km away. Additionally, there are observations of jumping rupture between thrust faults ∼50  km apart. In contrast, previous modeling studies of thrust faults find a maximum jumping rupture distance of merely 0.2 km. Here, we present a dynamic rupture modeling parameter study that attempts to reconcile these differences and determines geometric and stress conditions that promote jumping rupture. We use the 3D finite‐element method to model rupture on pairs of thrust faults with parallel surface traces and opposite dip orientations. We vary stress drop and fault strength ratio to determine conditions that produce jumping rupture at different dip angles and different minimum distance between faults. We find that geometry plays an essential role in determining whether or not rupture will jump to a neighboring thrust fault. Rupture is more likely to jump between faults dipping toward one another at steeper angles, and the behavior tapers down to no rupture jump in shallow dip cases. Our variations of stress parameters emphasize these toward‐orientation results. Rupture jump in faults dipping away from one another is complicated by variations of stress conditions, but the most prominent consistency is that for mid‐dip angle faults rupture rarely jumps. If initial stress conditions are such that they are already close to failure, the possibility of a long‐distance jump increases. Our models call attention to specific geometric and stress conditions where the dynamic rupture front is the most important to potential for jumping rupture. However, our models also highlight the importance of near‐field stress changes due to slip. According to our modeling, the potential for rupture to jump is strongly dependent on both dip angle and orientation of faults.

scholarly journals Surface Displacement and Ground Motion from Dynamic Rupture Models of Thrust Faults with Variable Dip Angles and Burial Depths

2020 ◽  
Vol 110 (6) ◽  
pp. 2599-2618
Author(s):  
Sirena Ulloa ◽  
Julian C. Lozos
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Ground Motions ◽  
Ground Surface ◽  
Surface Displacement ◽  
Initial Stresses ◽  
Thrust Faults ◽  
Dynamic Rupture ◽  
Blind Thrust ◽  
Dip Angle

ABSTRACT Thrust-fault earthquakes are particularly hazardous in that they produce stronger ground motion than normal or strike-slip events of the same magnitude due to a combination of hanging-wall effects, vertical asymmetry, and higher stress drop due to compression. In addition, vertical surface displacement occurs in both blind-thrust and emergent thrust ruptures, and can potentially damage lifelines and infrastructure. Our 3D dynamic rupture modeling parameter study focuses on planar thrust faults of varying dip angles, and burial depth establishes a physics-based understanding of how ground motion and permanent ground surface displacement depend on these geometrical parameters. We vary dip angles from 20° to 70° and burial depths from 0 to 5 km. We conduct rupture models on these geometries embedded in a homogeneous half-space, using different stress drops but fixed frictional parameters, and with homogeneous initial stresses versus stresses tapered toward the ground surface. Ground motions decrease as we bury the fault under homogeneous initial stresses. In contrast, under tapered initial stresses, ground motions increase in blind-thrust faults as we bury the fault, but are still the highest in emergent faults. As we steepen dip angle, peak particle velocities in the homogeneous stress case generally increase in emergent faults but decrease in blind-thrust faults. Meanwhile, ground motion consistently increases with steepening dip angle under the stress gradient. We find that varying stress drop has a considerable scalar effect on both ground motion and permanent surface displacement, whereas changing fault strength has a negligible effect. Because of the simple geometry of a planar fault, our results can be applied to understanding basic behavior of specific real-world thrust faults.

scholarly journals Stress Changes on the Garlock Fault during and after the 2019 Ridgecrest Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1752-1764 ◽  
Author(s):  
Marlon D. Ramos ◽  
Jing Ci Neo ◽  
Prithvi Thakur ◽  
Yihe Huang ◽  
Shengji Wei
Keyword(s):  
Near Field ◽  
Earthquake Swarm ◽  
Local Stress ◽  
Stress Change ◽  
Earthquake Sequence ◽  
Dynamic Rupture ◽  
Eastern California Shear Zone ◽  
Stress Changes ◽  
Garlock Fault ◽  
Insight Into

