Slow slip

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Slip bursts during coalescence of slow slip events in Cascadia

Slip bursts during coalescence of slow slip events in Cascadia

perturbations, such as those generated by tides 17 . The southern migration of the northern slip front or the onset of the center one possibly reflects such long-distance interaction. Enhanced slip during coalescence episodes. Both merging phases are associated with a burst in moment rate release resulting from a combination of a growth of the slipping area filling the space between the two patches and an increase in daily slip velocity (Fig. 3 a). Moment release bursts result in an accel- eration of the daily incremental displacement at GPS sites located above the merging area, directly seen in the GPS data (Fig. 3 b). The period of merging between September 27 and October 5 (9 days) contributes to more than half (59%) of the total moment released during the entire sequence (47 days). Furthermore, peak moment rates on September 28 and October 4 represent a third (33%) of the moment released during the merging period. These ratios suggest a merging-induced burst-like behavior of slip at a daily time scale. Slip might, however, experience sub-daily var- iations. Indeed, analyses of seismic data indicate that micro- seismic activity, presumably driven by slow slip, is clustered in minute-to-hour-long bursts 18 , 19 . The daily incremental slip inferred here is likely an average of multiple shorter episodic events, with the implication that slip rates may punctually be significantly faster than the daily slip velocities inferred from our inversion.
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Friction experiments with elastography: the slow slip and the super-shear regimes

Friction experiments with elastography: the slow slip and the super-shear regimes

fig. 3). A low frequency signal, with a periodicity close to one second, emerges in this curve. This periodicity can be related to a process of successive coupling and decoupling of the interface. The partial coupling permits some loading phases (gel velocity negative) followed by unloading phases (gel velocity positive). The unloading phases last 0.2 to 0.4 s and are related to a slow slip of the gel with respect to the sandpaper. In the same time window, we measured all the depinning events and their locations on the 4.5×5 cm2 surface area. A total of 660 events could be detected. An amplitude was attributed to each of them by measuring the peak value of the particle velocity (value at black point in fig. 2(a)) and subtracting the average velocity at the time of the event. We detected amplitudes going from 8.3×10−4 m/s to 6.5×10−2 m/s. Examination of the locations of the events in space and time show that some zones of the interface are more active than others but there is no evidence of a migration in relation with slow slip. We then studied the global temporal behavior of depinning. The black curve in fig. 3 is the emission rate due to depinning, smoothed with a 30ms time window. The peaks of this curve correspond to periods of more frequent occurrences of large depinning events. Figure 3 shows that these intensive depinning periods correlate with the phases of slow slip of the gel. Qualitatively, this observation is comparable to the statistical description of friction developed in [15], that links the slip periods of stick-slip friction to a massive failure of elastic contacts. Furthermore, even though there is a correlation between the velocity of the gel and the depinning activity, one can note that this correlation is not complete. Almost every phase of slow-slip (peaks of red curve) occurs together with a depinning crisis (peaks of black curve), but the amplitude of the depinning crisis is not directly linked to the
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Permeability and pressure measurements in Lesser Antilles submarine slides: Evidence for pressure-driven slow-slip failure

Permeability and pressure measurements in Lesser Antilles submarine slides: Evidence for pressure-driven slow-slip failure

The technique of comparing in situ seismic velocities derived from rock physics models with in situ wireline measurements of seismic velocity provides a valuable approach for estimating in situ pore fluid pressure that is consistent with V p /V s analysis. These analyses are not independent as both rely on in situ V p and V s data. Integrating pore pressure results with Mohr circle analysis indicates that near-lithostatic fluid pressures exist in sediments deposited in the Grenada basin at site U1399 and that these sediments require minimal changes to the stress regime to fail. It implies that deepwater sediments may deform not just from an initial sliding process itself, but via post deposition stress changes. Deformed units and seismically transparent zones imaged in seismic data are often used to infer the size and shape of slope failures and associated tsunami risk [e.g., Ward, 2001; Bondevik et al., 2005; Gee et al., 2007]. Caution should be used interpreting the timing and size of individual slide events both in seismic data and sediment core analysis, since deforma- tion in deepwater submarine slides may postdate sliding or initial deposition and may occur incrementally as slow-slip events. Future work integrating permeability/consolidation/velocity measurements with 2-D/3-D pore pressure models and stratigraphic interpretation of shallow sediment will provide greater insight into pore pressure evolution and sediment deformation in this region.
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Intense interface seismicity triggered by a shallow slow slip event in the Central Ecuador subduction zone

