HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Hirose, T. Articles by Shimamoto, T. Search for Related Content GeoRef GeoRef Citation

Slip-Weakening Distance of Faults during Frictional Melting as Inferred from Experimental and Natural Pseudotachylytes

¹ Department of Geology and Mineralogy
Graduate School of Science
Kyoto University
Kyoto 606-8502, Japan

The slip-weakening distance, D_c, over which a fault weakens during seismogenic fault motion, is one of most important parameters controlling fault instability. A paradox over the last decade has been the source of the large difference between laboratory-measured values of D_c using conventional friction experiments (10^–5–10^–3 m) and seismically determined D_c values for natural earthquakes (10^–1–10⁰ m). D_c is a difficult quantity to estimate for natural faults, but this study attempts to determine the order of D_c values for natural faults containing pseudotachylytes based on a comparison between experimental and natural pseudotachylytes. Experiments at a constant slip velocity of 0.85 m/sec and a normal stress of 1.4 MPa on gabbro have revealed that the progressive growth of a molten layer causes marked slip weakening. Slip weakening (a reduction in frictional strength with displacement) and the growth of the molten layer (an increase in the thickness of the molten layer with displacement) are both characterized by exponential changes with nearly the same characteristic distances. The comparison suggests that the order of D_c can be estimated from the relationship between pseudotachylyte thickness along its generation fault and fault displacement. Sibson’s (1975) data from the Outer Hebrides exhibit a similar pseudotachylyte-thickness-versus-fault-displacement curve with a characteristic distance of 0.38 m. This is the same order of magnitude as seismically inferred values of D_c. The effect of frictional melting is a possible solution for the D_c paradox, although it is not the only possible solution, since frictional melting along large faults is rather uncommon.

This article has been cited by other articles:

				C. A. J. Wibberley, G. Yielding, and G. Di Toro Recent advances in the understanding of fault zone internal structure: a review Geological Society, London, Special Publications, January 1, 2008; 299(1): 5 - 33. [Abstract] [Full Text] [PDF]

				R. Han, T. Shimamoto, T. Hirose, J.-H. Ree, and J.-i. Ando Ultralow Friction of Carbonate Faults Caused by Thermal Decomposition Science, May 11, 2007; 316(5826): 878 - 881. [Abstract] [Full Text] [PDF]