scholarly journals Effects of plate bending and fault strength at subduction zones on plate dynamics

1999 ◽  
Vol 104 (B8) ◽  
pp. 17551-17571 ◽  
Author(s):  
Clinton P. Conrad ◽  
Bradford H. Hager
2020 ◽  
Author(s):  
Ylona van Dinther

<p><span>The strength of faults is subject of an important debate throughout various Earth Scientific disciplines. Different scientific communities have different perspectives with respect to appropriate values for friction coefficients μ. Geodynamicists with a long-term perspective require very low effective strengths (μ<0.05), while at the same time realizing mountains need to be sustained as well. Geologists and seismologists typically start from Byerlee friction coefficients of 0.6<μ<0.85, whereas rock mechanics experiments at high seismic slip rates show short-term low dynamic friction values of 0.03<μ<0.3. Here I show that both long- and short-term approaches can be made more compatible through considering that a regional or global frictional strength should be approached as a strain-averaged quantity. Doing this accounts for large variations of strain in both time and space. What matters for large-scale models is that most deformation occurs over a very small space and time during which friction is exceptionally low, thus making the representative long-term strength low. This is supported by seismo-thermo-mechanical models that self-consistently simulate the dynamics of both long-term subduction and short-term seismogenesis. The latter sustain mountain building, while representative earthquake-like events occur on faults with pore fluid pressure-effective static friction coefficients between 0.125 and 0.005 (or 0.75<Pf/Ps<0.99). These low friction values suggest faults are weak and suggest the dominant role of fluid pressures in weakening faults in subduction zones. This is confirmed in analytical considerations based on mechanical energy dissipation, which provide an equation to calculate the long-term fault strength as a strain-average quantity. Constraining the four parameters in this equation by observations confirms that fluid weakening is more important for long-term weakening than dynamic frictional weakening and low static friction coefficients. From the short-term perspective of modeling earthquake rupture dynamics it is now also becoming evident that fluid overpressured faults are preferable. They namely facilitate the incorporation of laboratory-observed dynamic weakening (70-90%) by limiting the stress drop to reasonable values. In summary, this cross-scale perspective supports long-term effective friction values in the range of about 0.03 to 0.2.</span></p>


2015 ◽  
Vol 37 ◽  
pp. 61-64
Author(s):  
Marco Scambelluri ◽  
Enrico Cannaò ◽  
Mattia Gilio ◽  
Marguerite Godard

2019 ◽  
Vol 50 (6) ◽  
pp. 673-678
Author(s):  
Vladimir Ivanovich Lysukhin ◽  
Julian Fedotovich Yaremchuk

1986 ◽  
Author(s):  
N. SARIGUL ◽  
M. KHONSARI ◽  
K. HASSAN

2018 ◽  
Author(s):  
David Fernández-Blanco

Orogenic plateaus have raised abundant attention amongst geoscientists during the last decades, offering unique opportunities to better understand the relationships between tectonics and climate, and their expression on the Earth’s surface.Orogenic plateau margins are key areas for understanding the mechanisms behind plateau (de)formation. Plateau margins are transitional areas between domains with contrasting relief and characteristics; the roughly flat elevated plateau interior, often with internally drained endorheic basins, and the external steep areas, deeply incised by high-discharge rivers. This thesis uses a wide range of structural and tectonic approaches to investigate the evolution of the southern margin of the Central Anatolian Plateau (CAP), studying an area between the plateau interior and the Cyprus arc. Several findings are presented here that constrain the evolution, timing and possible causes behind the development of this area, and thus that of the CAP. After peneplanation of the regional orogeny, abroad regional subsidence took place in Miocene times in the absence of major extensional faults, which led to the formation of a large basin in the northeast Mediterranean. Late Tortonian and younger contractional structures developed in the interior of the plateau, in its margin and offshore, and forced the inversion tectonics that fragmented the early Miocene basin into the different present-day domains. The tectonic evolution of the southern margin of the CAP can be explained based on the initiation of subduction in south Cyprus and subsequent thermo-mechanical behavior of this subduction zone and the evolving rheology of the Anatolian plate. The Cyprus slab retreat and posterior pull drove subsidence first by relatively minor stretching of the crust and then by its flexure. The growth by accretion and thickening of the upper plate, and that of the associated forearc basins system, caused by accreting sediments, led to rheological changes at the base of the crust that allowed thermal weakening, viscous deformation, driving subsequent surface uplift and raising the modern Taurus Mountains. This mechanism could be responsible for the uplifted plateau-like areas seen in other accretionary margins. ISBN: 978-90-9028673-0


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