Intense interface seismicity triggered by a shallow slow slip event in the Central Ecuador subduction zone

[ 3 ] Since the discovery of SSEs, this proximity between the slow slip processes and earthquake-prone areas has raised the question of their seismic triggering potential [e.g., Dragert et al., 2001; Mazzotti and Adams, 2004]. As a matter of fact, although SSEs should inhibit the seismic rupture where they occur, the stress increment they induce may pro- mote the seismic rupture in the surrounding fault segments when near to failure. The close relationships between SSEs and seismic processes have been evidenced but usually not with classical seismicity: SSEs are often shown to be accom- panied by a peculiar seismic activity, referred to as nonvolcanic tremors (NVTs) [Rogers and Dragert, 2003]. These NVTs clearly differ from the usual seismicity because of their long duration and absence of clear wave arrivals. So far, triggering of large interplate earthquakes by slow slip events has not been observed, although aseismic slip has been proposed to precede the 2011 Tohoku (Japan) earth- quake [Kato et al., 2012]. Concerning the lower magnitude seismicity, earthquakes rate has been shown to clearly increase during the SSEs in only two subduction areas,
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Strain accommodation by slow slip and dyking in a youthful continental rift, East Africa

Strain accommodation by slow slip and dyking in a youthful continental rift, East Africa

sphere during the initial stages of rifting. Here we show that most of the strain during the July–August 2007 seismic crisis in the weakly extended Natron rift, Tanzania, was released aseismically. Deformation was achieved by slow slip on a normal fault that pro- moted subsequent dyke intrusion by stress unclamping. This event provides compelling evidence for strain accommodation by magma intrusion, in addition to slip along normal faults, during the initial stages of continental rifting and before significant crustal thinning. In July–August 2007, a seismo-magmatic crisis in the Natron basin (Fig. 1) was accompanied by the first dyking event ever captured geodetically in a continental rift 4
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Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip

Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip

A remotely triggered slow slip event We also find that the 2016 Pedernales earthquake triggered a shallow slow slip event (SSE) ~100 km south of the seismic rupture (Fig. 2A). The slip took place close to the trench at a depth shallower than 10 km. It had maximum slips of 0.4 to 0.8 m, with equivalent magnitudes of M w 6.7 to 6.8, and was spatially and temporally associated with signif- icant microseismicity (Figs. 2A and 3, E and K). Unlike afterslip patches, which show slip initiating immediately after the mainshock and decelerating through time, slip here shows a progressive acceler- ation before a phase of deceleration, typical of SSEs (9). All the aseismic slip occurred over a 3-week period, ending 25 days after the mainshock. The static Coulomb stress increment induced by the mainshock is on the order of a few kilopascals at the SSE location, consistent with stress perturbation values proposed for triggering or modulating SSEs (10).
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Spatial and temporal evolution of a long term slow slip event: the 2006 Guerrero Slow Slip Event

Spatial and temporal evolution of a long term slow slip event: the 2006 Guerrero Slow Slip Event

6 C O N C L U S I O N S Slow slip events are thought to represent source instabilities at the transition between velocity-weakening and velocity-strengthening portions of the plate (e.g. Liu & Rice 2005). GPS time series can constrain the temporal evolution of the 2006 Guerrero SSE, and our time-dependent inversion reveals the kinematic slip history of this Slow Slip Event. Our results show that the slip evolution during the SSE can be described with a rather simple smooth ramp. The rise-time of this slip is large with respect to the total duration of the rupture process, which means that there is an interaction between large parts of the fault during the dynamic process. This charac- teristic differs from regular earthquake properties. Variations in the direction of displacement observed at the surface provide a strong constraint on the slip propagation velocity. Our results show that a propagation velocity around 0.8 km d −1 explains the observa- tions. This velocity is slower than the velocity observed for lower magnitude Cascadia events. Our results suggest that the extent and propagation of this SSE is controlled by the geometry of the sub- duction.
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The Transient and Intermittent Nature of Slow Slip

