Consequences of viscous drag beneath a transform fault

Journal of Geophysical Research
By:  and 



A transform fault is modeled as a vertical cut through an elastic layer (schizosphere) of thickness overlying a viscous substrate (plastosphere). We consider a steady transform motion accommodated in the schizosphere wholly by slip on the fault and in the plastosphere, insofar as possible, by viscous flow. For the case where the viscosity in the plastosphere is strain rate dependent but independent of temperature, the velocity solution in the plastosphere is θ/π, where is the slip rate on the fault in the schizosphere and and θ are the cylindrical coordinates with the origin at the bottom of the fault. The viscous stress is singular at the bottom of the fault ( = 0) and exceeds the brittle (frictional) strength for . Equating the brittle strength to the viscous stress defines the brittle–ductile boundary in the plastosphere as a function of and viscosity. The additional condition that must be small allows the viscosity to be estimated from . For small , the temperature‐independent solution is a valid approximation to the temperature‐dependent solution, and the relation between viscosity and should remain valid. From the temperature‐independent model, we estimate that self‐heating due to dissipation in the plastosphere for reasonable Earth parameters is less than ∼20°C.

Publication type Article
Publication Subtype Journal Article
Title Consequences of viscous drag beneath a transform fault
Series title Journal of Geophysical Research
DOI 10.1029/2001JB000711
Volume 108
Issue B1
Year Published 2003
Language English
Publisher Wiley
Contributing office(s) Earthquake Science Center
Description 2025, 13p.
First page 1
Last page 13
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