scholarly journals Characterizing fault roughness—Are faults rougher at long or short wavelengths?

2021 ◽  
Author(s):  
Nicholas M. Beeler
Keyword(s):  
Fault Roughness

High-frequency ground-motion variability for rough-fault ruptures  

2021 ◽  
Author(s):  
Jagdish Chandra Vyas ◽  
Martin Galis ◽  
Paul Martin Mai
Keyword(s):  
Ground Motion ◽  
Large Scale ◽  
Earthquake Ground Motion ◽  
Small Scale ◽  
Dynamic Rupture ◽  
Roughness Effects ◽  
Ground Shaking ◽  
Fault Surface ◽  
Fault Roughness ◽  
Ground Motion Variability

<p>Geological observations show variations in fault-surface topography not only at large scale (segmentation) but also at small scale (roughness). These geometrical complexities strongly affect the stress distribution and frictional strength of the fault, and therefore control the earthquake rupture process and resulting ground-shaking. Previous studies examined fault-segmentation effects on ground-shaking, but our understanding of fault-roughness effects on seismic wavefield radiation and earthquake ground-motion is still limited.  </p><p>In this study we examine the effects of fault roughness on ground-shaking variability as a function of distance based on 3D dynamic rupture simulations. We consider linear slip-weakening friction, variations of fault-roughness parametrizations, and alternative nucleation positions (unilateral and bilateral ruptures). We use generalized finite difference method to compute synthetic waveforms (max. resolved frequency 5.75 Hz) at numerous surface sites  to carry out statistical analysis.  </p><p>Our simulations reveal that ground-motion variability from unilateral ruptures is almost independent of  distance from the fault, with comparable or higher values than estimates from ground-motion prediction equations (e.g., Boore and Atkinson, 2008; Campbell and Bozornia, 2008). However, ground-motion variability from bilateral ruptures decreases with increasing distance, in contrast to previous studies (e.g., Imtiaz et. al., 2015) who observe an increasing trend with distance. Ground-shaking variability from unilateral ruptures is higher than for bilateral ruptures, a feature due to intricate seismic radiation patterns related to fault roughness and hypocenter location. Moreover, ground-shaking variability for rougher faults is lower than for smoother faults. As fault roughness increases the difference in ground-shaking variabilities between unilateral and bilateral ruptures increases. In summary, our simulations help develop a fundamental understanding of ground-motion variability at high frequencies (~ 6 Hz) due small-scale geometrical fault-surface variations.</p>

scholarly journals Constraints from fault roughness on the scale-dependent strength of rocks

Geology ◽  
2015 ◽  
Vol 44 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Emily E. Brodsky ◽  
James D. Kirkpatrick ◽  
Thibault Candela
Keyword(s):  
Fault Roughness

What allows seismic events to grow big?: Insights from b-value and fault roughness analysis in laboratory stick-slip experiments

Geology ◽  
2017 ◽  
Vol 45 (9) ◽  
pp. 815-818 ◽  
Author(s):  
Thomas H.W. Goebel ◽  
Grzegorz Kwiatek ◽  
Thorsten W. Becker ◽  
Emily E. Brodsky ◽  
Georg Dresen
Keyword(s):  
B Value ◽  
Seismic Events ◽  
Stick Slip ◽  
Fault Roughness ◽  
Roughness Analysis

scholarly journals Influence of fault roughness on surface displacement: from numerical simulations to coseismic slip distributions

2019 ◽  
Vol 220 (3) ◽  
pp. 1857-1877 ◽  
Author(s):  
Lucile Bruhat ◽  
Yann Klinger ◽  
Amaury Vallage ◽  
Eric M Dunham
Keyword(s):  
Shear Stress ◽  
Numerical Simulations ◽  
Spectral Characteristics ◽  
Field Studies ◽  
Dynamic Rupture ◽  
Coseismic Slip ◽  
Fault Roughness ◽  
Critical Wavelength ◽  
Self Similar ◽  
Background Shear

SUMMARY Field studies have characterized natural faults as rough, non-planar surfaces at all scales. Fault roughness induces local stress perturbations during slip, which dramatically affect rupture behaviour, resulting in slip heterogeneity. However, the relation between fault roughness and slip heterogeneity remains a key knowledge gap between current numerical and field studies. In this study, we analyse numerical simulations of earthquake rupture to determine how roughness influences final slip. Using a rupture catalogue containing thousands of dynamic rupture simulations on band-limited self-similar fractal fault profiles with varying roughness and background shear stress levels, we quantify how fault roughness affects the spectral characteristics of the resulting slip distribution. We find that slip distributions become increasingly more self-affine, that is, containing more short wavelength fluctuations as compared to the self-similar fault profiles, as roughness increases. We also find that, at very short wavelengths (<1 km), the fractal dimension of the slip distributions dramatically changes with increasing roughness, background shear stress, and rupture speed (sub-Rayleigh versus supershear). The existence of a critical wavelength around 1 km, under which more short wavelengths are either preserved or created, suggests the role of rupture process and dynamic effects, together with fault geometry, in controlling the final slip distributions. The same spectral analysis is performed on high-resolution coseismic surface slip distributions from a catalogue of real strike-slip earthquakes. Compared to numerical simulations, all earthquakes feature slip distributions that are much more self-affine than the slip distributions from numerical simulations. A different critical wavelength, here around 5–6 km, appears, potentially informing about a critical asperity length. While we show here that the relation between fault roughness and slip is much more complex than expected, this study is a first attempt at using statistical analyses of numerical simulations on rough faults to investigate observed coseismic slip distributions.

scholarly journals Fault slip distribution and fault roughness

2011 ◽  
Vol 187 (2) ◽  
pp. 959-968 ◽  
Author(s):  
Thibault Candela ◽  
François Renard ◽  
Jean Schmittbuhl ◽  
Michel Bouchon ◽  
Emily E. Brodsky
Keyword(s):  
Fault Slip ◽  
Slip Distribution ◽  
Fault Roughness ◽  
Fault Slip Distribution

Stress Drop during Earthquakes: Effect of Fault Roughness Scaling

2011 ◽  
Vol 101 (5) ◽  
pp. 2369-2387 ◽  
Author(s):  
T. Candela ◽  
F. Renard ◽  
M. Bouchon ◽  
J. Schmittbuhl ◽  
E. E. Brodsky
Keyword(s):  
Stress Drop ◽  
Fault Roughness

scholarly journals Characterization of Fault Roughness at Various Scales: Implications of Three-Dimensional High Resolution Topography Measurements

2009 ◽  
pp. 1817-1851 ◽  
Author(s):  
Thibault Candela ◽  
François Renard ◽  
Michel Bouchon ◽  
Alexandre Brouste ◽  
David Marsan ◽  
...  
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Fault Roughness

Accounting for Fault Roughness in Pseudo-Dynamic Ground-Motion Simulations

2017 ◽  
Vol 174 (9) ◽  
pp. 3419-3450 ◽  
Author(s):  
P. Martin Mai ◽  
Martin Galis ◽  
Kiran K. S. Thingbaijam ◽  
Jagdish C. Vyas ◽  
Eric M. Dunham
Keyword(s):  
Ground Motion ◽  
Ground Motion Simulations ◽  
Fault Roughness
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