The Transient and Intermittent Nature of Slow Slip

AGU Advances 10.1029/2019AV000126 This exciting time of discovery after discovery has, however, created a dense lexicon of aseismic slip, whose litany of acronyms is impenetrable to the uninitiated. Both networks of permanent GPS stations and time series of InSAR data capture aseismic slip with an apparent constant rate (e.g., Harris, 2017; Jolivet et al., 2015; Loveless & Meade, 2011; Metois et al., 2012), postseismic afterslip (e.g., Lin et al., 2013; Perfettini et al., 2010), or episodic slow slip events (e.g., Radiguet et al., 2012; Rogers & Dragert, 2003), sometimes even with qualifiers like “long term” or “short term” that refer to different time scales that vary from region to region. We can also include low fault coupling at subduction zones (e.g., Metois et al., 2016) or continental faults (e.g., Jolivet et al., 2015) as another form of slow slip with yet another name. Seismology has also contributed to the confusion with its own jargon of indirect manifestations of slow slip, including sequences of repeating earthquakes (i.e., seismic ruptures embedded in a predominantly aseismic fault segment; e.g., Nadeau & McEvilly, 1999; Uchida et al., 2016), or the unique seismic signals that accompany slow slip, whether it be emergent tectonic tremors (e.g., Obara, 2002; Rogers & Dragert, 2003), impulsive low-frequency earthquakes (Shelly et al., 2007), or even very low frequency earthquakes (Ito et al., 2007).
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Inherited state of stress as a key factor controlling slip and slip mode: inference from the study of a slow slip event in the Longitudinal Valley, Taiwan

Inherited state of stress as a key factor controlling slip and slip mode: inference from the study of a slow slip event in the Longitudinal Valley, Taiwan

rectangle outlines the SSE rupture area and black star denotes the Chengkung earthquake epicenter. Black curves give the contour lines of the coseismic (b,c) and postseismic (d) slip distribution models (in meter). Cumulative slip along the long-term rake for the A4 area and for the column c12 (see (a)) are given respectively in (e) and (f). For area A4,

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The predictable chaos of slow earthquakes

The predictable chaos of slow earthquakes

Recent laboratory experiments have shown that both slow and fast ruptures are preceded by crackling that can be detected and used to forecast the time of failure, implying that the stick-slip behavior observed in these experiments is governed by some deterministic dynamics (16). In nature, a possible chaotic behavior has been inferred in the particular case of low-frequency earthquakes (17), a class of small slow earthquakes that can be detected and characterized with seismology. Geodetic position time series capture the whole deformation independently of radiated seismic waves and can thus give a more comprehensive view of fault slip, in particular during slow earthquakes. Here, we focus on slow slip events (SSEs) imaged from geodetic time series. SSEs are a stick-slip phenomenon, which presents a recurrence time much shorter than that of typical earth- quakes, of the order of months or years instead of decades or centuries. They have been documented along major subduction megathrusts (15), reaching moment magnitudes [M w ] comparable to that of large earthquakes [M w > 7]. SSEs are notably similar to regular earth- quakes. They evolve into large pulse-like ruptures (18). They follow similar scaling laws and exhibit systematic along-strike segmentation (18–19). These characteristics make them a most suitable system to study the dynamics of frictional sliding at scale of the order of hundreds or thousands of kilometers. Our goal is to characterize whether the observed slip time series irregular behavior is emerging from an underlying deterministic dynamics or from a stochastic nature of the source.
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Le slow tourism à Lausanne et ses impacts environnementaux sur la destination

Le slow tourism à Lausanne et ses impacts environnementaux sur la destination

4.4 Synthèse et analyse de la première partie de l’enquête quantitative Tout d’abord, le slow tourism est une forme de tourisme récente et complexe et cela se ressent dans les réponses. De fait, seule une faible majorité (53.7%) a répondu connaître le slow tourism. Sachant que ce concept est nouveau et qu’il peut être confondu avec d’autres formes de tourisme proches, cette majorité démontre malgré tout un intérêt pour le développement de ce tourisme. Cela dit, c’est principalement à l’école que ces personnes en ont entendu parler, ce qui limite le public cible auprès duquel ce thème est communiqué. Certes les réseaux sociaux ainsi que les médias traditionnels ont contribué à l’expansion de ce thème mais de façon restreinte. Cela est peut-être dû au fait que chaque personne choisit ce qu’elle a envie de voir ou lire et donc ne s’arrête pas forcément sur ce thème. À l’école, au contraire, ce thème fait peut-être partie du programme et il est alors obligatoirement évoqué. Ensuite, à travers les questions concernant la pratique du slow tourism, il est, une fois encore, mis en évidence que cette forme de tourisme n’est pas encore très développée. Effectivement, seulement 16 personnes sur les 95 de Suisse romande interrogées ont déjà pratiqué ce tourisme. Ce qui ressort de façon positive en revanche est que 86 personnes seraient intéressées à le pratiquer pour la première fois ou à nouveau. De plus, il est également intéressant de mentionner qu’une des 16 personnes ayant décrit leur expérience, pense avoir pratiqué du slow tourism sans vraiment le savoir. Cela indique que la façon dont il faut pratiquer cette forme de tourisme n’est pas forcément très éunivoque. Enfin, en ce qui concerne les différentes catégories pour la pratique d’un tourisme lent, le transport est celle qui ressort comme la moins attirante. Cela est peut-être dû au fait que pratiquer du slow tourism au niveau du transport, implique l’utilisation de la mobilité douce ou des transports en commun et limite alors les destinations dans lesquelles ces personnes pourraient se rendre.
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Slow-wave sleep : generation and propagation of slow waves, role in long-term plasticity and gating