ABSTRACT The recent 2019 Ridgecrest earthquake sequence in southern California jostled the seismological community by revealing a complex and cascading foreshock series that culminated in a Mw 7.1 mainshock. But the central Garlock fault, despite being located immediately south of this sequence, did not coseismically fail. Instead, the Garlock fault underwent postseismic creep and exhibited a sizeable earthquake swarm. The dynamic details of the rupture process during the mainshock are largely unknown, as is the amount of stress needed to bring the Garlock fault to failure. We present an integrated view of how stresses changed on the Garlock fault during and after the mainshock using a combination of tools including kinematic slip inversion, Coulomb stress change (ΔCFS), and dynamic rupture modeling. We show that positive ΔCFSs cannot easily explain observed aftershock patterns on the Garlock fault but are consistent with where creep was documented on the central Garlock fault section. Our dynamic model is able to reproduce the main slip asperities and kinematically estimated rupture speeds (≤2  km/s) during the mainshock, and suggests the temporal changes in normal and shear stress on the Garlock fault were the greatest near the end of rupture. The largest static and dynamic stress changes on the Garlock fault we observe from our models coincide with the creeping region, suggesting that positive stress perturbations could have caused this during or after the mainshock rupture. This analysis of near-field stress-change evolution gives insight into how the Ridgecrest sequence influenced the local stress field of the northernmost eastern California shear zone.

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

scholarly journals Rupture-dependent breakdown energy in fault models with thermo-hydro-mechanical processes

2020 ◽  
Author(s):  
Valère Lambert ◽  
Nadia Lapusta
Keyword(s):  
Material Property ◽  
Numerical Models ◽  
Slip Rate ◽  
Shear Cracks ◽  
Dynamic Rupture ◽  
Rupture Dynamics ◽  
Stress Changes ◽  
History Of ◽  
Thermal Pressurization ◽  
Pass Through

Abstract. Substantial insight into earthquake source processes has resulted from considering frictional ruptures analogous to cohesive-zone shear cracks from fracture mechanics. This analogy holds for slip-weakening representations of fault friction that encapsulate the resistance to rupture propagation in the form of breakdown energy, analogous to fracture energy, prescribed in advance as if it were a material property of the fault interface. Here, we use numerical models of earthquake sequences with enhanced weakening due to thermal pressurization of pore fluids to show how accounting for thermo-hydro-mechanical processes during dynamic shear ruptures makes breakdown energy rupture-dependent. We find that local breakdown energy is neither a constant material property nor uniquely defined by the amount of slip attained during rupture, but depends on how that slip is achieved through the history of slip rate and dynamic stress changes during the rupture process. As a consequence, the frictional breakdown energy of the same location along the fault can vary significantly in different earthquake ruptures that pass through. These results suggest the need for re-examining the assumption of pre-determined frictional breakdown energy common in dynamic rupture modeling and for better understanding of the factors that control rupture dynamics in the presence of thermo-hydro-mechanical processes.

Stress field perturbations from faults

2021 ◽  
Author(s):  
Karsten Reiter ◽  
Oliver Heidbach
Keyword(s):  
Stress Field ◽  
Stress Tensor ◽  
Distance Effect ◽  
Point Of View ◽  
Horizontal Line ◽  
Complex Behaviour ◽  
Numerical Resolution ◽  
Stress Changes ◽  
Fault Properties ◽  
Dip Angle

