Does the direct effect of friction increase continuously with absolute temperature?

Area of Science:

• Geophysics
• Rock Mechanics
• Seismology

Background:

• Constitutive models of fault friction are crucial for physics-based seismic simulations.
• The widely adopted framework assumes a thermally activated process governed by an Arrhenius law, predicting temperature-dependent friction.
• This classical view suggests the direct effect of friction increases with absolute temperature.

Purpose of the Study:

• To experimentally test the temperature dependence of the direct effect in fault friction.
• To investigate the relationship between friction, temperature, and deformation mechanisms in rocks.
• To challenge the classical Arrhenius law-based model for fault friction.

Main Methods:

• Analysis of comprehensive laboratory data under diverse hydrothermal, barometric, and lithological conditions.
• Examination of fault friction behavior across varying temperatures and pressures.
• Identification of distinct deformation mechanisms associated with brittle and semi-brittle transitions.

Main Results:

• The direct effect of friction for a given deformation mechanism is largely temperature-independent.
• Incremental shifts in the direct effect correlate with the brittle to semi-brittle transition.
• Distinct deformation mechanisms operate across this transition, influencing frictional behavior.

Conclusions:

• The classical model of thermally activated friction (Arrhenius law) is challenged by experimental evidence.
• Fault friction is primarily governed by the operating deformation mechanisms rather than absolute temperature.
• Realistic constitutive laws for lithospheric rock failure must integrate multiple deformation mechanisms active in fault zones.