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.

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

2020 ◽  
Vol 20 (5) ◽  
pp. 1485-1496
Author(s):  
Patricio Venegas-Aravena ◽  
Enrique G. Cordaro ◽  
David Laroze
Keyword(s):  
Spatial Distribution ◽  
Friction Coefficient ◽  
Stress Drop ◽  
Electromagnetic Theory ◽  
Earthquake Occurrence ◽  
Sigmoidal Functions ◽  
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 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.

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

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.

scholarly journals Stress Drop, Seismogenic Index and Fault Cohesion of Fluid-Induced Earthquakes

2021 ◽  
Author(s):  
Serge A. Shapiro ◽  
Carsten Dinske
Keyword(s):  
Stress Drop ◽  
Induced Seismicity ◽  
Quantitative Characteristic ◽  
High Stress ◽  
Operation Time ◽  
Average Stress ◽  
Induced Earthquakes ◽  
Effective Stresses ◽  
Seismicity Rates

AbstractSometimes, a rather high stress drop characterizes earthquakes induced by underground fluid injections or productions. In addition, long-term fluid operations in the underground can influence a seismogenic reaction of the rock per unit volume of the fluid involved. The seismogenic index is a quantitative characteristic of such a reaction. We derive a relationship between the seismogenic index and stress drop. This relationship shows that the seismogenic index increases with the average stress drop of induced seismicity. Further, we formulate a simple and rather general phenomenological model of stress drop of induced earthquakes. This model shows that both a decrease of fault cohesion during the earthquake rupture process and an enhanced level of effective stresses could lead to high stress drop. Using these two formulations, we propose the following mechanism of increasing induced seismicity rates observed, e.g., by long-term gas production at Groningen. Pore pressure depletion can lead to a systematic increase of the average stress drop (and thus, of magnitudes) due to gradually destabilizing cohesive faults and due to a general increase of effective stresses. Consequently, elevated average stress drop increases seismogenic index. This can lead to seismic risk increasing with the operation time of an underground reservoir.

Long-term changes in spatial distribution of birds responding to a group-selection timber harvest

2012 ◽  
Vol 36 (2) ◽  
pp. 313-327 ◽  
Author(s):  
Steven P. Campbell ◽  
Jack W. Witham ◽  
Malcolm L. Hunter
Keyword(s):  
Spatial Distribution ◽  
Group Selection ◽  
Timber Harvest ◽  
Long Term Changes

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

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

<p>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; Andrés-Martínez 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.</p>

Long-term modeling of phosphorus spatial distribution in the no-tilled soil profile

2019 ◽  
Vol 187 ◽  
pp. 119-134 ◽  
Author(s):  
Haixiao Li ◽  
Alain Mollier ◽  
Noura Ziadi ◽  
Aimé Jean Messiga ◽  
Yichao Shi ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Soil Profile

scholarly journals SPATIAL DISTRIBUTION OF THE FAUNA OF THE SOIL ON THE LONG-TERM SYSTEM OF DIRECT SOWING

2017 ◽  
Vol 2 (2) ◽  
pp. 16
Author(s):  
Jessica Zuanazzi Fioritti Corbo ◽  
Glécio Machado Siqueira ◽  
Sidney Rosa Vieira
Keyword(s):  
Spatial Distribution ◽  
Direct Sowing

scholarly journals Spatial Analysis of Seasonal Precipitation Using Various Interpolation Methods in the Euphrates Basin, Turkey

2021 ◽  
Author(s):  
Okan Mert Katipoğlu
Keyword(s):  
Spatial Distribution ◽  
Geographical Information Systems ◽  
Polynomial Interpolation ◽  
Estimation Method ◽  
Summer Precipitation ◽  
Winter Precipitation ◽  
Geographical Information ◽  
Seasonal Precipitation ◽  
Interpolation Methods

Abstract It is vital to accurately map the spatial distribution of precipitation, which is widely used in many fields such as hydrology, climatology, meteorology, ecology, and agriculture. In this study, it was aimed to reveal the spatial distribution of seasonal long-term average precipitation in the Euphrates Basin by using various interpolation methods. For this reason, Simple Kriging (SK), Ordinary Kriging (OK), Universal Kriging (UK), Ordinary CoKriging (OCK), Empirical Bayesian Kriging (EBK), Radial Basis Functions (Completely Regularized Spline (CRS), Thin Plate Spline (TPS), Multiquadratic, Inverse Multiquadratic (IM), Spline with Tensor (ST)), Local Polynomial Interpolation (LPI), Global Polynomial Interpolation (GPI), Inverse Distance Weighting (IDW) methods have been applied in the Geographical Information Systems (GIS) environment. Long-term seasonal precipitation averages between 1966 and 2017 are presented as input for the prediction of precipitation maps. The accuracy of the precipitation prediction maps created was based on root mean square error (RMSE) values obtained from the cross-validation tests. The method of precipitation by interpolation yielding the lowest RMSE was selected as the most appropriate method. As a result of the study, OCK in spring and winter precipitation, LPI in summer precipitation, and OK in autumn precipitation were determined as the most appropriate estimation method.

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