<p>Faults are crucial structures in the subsurface with respect to seismic hazards or the exploitation of the subsurface. However, even though it is clear that the released elastic energy changes the stress field, it is not well known at what distance these change leave a significant imprint on the stress tensor components. In particular, it is assumed that stress tensor rotations are a measure of these changes. Furthermore, from a technical point of view, the implementation of faults in geomechanical models is a challenging task. There are several implementation concepts are to mimic faults in geomechanical models. The two main classes are the continuous approach (soft of low plastic elements) and the discontinuous approach (contact surfaces). However, only partial aspects of the complex behaviour of faults or fault zones are represented by these techniques.</p><p>Knowing this limitation, we investigate the influence of the implementation concepts, fault properties and numerical resolution on the resulting stress field in the vicinity of a fault. The main focus of the generic models is to investigate, up to which distance from a fault, significant stress changes of the stress tensor components can be observed. In doing so, the respective models undergo a deformation that produces a similar stress state. The resulting stress magnitudes are investigated along a horizontal line at a depth of 660m, parallel to the shortening direction.</p><p>The result indicates, that stress magnitude pattern varies significantly close to the modelled fault, depending on the used implementation concept. However, beyond 500 m distance from the fault, the changes in stresses are < 0.5 MPa, regardless of the concept. Even a significant coarser resolution causes comparable stress patterns and magnitudes away from the implemented fault. Similarly, the dip angle, as well as the strike angle, have little effect on the observed distance effect. For stiff rocks having a higher Young's modulus, significant stress changes can also exceed the distance of 1000 m away from the fault.</p><p>The results indicate, that faults alone have limited effect on the far-field stress pattern. On the other hand, data of stress magnitudes or the stress tensor orientation close to a fault (< 500 m) are most likely affected by the particular fault geometry and fault characteristics. This is also the case for the vertical stress magnitude.</p>

scholarly journals High precision epidermal radio frequency antenna via nanofiber network for wireless stretchable multifunction electronics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yufei Zhang ◽  
Zhihao Huo ◽  
Xiandi Wang ◽  
Xun Han ◽  
Wenqiang Wu ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Near Field ◽  
Transmission Efficiency ◽  
Stretchable Electronics ◽  
Information Communication ◽  
Long Distance ◽  
Human Machine Interaction ◽  
Natural Systems ◽  
Content Recognition ◽  
Healthcare Monitoring

Abstract Recently, stretchable electronics combined with wireless technology have been crucial for realizing efficient human-machine interaction. Here, we demonstrate highly stretchable transparent wireless electronics composed of Ag nanofibers coils and functional electronic components for power transfer and information communication. Inspired by natural systems, various patterned Ag nanofibers electrodes with a net structure are fabricated via using lithography and wet etching. The device design is optimized by analyzing the quality factor and radio frequency properties of the coil, considering the effects of strain. Particularly, the wireless transmission efficiency of a five-turn coil drops by approximately only 50% at 10 MHz with the strain of 100%. Moreover, various complex functional wireless electronics are developed using near-field communication and frequency modulation technology for applications in content recognition and long-distance transmission (>1 m), respectively. In summary, the proposed device has considerable potential for applications in artificial electronic skins, human healthcare monitoring and soft robotics.

Near-field spectral analysis of data-integrative dynamic rupture earthquake simulations of the 1992 Landers earthquake

2020 ◽  
Author(s):  
Nico Schliwa ◽  
Alice-Agnes Gabriel
Keyword(s):  
Spectral Analysis ◽  
Ground Motion ◽  
Near Field ◽  
Slip Distribution ◽  
Corner Frequency ◽  
Dynamic Rupture ◽  
Geophysical Research ◽  
Acoustic Sensing ◽  
Distributed Acoustic Sensing ◽  
Large Earthquakes