Slow-wave sleep : generation and propagation of slow waves, role in long-term plasticity and gating

1.2.4.4 Spindle oscillation Sleep spindle oscillations consist in a group of rhythmic waves characterized by a progressively increasing, then gradually decreasing field potentials amplitude (waxing-and- waning) of 7-15 Hz which last 1-3 sec and recur every 5-15 sec. Spindles were first observed by Berger in 1933 (Berger, 1933) but their name “spindle” was given two years later (Loomis et al., 1935). In vivo, spindle oscillations are typically observed during light stages of sleep or during active phases of slow-wave sleep oscillations (Fig. I-3 c). In cats, the maximal occurrence of sleep spindle was found in motor, somatosensory, and to a lesser extent in associative cortical areas (Morison and Dempsey, 1942). In humans, spindles are rather fast (13–15 Hz) in centroparietal regions while they appear with slightly slower frequencies (11–13 Hz) in frontal regions (Jankel and Niedermeyer, 1985; De Gennaro and Ferrara, 2003; Andrillon et al., 2011). Fast centroparietal spindles occur mainly at the active state onset while slow frontal spindles occur later during active state often at the transition toward silent state (Molle et al., 2011). The thalamus is separated in a core pathway in which thalamocortical cells projects focally to cortical layer IV, and in a matrix pathway that have diffuse projections to layer I (Jones, 2001, 2002).The difference in spindle frequency was previously attributed to intrinsic properties of the thalamic reticular nucleus with longer hyperpolarisation leading to longer spike-bursts and a lower frequency of spindles (Steriade and Amzica, 1998). However, a recent modelling study suggested that spindles are initiated in the core pathway, but the widespread cortical synchronization was achieved by the matrix pathway (Bonjean et al., 2012).
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Intrinsic coupling between gamma oscillations, neuronal discharges, and slow cortical oscillations during human slow-wave sleep.: Coupling of slow waves, gamma activity, and MUA

Intrinsic coupling between gamma oscillations, neuronal discharges, and slow cortical oscillations during human slow-wave sleep.: Coupling of slow waves, gamma activity, and MUA

Le Van Quyen et al. (2010) extend this line of research by examining the intensity and timing of gamma events with respect to sleep stages and slow oscillations in hu- mans. Scalp EEG was simultaneously ac- quired with local field potentials (LFPs) and multiunit activity (MUA) recordings via macroelectrodes and microelectrodes implanted in epileptic patients. Gamma oscillations (40 –120 Hz) appeared across all sleep stages in the human cortex, yet, surprisingly, they occurred far more fre- quently during SWS than during quiet wakefulness or rapid eye movement (REM) sleep [Le Van Quyen et al. (2010), their Fig. 2A]. Parahippocampal gyrus ap- peared to be the origin for many of these events, although they were observed to a lesser extent across all other implanted ar- eas, including cingulate, occipital, orbito- frontal, and superior temporal cortices, as well as supplementary motor area [Le Van
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On ACK Filtering on a Slow Reverse Channel

On ACK Filtering on a Slow Reverse Channel

101 - 54602 Villers lès Nancy Cedex France Unité de recherche INRIA Rennes : IRISA, Campus universitaire de Beaulieu - 35042 Rennes Cedex France Unité de recherche INRIA Rhône-Alpes : 65[r]

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Slow colloidal aggregation and membrane fouling

Slow colloidal aggregation and membrane fouling

2.2. Critical flux As mentioned earlier, the critical flux is often defined as corre- sponding to the conditions for which the critical concentration has been reached in the membrane boundary layer [17]. As shown in Harmant and Aimar [18], this can be viewed as the flux for which the drag force is larger than the thermodynamic forces which keeps the particles apart. Several experimental studies support this def- inition. We assume that whenever the pressure is such that the flux goes beyond the critical flux, then the solutes/suspended par- ticles form gel beads or aggregates. Such enlarged particles have a lower diffusion coefficient than the original, dispersed ones and they more easily deposit on the membrane. In existing models, this mechanism is generally assumed to be limited by the rate of convec- tion of aggregates to the surface by the filtration flux. This approach predicts a return to a steady state after a rapid flux decline, but it does not predict any further slow flux decline.
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Mid-Miocene strike-slip in continental Greece

