Abstract Classical rate‐and‐state friction (RSF) laws are widely applied in modeling earthquake dynamics but generally using empirically determined parameters with little or no knowledge of, quantitative account for, the controlling physical mechanisms. Here a mechanism‐based microphysical model is developed for describing frictional behavior of carbonate fault gouge, assuming that seen lab experiments controlled by competing processes rate‐strengthening intergranular sliding versus contact...

Abstract Fault slip and healing history may crucially affect the fault seismogenic potential in earthquake nucleation regime. Here we report direct shear friction tests on simulated gouges derived from a carbonate breccia, clay/carbonate fault‐core gouge, retrieved surface exposure of Longmenshan Zone (LFZ) which hosted 2008 Wenchuan earthquake. The experiments were conducted under dry hydrothermal conditions, at temperatures up to 140°C, an effective normal stress 50 MPa, involved...

Abstract Rate‐and‐state friction (RSF) laws are extensively applied in fault mechanics but have a largely empirical basis reflecting only limited understanding of the underlying physical mechanisms. We recently proposed microphysical model describing frictional behavior granular gouge undergoing deformation terms flow accompanied by thermally activated creep and intergranular sliding at grain contacts. Numerical solutions reproduced typical experimental results well. Here we extend our to...

Rate-and-state friction (RSF) is commonly used for the characterisation of laboratory experiments, such as velocity-step tests. However, RSF framework provides little physical basis extrapolation these results to scales and conditions natural fault systems, so open questions remain regarding applicability experimentally obtained parameters predicting seismic cycle transients. As an alternative classical RSF, microphysics-based models offer means interpreting field observations, but are...

Abstract We investigated the frictional properties of carbonate‐rich gouge layers at a slip rate 1.3 m/s, under dry and water‐saturated conditions, while monitoring temperature different locations on one gouge‐host rock interfaces. All experiments showed peak strength 0.4–0.7, followed by strong weakening to steady state values 0.1–0.3. Experiments which used pore fluid with constant drainage path atmosphere development plateau beyond 100°C, contemporaneous dynamic consistent thermodynamic...

Abstract Understanding the motion of particles in very dense granular flows is crucial for comprehending dynamics many geological phenomena, and advancing our knowledge material physics. We conduct transparent ring shear experiments to directly observe under relatively high‐pressure conditions, find that velocity non‐linearly decays, forming an approximately 7‐particle‐diameter‐thick localized band. A fitting curve underlying non‐local physics can be used well predict profile geometries are...

Abstract The slip style of continental midcrustal shear zones plays a crucial role in determining the seismogenic potential faults, but it remains poorly understood because geological observations that can be directly tied to seismic behavior are scarce. We describe frictional-viscous Red River fault, China, which consists two segments with distinct behaviors and fluid availabilities. northern segment hosts moderate large earthquakes, fault is localized into mylonitized...

Summary Faults exhibit dynamic weakening during large displacements (>1 m) at seismic slip velocities (>0.1 m/s), but the role of this in small-displacement induced earthquakes (M 3–4), such as those Groningen Gas Field (the Netherlands), remains unclear. We conducted slip-pulse experiments on Slochteren sandstone gouges (SSG) using a rotary-shear apparatus to investigate their behavior. Pre-sheared gouge layers, confined between ∼1.5 mm thick host blocks, were subjected pulses...

Laboratory studies have demonstrated that faults undergo dynamic weakening during large displacements (>1 m) at seismic slip velocities (>0.1 m/s). However, the role of this in small-displacement induced earthquakes (M 3–4), such as those Groningen Gas Field (the Netherlands), remains unclear. To address this, we conducted slip-pulse experiments on Slochteren sandstone gouges (SSG), derived from gas reservoir, using a rotary-shear apparatus to provide decimeter-scale...

We report variations in the mineralogical, geochemical, and isotopic ( δ 13 C, 18 O) composition of fault rocks sampled transects across Zhaojiagou Pingxi exposures Wenchuan Earthquake or Longmenshan Fault Zone, where gouge‐rich core principal slip surface cuts through carbonate‐rich strata. Pervasive fluid infiltration was found to modify mineralogical geochemical architecture zones studied. Enrichment/depletion patterns, element partitioning, a very large implied volume loss are quite...

Abstract A variety of mechanisms have been proposed to explain how a fault might deform relatively slowly, rather than manifesting as earthquakes. Several rely on the frictional properties interface. In this study I analyze slip stability fluid‐infiltrated in framework microphysically‐based friction model, which has shear zone porosity its state variable. Linear analysis incorporating evolution fluid pressure, gives critical stiffness ( ) and frequency function normalized dilatancy...

Abstract We determined the internal structure and mineral composition of Yingxiu‐Beichuan fault zone at Zhaojiagou exposure measured frictional transport properties rocks collected to gain a better understanding dynamic weakening mechanisms during seismic motion. This is major in Longmenshan system that caused 2008 Wenchuan earthquake. The studied located midway along surface rupture, close where largest coseismic displacement occurred. High‐velocity friction experiments reveal exponential...

Since the late 1990s, eight localities in volcanic shale-rich lacustrine deposits of Middle Jurassic through Early Cretaceous age northern China (western Liaoning Province, Hebei and southern Inner Mongolia) have yielded thousands exceptionally well-preserved salamander specimens. With 10 species published several new taxa yet to be named described, fossil samples from represent most species-diverse, individually abundant, exquisitely preserved assemblage known Mesozoic Era. The...

Major earthquakes frequently nucleate near the base of seismogenic zone, close to brittle-ductile transition. Fault zone rupture at greater depths is inhibited by ductile flow rock. However, microphysical mechanisms responsible for transition from brittle/frictional behaviour shallower remain unclear. Here we show that flow-to-friction in experimentally simulated calcite faults characterized a dislocation and diffusion creep dilatant deformation, involving incompletely accommodated grain...

Abstract Fossils are indispensible in understanding the evolutionary origins of modern fauna. Crown-group spadefoot toads (Anura: Pelobatoidea) best-known fossorial frog clade to inhabit arid environments, with species utilizing a characteristic bony spade on their foot for burrowing. Endemic Northern Hemisphere, they distributed across Holarctic except East Asia. Here we report rare fossil crown-group toad from late Paleocene Mongolia. The phylogenetic analysis using both morphological and...

This paper presents a novel measuring method based on the Hilbert filtering for digital monitoring of single-phase ac frequency, phase, and reactive power. According to this method, sampled voltage signal passes pair filters. Then, frequency phase can be obtained by detection phase-locked loop algorithm. Additionally, current also makes its shift other filter. The output is multiplied one phase-shifted signals, power acquired from dc component product. Because type infinite impulse response...

As a classic unbalanced load, the traction engines of electric railways result in negative-sequence currents(NSC) power systems, which cannot be ignored most cases. SVC is considered as an effective method to reduce or even eliminate NSC, well some other quality problems, such reactive compensation. Calculation formulae NSC two kinds transformers are formed firstly this paper. Then mechanism compensation by discussed. Simulations PSCAD system followed. The results show that efficient compensate NSC.