Velocity dependence of serpentinite friction promotes aseismic slip on faults

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5707559

Reinen, L A; Weeks, J D; Tullis, T E ^[1]

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1. Brown Univ., Providence, RI (United States). Dept. of Geological Sciences

Serpentinite is common on many crustal faults and it has been suggested that the presence of serpentine on these faults may promote aseismic slip. Consequently, the authors have experimentally measured the frictional constitutive response of both antigorite and lizardite polymorphs of serpentine to step changes in velocity. This was done at room temperature in rotary direct shear; normal stress was 25 MPa, and velocities ranged from 32 mm/yr to 3.2 [times] 10[sup 5] mm/yr. The frictional behavior of both serpentine polymorphs indicates that the presence of either one on a fault would result in aseismic creep in the shallow crust at typical plate motion rates. In contrast to other rock types, such as granite, both serpentinites display velocity-strengthening behavior at slow sliding velocities: below some transitional velocity, the frictional resistance increases with velocity, thus promoting stable aseismic slip. At faster velocities, however, frictional strength has a negative dependence on velocity (velocity weakening), which provides the potential for unstable sliding, leading to earthquakes. The coefficient of friction of the antigorite serpentinite is similar to that of other silicates, while that of the lizardite is much lower. The low frictional strength of lizardite may help explain some geologic observations that serpentine appears quite mobile during deformation in the crust. However, it is the velocity-strengthening behavior observed in both serpentinites at low sliding velocities, and not the frictional strength, that will promote aseismic slip on serpentine-bearing faults at typical rates of plate motion.

• OSTI ID: 5707559
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CONTINENTAL CRUST
CREEP
EARTH CRUST
FRICTION
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
MECHANICAL PROPERTIES
METAMORPHIC ROCKS
MINERALS
ROCKS
SERPENTINE
SERPENTINITES
SILICATE MINERALS
SLIDING FRICTION
SLIP