The spatial–temporal total friction coefficient of the fault viewed from the perspective of seismo-electromagnetic theory

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 semibrittle–plastic rock regime (Venegas-Aravena et al., 2019). However, this seismo-electromagnetic theory has not been connected with the fault's properties in order to be linked with the onset of the seismic rupture process itself. In this work we provide a simple theoretical approach to two of the key parameters for seismic ruptures which are the friction coefficient and the stress drop. We use sigmoidal functions to model the stress changes in the nonelastic regime within the lithosphere. We determine the temporal changes in frictional properties of faults. We also use a long-term friction coefficient approximation that depends on the fault dip angle and four additional parameters that weigh the first and second stress derivative, the spatial distribution of the nonconstant stress changes, and the stress drop. We found that the friction coefficient is not constant in time and evolves prior to and after the earthquake occurrence regardless of the (nonzero) weight used. When we use a dip angle close to 30∘ and the contribution of the second derivative is more significant than that of the first derivative, the friction coefficient increases prior to the earthquake. During the earthquake event the friction drops. Finally, the friction coefficient increases and decreases again after the earthquake occurrence. It is important to mention that, when there is no contribution of stress changes in the semibrittle–plastic regime, no changes are expected in the friction coefficient.

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

10.5194/nhess-2019-295 ◽

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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Simple Topographic Parameter Reveals the Along-Trench Distribution of Frictional Properties on a Shallow Plate Boundary Fault

10.21203/rs.3.rs-948355/v1 ◽

2021 ◽

Author(s):

Hiroaki Koge ◽

Juichiro Ashi ◽

Jin-Oh Park ◽

Ayumu Miyakawa ◽

Suguru Yabe

Keyword(s):

Spatial Distribution ◽

Friction Coefficient ◽

Subduction Zones ◽

Slope Angle ◽

Plate Boundary ◽

Boundary Fault ◽

Frictional Properties ◽

Topographic Parameter ◽

Dip Angle ◽

Taper Model

Abstract The critical taper model of a sedimentary wedge best describes the first-order mechanics of a subduction zone wedge. The tapered wedge geometry, which is conventionally defined by two parameters, the slope angle and the basal dip angle, is responsible for the strength of a megathrust. By applying this theoretical model to subduction zones, fault frictional properties and earthquake occurrences can be compared among subduction zones, and within a single subduction zone, the spatial distribution or temporal change of fault strength can be investigated. The slope angle can be accurately estimated from bathymetry data, but the basal dip angle must be inferred from the subsurface structure, and it requires highly accurate depth-converted seismic reflection profiles. Thus, application of the critical taper model is often limited by a lack of a sufficient number of highly accurate profiles, and the spatial distribution of frictional coefficients must be inferred from relatively few data, generally less than a dozen points. To improve this situation, we revisited the theoretical formula of the critical taper model. We found that the effect of the décollement dip angle β on the critical taper model of a sedimentary wedge is negligible when the pore fluid pressure ratio is high or internal friction is small, conditions which are met in many subduction zones. Therefore, this finding allows frictional variation to be approximated by using only the slope angle variation obtained from the bathymetry. We applied this approximation to the Japan Trench as an example of this approximation, and were able to estimate the friction coefficient distribution on the shallow plate boundary fault from 71 data points. We found that the area where the friction coefficient was smaller than the mean corresponded to the segment where a large coseismic shallow rupture occurred during the 2011 Tohoku-oki earthquake (Mw 9.0). This result shows that by approximating tapered wedge geometry using a simple topographic parameter that can be obtained from existing global bathymetry, we can quickly estimate the distribution of frictional properties on a plate boundary fault along a trench and related seismic activity.

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Fluctuating Lake Levels in Rift Basins and its Impact on Extensional Tectonics

10.5194/egusphere-egu21-10283 ◽

2021 ◽

Author(s):

April Allen Langhans ◽

Robert Moucha ◽

Michael Keith Paciga

Keyword(s):

Stress State ◽

Extensional Tectonics ◽

Lake Levels ◽

Rift Basins ◽

Stress Changes ◽

Response To Stress ◽

Potential Impact ◽

Extensional Model ◽

Lithospheric Stress ◽

Fully Coupled

The feedback between climate driven processes; weathering, erosion, sediment transport, and deposition, and extensional tectonics is limited to a few studies (Burov and Cloething, 1997; Burov and Poliakov, 2001; Bialas and Buck, 2009; Theunissen and Huismans, 2019; Andr&#233;s-Mart&#237;nez et al., 2019) despite these processes having been shown to impact the stress state and deformation along active orogens (Koons, 1989; Molnar and England, 1990; Avouac and Burov, 1996; Willett, 1999). Here we utilize a fully coupled landscape evolution and thermomechanical extensional model to investigate the potential impact on faulting and extension due to lake loading changes driven by changes in climate on processional timescales. Fault analyses focusing on heave, throw, and magnitude of dip on faults generated within each model are used to characterize individual faults response to stress changes and rift basin evolution. Preliminary results indicate that fluctuations in lake levels in response to climate change may impact the lithospheric stress state by changing both fault and basin geometries within an extensional basin.

