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Mizoguchi, K.
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Mizoguchi, K.
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- PublicationRestrictedFault lubrication during earthquakes(2011-03-24)
; ; ; ; ; ; ; ; ; ;Di Toro, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Han, R.; Korea Inst Geosci & Mineral Resources, Taejon 305350, South Korea ;Hirose, T.; JAMSTEC, Kochi Inst Core Sample Res, Kochi 7838502, Japan ;De Paola, N.; Univ Durham, Dept Earth Sci, Durham DH1 3LE, England ;Nielsen, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mizoguchi, K.; Cent Res Inst Elect Power Ind, Civil Engn Res Lab, Chiba 2701194, Japan ;Ferri, F.; Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy ;Cocco, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Shimamoto, T.; China Earthquake Adm, Inst Geol, Beijing 100029, Peoples R China; ; ; ; ; ; ; ; The determination of rock friction at seismic slip rates (about 1 m s(-1)) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip(1). Given the difficulty in determining friction by seismological methods(1), elucidating constraints are derived from experimental studies(2-9). Here we review a large set of published and unpublished experiments (similar to 300) performed in rotary shear apparatus at slip rates of 0.1-2.6 ms(-1). The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built(4-6), quartz-built(3) and carbonate-built(7,8)) rocks and non-cohesive rocks (clay-rich(9), anhydrite, gypsum and dolomite(10) gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger(11,12) a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates(13,14) suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7-15 km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved.253 47