DOI: 10.1038/NGEO2436
论文题名: Phase transformation and nanometric flow cause extreme weakening during fault slip
作者: Green H.W. ; Shi F. ; Bozhilov K. ; Xia G. ; Reches Z.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2015
卷: 8, 期: 6 起始页码: 448
结束页码: 489
语种: 英语
Scopus关键词: aureole
; earthquake intensity
; extreme event
; fault slip
; faulting
; grain boundary
; instability
; San Andreas Fault
; shear stress
; temperature gradient
英文摘要: Earthquake instability requires fault weakening during slip. The mechanism of this weakening is central to understanding earthquake sliding and, in many cases, has been attributed to fluids. It is also unclear why major faults such as the San Andreas Fault do not exhibit significant thermal anomalies due to shear heating during sliding and whether or not fault rocks that have been melted-pseudotachylytes-are rare. High-speed friction experiments on a wide variety of rock types have shown that they all exhibit extremeweakening and that the sliding surface is nanometric and contains phases not present at the start. Here we use electron microscopy to examine these two key observations in high-speed friction experiments and compare them with high-pressure faulting experiments. We show that phase transformations occur in both cases and that they are associated with profound weakening. However, fluid is not necessary for such weakening; the nanometric fault filling is inherently weak at seismic sliding rates and it flows by grain boundary sliding. These observations suggest that pseudotachylytes are rare in nature because shear-heating-induced endothermic reactions in fault zones prevent temperature rise to melting. Microstructures preserved in the Punchbowl Fault, an ancestral branch of the San Andreas Fault, suggest similar processes during natural faulting and er an explanation for the lack of a thermal aureole around major faults. © 2015 Macmillan Publishers Limited. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106167
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: Department of Earth Sciences, University of California, Riverside, CA, United States; Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside, CA, United States; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, China; School of Geology and Geophysics, University of Oklahoma, Norman, OK, United States; School of Earth Sciences, University of Queensland, Queensland, Australia
Recommended Citation:
Green H.W.,Shi F.,Bozhilov K.,et al. Phase transformation and nanometric flow cause extreme weakening during fault slip[J]. Nature Geoscience,2015-01-01,8(6)