<p>The rise of observations from Distributed Acoustic Sensing (e.g., Zhan 2020) and high-rate GNSS networks (e.g., Madariaga et al., 2019) highlight the potential of dense ground motion observations in the near-field of large earthquakes. Here, spectral analysis of >100,000 synthetic near-field strong motion waveforms (up to 2 Hz) is presented in terms of directivity, corner frequency, fall-off rate, moment estimates and static displacements.</p><p>The waveforms are generated in 3‐D large-scale dynamic rupture simulations which incorporate the interplay of complex fault geometry, topography, 3‐D rheology and viscoelastic attenuation (Wollherr et al., 2019). A preferred scenario accounts for off-fault deformation and reproduces a broad range of observations, including final slip distribution, shallow slip deficits, and spontaneous rupture termination and transfers between fault segments. We examine the effects of variations in modeling parameterization within a suite of scenarios including purely elastic setups and models neglecting viscoelastic attenuation. </p><p>First, near-field corner frequency mapping implementing a novel spectral seismological misfit criterion reveals rays of elevated corner frequencies radiating from each slipping fault at 45 degree to rupture forward direction. The azimuthal spectral variations are specifically dominant in the vertical components indicating we map rays of direct P-waves prevailing (Hanks, 1980). The spatial variation in corner frequencies carries information on co-seismic fault segmentation, slip distribution, focal mechanisms and stress drop. Second, spectral fall-off rates are variably inferred during picking the associated corner frequencies to identify the crossover from near-field to far-field spectral behaviour in dependence on distance and azimuth. Third, we determine static displacements with the help of near-field seismic spectra.</p><p>Our findings highlight the future potential of spectral analysis of spatially dense (low frequency) ground motion observations for inferring earthquake kinematics and understanding earthquake physics directly from near-field data; while synthetic studies are crucial to identify "what to look for" in the vast amount of data generated.</p><p><em>References:</em></p><p>Hanks, T.C., 1980. The corner frequency shift, earthquake source models and Q.</p><p>Madariaga, R., Ruiz, S., Rivera, E., Leyton, F. and Baez, J.C., 2019. Near-field spectra of large earthquakes. Pure and Applied Geophysics, 176(3), pp.983-1001.</p><p>Wollherr, S., Gabriel, A.-A. and Mai, P.M., 2019.  Landers 1992 “reloaded”: Integrative dynamic earthquake rupture modeling. Journal of Geophysical Research: Solid Earth, 124(7), pp.6666-6702.</p><p>Zhan, Z., 2020. Distributed Acoustic Sensing Turns Fiber‐Optic Cables into Sensitive Seismic Antennas. Seismological Research Letters, 91(1), pp.1-15.</p>

scholarly journals Analysis of long distance wakes behind a row of turbines – a parameter study

2014 ◽  
Vol 524 ◽  
pp. 012152 ◽  
Author(s):  
O Eriksson ◽  
K Nilsson ◽  
S-P Breton ◽  
S Ivanell
Keyword(s):  
Parameter Study ◽  
Long Distance

scholarly journals The spatial-temporal total friction coefficient of the fault viewed from the seismo-electromagnetic theory

2019 ◽  
Author(s):  
Patricio Venegas-Aravena ◽  
Enrique G. Cordaro ◽  
David Laroze
Keyword(s):  
Spatial Distribution ◽  
Friction Coefficient ◽  
Stress Drop ◽  
Electromagnetic Theory ◽  
Frictional Properties ◽  
Stress Changes ◽  
Plastic Rock ◽  
Dip Angle ◽  
Lithospheric Stress

Abstract. Recently, it has been shown theoretically how the lithospheric stress changes could be linked with magnetic anomalies, frequencies, spatial distribution and the magnetic-moment magnitude relation using the electrification of microfractures in the semi brittle-plastic rock regimen [Venegas-Aravena et al. Nat. Hazards Earth Syst. Sci. 19, 1639–1651 (2019)]. However, this Seismo-electromagnetic Theory still has not shown any relation, approach or changes in the fault's properties in order to be linked with the beginning of seismic rupture process itself. In this work we show the first and simple theoretical approach to one of the key parameters for seismic ruptures as is the friction coefficient and the stress drop. We use sigmoidal stress changes in the non-elastic regimen within lithosphere described before to figure out the temporal changes in frictional properties of faults. We also use a long term friction coefficient approximation that can depend on the fault dip angle, four parameters that weight the first and second stress derivative, the spatial distribution of the non-constant stress changes and the stress drop. It is found that the friction coefficient is not constant in time and evolve previous and after the earthquake occurs regardless of the (non-zero) weight used. When we use a dip angle close to 30 degrees and the contribution of the second derivative is more significant than the first derivative, the friction coefficient increase previous the earthquake. Then, the earthquake occurs and the friction drop. Finally, the friction coefficient increases and decreases after the earthquake. When there is no contribution of stress changes in the semi brittle-plastic regimen, no changes are expected in the friction coefficient.

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