Mid-Miocene strike-slip in continental Greece

Classical view of the geodynamic evolution of Greece:1/ Classical back-arc extension with N150 normal faults 2/ followed by mainly N50 dextral strike-slip faults (Gulf of Evvia and Corinth) since 5 Ma marking the impact of the NAF in the tectonic system

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Origins of oblique-slip faulting during caldera subsidence

Origins of oblique-slip faulting during caldera subsidence

[ 87 ] Although we limited our models to T/D < 1, their results allow us to make some inferences about how oblique-slip faulting may manifest at depth in cases where T/D > 1, such as at Dolomieu caldera (T/D ~ 2.0) [Michon et al., 2009]. Our T/D = 0.8 models show that oblique-slip faults localize between the reverse and normal ring faults as a result of displacement along either or both of these structures (e.g., Figures 10c and 11c). Past modeling studies [e.g., Holohan et al., 2011; Roche et al., 2000] show that T/D > 1 leads to a vertical succession of such normal and reverse ring faults. Hence, oblique-slip faults are inferred to form not only near the surface but also at depth, wherever suf ficient horizontal inward displacement occurs along in- ward- or outward-dipping ring faults. This inference may help explain the abundance of oblique-slip earthquake source mechanisms observed at depth during the 2007 Dolomieu collapse [Massin et al., 2011] (Figure 1c).
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First-Principles Study of Secondary Slip in Zirconium

First-Principles Study of Secondary Slip in Zirconium

Thus far, cross slip has mostly been studied in face- centered cubic (fcc) metals for the conventional pla- nar dissociated 1/2h110i{111} dislocations. Elastic- ity models [2, 3] confirmed by atomic-scale simulations [4, 5] showed that the dominant cross-slip mechanism in- volves a local constriction of the dislocation in its ini- tial glide plane followed by redissociation in the cross- slip plane (Friedel-Escaig mechanism). Another mech- anism, which occurs under higher stresses met, for in- stance, in nanocrystalline plasticity [6], involves the suc- cessive change of glide plane of both partial dislocations [7]. Mechanisms involving a metastable configuration of the screw dislocation spread over several planes are also possible, as found in iridium [8].
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Localized rotating convection with no-slip boundary conditions

Localized rotating convection with no-slip boundary conditions

We have also computed the leading eigenvalues along each of the odd and even convecton branches in Fig. 5 and found that convectons on the segments with positive slope are stable with respect to two-dimensional perturbations of like parity. This is not the case for stress-free boundary conditions since the primary steady state bifurcation is preceded, for these boundary conditions and parameter values, by several Hopf bifurcations from the conduction state. The resulting unstable eigenvalues are inherited by both periodic and localized convection, rendering all stationary solutions of either type unstable, at least at small amplitude. Thus, no-slip boundary conditions stabilize localized convection. These stability assignments follow those for the cubic-quintic Swift-Hohenberg equation, an equation that shares the symmetry R z with the present problem, 12 and come about in
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Slow-Wave-Based Nanomagnonic Diode

Slow-Wave-Based Nanomagnonic Diode

3 Institut Jean Lamour, Université de Lorraine, UMR 7198, CNRS, F-54000 Nancy, France (Received 17 December 2019; revised 17 July 2020; accepted 17 July 2020; published 18 August 2020) Spin waves, the collective excitations of the magnetic order parameter, and magnons, the associated quasiparticles, are envisioned as possible data carriers in future wave-based computing architectures. On the road toward spin-wave computing, the development of a diodelike device capable of transmitting spin waves in only one direction, thus allowing controlled signal routing, is an essential step. Here we report on the design and experimental realization of a microstructured magnonic diode in a ferromagnetic bilayer system. Effective unidirectional propagation of spin waves is achieved by taking advantage of nonreciprocities produced by dynamic dipolar interactions in transversally magnetized media, which lack symmetry about their horizontal midplane. More specifically, dipolar-induced nonreciprocities are used to engineer the spin-wave dispersion relation of the bilayer system so that the group velocity is reduced to very low values for one direction of propagation and not for the other, thus producing unidirectional slow spin waves. Brillouin light scattering and propagating-spin-wave spectroscopy are used to demonstrate the diodelike behavior of the device, the composition of which is first optimized through micromagnetic simulations.
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