Affordable Access

Access to the full text

Is complex fault zone behaviour a reflection of rheological heterogeneity?

Authors
  • Fagereng, Å.
  • Beall, A.
Type
Published Article
Journal
Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences
Publisher
The Royal Society
Publication Date
Feb 01, 2021
Volume
379
Issue
2193
Identifiers
DOI: 10.1098/rsta.2019.0421
PMID: 33517872
PMCID: PMC7898124
Source
PubMed Central
Keywords
Disciplines
  • Research Article
License
Green

Abstract

Fault slip speeds range from steady plate boundary creep through to earthquake slip. Geological descriptions of faults range from localized displacement on one or more discrete planes, through to distributed shearing flow in tabular zones of finite thickness, indicating a large range of possible strain rates in natural faults. We review geological observations and analyse numerical models of two-phase shear zones to discuss the degree and distribution of fault zone heterogeneity and effects on active fault slip style. There must be certain conditions that produce earthquakes, creep and slip at intermediate velocities. Because intermediate slip styles occur over large ranges in temperature, the controlling conditions must be effects of fault properties and/or other dynamic variables. We suggest that the ratio of bulk driving stress to frictional yield strength, and viscosity contrasts within the fault zone, are critical factors. While earthquake nucleation requires the frictional yield to be reached, steady viscous flow requires conditions far from the frictional yield. Intermediate slip speeds may arise when driving stress is sufficient to nucleate local frictional failure by stress amplification, or local frictional yield is lowered by fluid pressure, but such failure is spatially limited by surrounding shear zone stress heterogeneity. This article is part of a discussion meeting issue ‘Understanding earthquakes using the geological record’.

Report this publication

Statistics

Seen <100 times