Fault Weakening During Short Seismic Slip Pulse Experiments: The Role of Pressurized Water and Implications for Induced Earthquakes in the Groningen Gas Field

High-velocity friction experiments on simulated fault gouges sheared at high normal stress and to low displacement are particularly relevant to induced seismicity, which is becoming an important topic in fault mechanics. Using a new, improved set-up, which allows simulation of fault stress and fluid pressure ((Formula presented.)) conditions...

Effects of heterogeneous gouge segments on the slip behavior of experimental faults at dm scale

Frictional heterogeneity within fault zones is one of the factors proposed to explain the spectrum of slow, intermediate, and fast slip behaviors exhibited by faults in nature. Numerical modeling shows how even a simplified model setup incorporating sliding on a velocity-weakening (VW) patch surrounded by velocity-strengthening (VS) material can...

Seismic slip-pulse experiments simulate induced earthquake rupture in the Groningen Gas field

Nucleation of Stick-Slip Instability Within a Large-Scale Experimental Fault Effects of Stress Heterogeneities Due to Loading and Gouge Layer Compaction

Geodetic observations and large‐scale laboratory experiments show that seismic instability is preceded by slow slip within a finite nucleation zone. In laboratory experiments rupture nucleation is studied mostly using bare (rock) interfaces, whereas upper crustal faults are typically filled with gouge. To investigate effects of gouge on rupture...

Applied stress reduces swelling of coal induced by adsorption of water

This paper investigates whether or not applied stress reduces swelling of coal upon water adsorption, and, if so, what mechanisms are responsible. With this aim, thermodynamic models were developed addressing the effect of a general applied stress on water adsorption capacity and associated swelling behaviour of coal matrix material, assuming...

Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10−8–10−4 ms−1) or in the high velocity regime (0.01–1 m s−1). Here, we report on the evolution of friction...

Coupling of swelling, internal stress evolution, and diffusion in coal matrix material during exposure to methane

We construct theoretical models for time-dependent swelling of coal matrix material upon adsorption of a single gas, taking into account a coupling between stress, strain, chemical potential, and diffusion. Two models are developed. The first (model A) corresponds to diffusion and hence swelling rates being controlled by the jump frequency of...

Compaction creep of quartz sand at 400-600°C: Experimental evidence for dissolution-controlled pressure solution

Intergranular pressure solution (IPS) is an important compaction and deformation mechanism in quartzose rocks, but the kinetics and rate-controlling process remain unclear. The aim of the present study is to test microphysical models for compaction creep by IPS against isostatic hot pressing experiments performed on quartz sand under conditions...

Fluid-assisted healing processes in gouge-bearing faults Insights from experiments on a rock analogue system

On the basis of both experimental and field studies, solution transfer processes are expected to be important in contributing to fault strength recovery (healing) under the hydrothermal conditions prevailing in large parts of the seismogenic zone. However, most experimental work on healing effects in faults has been done using quartzo...

Frictional-viscous flow of phyllosilicate-bearing fault rock: Microphysical model and implications for crustal strength profiles

It is widely believed that around the brittle-ductile transition, crustal faults can be significantly weaker than predicted by conventional two-mechanism brittle-ductile strength envelopes. Factors contributing to this weakness include the polyphase nature of natural rocks, foliation development, and the action of fluid-assisted processes such...