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Fault dip angle determination with the ℛ criterion and coulomb stress changes associated with the 2015 M 7.9 Gorkha Nepal earthquake revealed by InSAR and GPS data

Tectonophysics ◽

10.1016/j.tecto.2016.08.024 ◽

2017 ◽

Vol 714-715 ◽

pp. 55-61 ◽

Cited By ~ 4

Author(s):

Haipeng Luo ◽

Ting Chen ◽

Caijun Xu ◽

Hailong Sha

Keyword(s):

Gps Data ◽

Coulomb Stress ◽

Coulomb Stress Changes ◽

Nepal Earthquake ◽

Stress Changes ◽

Dip Angle

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Fault parameters determined by near- and far-field data: The Wakasa Bay earthquake of March 26, 1963

Bulletin of the Seismological Society of America ◽

10.1785/bssa0640051369 ◽

1974 ◽

Vol 64 (5) ◽

pp. 1369-1382 ◽

Cited By ~ 1

Author(s):

Katsuyuki Abe

Keyword(s):

Effective Stress ◽

Stress Drop ◽

P Wave ◽

Slip Angle ◽

Polarization Angle ◽

S Wave ◽

Seismological Data ◽

Fault Parameters ◽

Wakasa Bay ◽

Dip Angle

Abstract The source process of the Wakasa Bay earthquake (M = 6.9, 35.80°N, 135.76°E, depth 4 km) which occurred near the west coast of Honshu Island, Japan, on March 26, 1963, is studied on the basis of the seismological data. Dynamic and static parameters of the faulting are determined by directly comparing synthetic seismograms with observed seismograms recorded at seismic near and far distances. The De Hoop-Haskell method is used for the synthesis. The average dislocation is determined to be 60 cm. The overall dislocation velocity is estimated to be 30 cm/sec, the rise time of the slip dislocation being determined as 2 sec. The other fault parameters determined, with supplementary data on the P-wave first motion, the S-wave polarization angle, and the aftershocks, are: source geometry, dip direction N 144°E, dip angle 68°, slip angle 22° (right-lateral strike-slip motion with some dip-slip component); fault dimension, 20 km length by 8 km width; rupture velocity, 2.3 km/sec (bilateral); seismic moment, 3.3 × 1025 dyne-cm; stress drop, 32 bars. The effective stress available to accelerate the fault motion is estimated to be about 40 bars. The approximate agreement between the effective stress and the stress drop suggests that most of the effective stress was released at the time of the earthquake.

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Stress field perturbations from faults

10.5194/egusphere-egu21-10155 ◽

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

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.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.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 <&#160;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.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 (<&#160;500&#160;m) are most likely affected by the particular fault geometry and fault characteristics. This is also the case for the vertical stress magnitude.

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

Bulletin of the Seismological Society of America ◽

10.1785/0120190003 ◽

2019 ◽

Vol 109 (6) ◽

pp. 2168-2186 ◽

Cited By ~ 2

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.

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Geomechanical modeling of induced seismicity source parameters and implications for seismic hazard assessment

Geophysics ◽

10.1190/geo2012-0102.1 ◽

2013 ◽

Vol 78 (1) ◽

pp. KS25-KS39 ◽

Cited By ~ 57

Author(s):

Bettina P. Goertz-Allmann ◽

Stefan Wiemer

Keyword(s):

Seismic Hazard ◽

Pore Pressure ◽

Stress Drop ◽

Induced Seismicity ◽

Critical Stress ◽

Source Parameters ◽

Differential Stress ◽

Geomechanical Properties ◽

Stress Changes ◽

Stress States

We simulate induced seismicity within a geothermal reservoir using pressure-driven stress changes and seismicity triggering based on Coulomb friction. The result is a forward-modeled seismicity cloud with origin time, stress drop, and magnitude assigned to each individual event. Our model includes a realistic representation of repeating event clusters, and is able to explain in principle the observation of reduced stress drop and increased [Formula: see text]-values near the injection point where pore-pressure perturbations are highest. The higher the pore-pressure perturbation, the less critical stress states still trigger an event, and hence the lower the differential stress is before triggering an event. Less-critical stress states result in lower stress drops and higher [Formula: see text]-values, if both are linked to differential stress. We are therefore able to establish a link between the seismological observables and the geomechanical properties of the source region and thus a reservoir. Understanding the geomechanical properties is essential for estimating the probability of exceeding a certain magnitude value in the induced seismicity and hence the associated seismic hazard of the operation. By calibrating our model to the observed seismicity data, we can estimate the probability of exceeding a certain magnitude event in space and time and study the effect of injection depth and crustal strength on the induced seismicity.

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