Fault lubrication and earthquake propagation in thermally unstable rocks

被引:147
作者
De Paola, Nicola [1 ]
Hirose, Takehiro [2 ]
Mitchell, Tom [3 ]
Di Toro, Giulio [4 ,5 ]
Viti, Cecilia [6 ]
Shimamoto, Toshihiko [7 ]
机构
[1] Univ Durham, Dept Earth Sci, Rock Mech Lab, Durham DH1 3LE, England
[2] Japan Agcy Marine Earth Sci & Technol JAMSTEC, Kochi Inst Core Sample Res, Kochi 7838502, Japan
[3] Ruhr Univ Bochum, Inst Geol Mineral & Geophys, Expt Geophys Lab, D-44780 Bochum, Germany
[4] Ist Nazl Geofis & Vulcanol, I-00143 Rome, Italy
[5] Univ Padua, Dipartimento Geosci, I-35137 Padua, Italy
[6] Univ Siena, Dipartimento Sci Terra, I-53100 Siena, Italy
[7] Hiroshima Univ, Grad Sch Sci, Dept Earth & Planetary Syst Sci, Higashihiroshima 7398526, Japan
基金
欧洲研究理事会;
关键词
FRICTION; PRESSURE; RATES;
D O I
10.1130/G31398.1
中图分类号
P5 [地质学];
学科分类号
0709 ; 081803 ;
摘要
Experiments performed on dolomite or Mg-calcite gouges at seismic slip rates (v > 1 m/s) and displacements (d > 1 m) show that the frictional coefficient mu decays exponentially from peak values (m(p) approximate to 0.8, in the Byerlee's range), to extremely low steady-state values (mu(ss) approximate to 0.1), attained over a weakening distance D-w. Microstructural observations show that discontinuous patches of nanoparticles of dolomite and its decomposition products (periclase and lime or portlandite) were produced in the slip zone during the transient stage (d < D-w). These observations, integrated with CO2 emissions data recorded during the experiments, suggest that particle interaction in the slip zone produces flash temperatures that are large enough to activate chemical and physical processes, e. g., decarbonation reactions (T = 550 degrees C). During steady state (d >= D-w), shear strength is very low and not dependent upon normal stresses, suggesting that pressurized fluids (CO2) may have been temporarily trapped within the slip zone. At this stage a continuous layer of nanoparticles is developed in the slip zone. For d >> D-w, a slight but abrupt increase in shear strength is observed and interpreted as due to fluids escaping the slip zone. At this stage, dynamic weakening appears to be controlled by velocity dependent properties of nanoparticles developed in the slip zone. Experimentally derived seismic source parameter W-b (i.e., breakdown work, the energy that controls the dynamics of a propagating fracture) (1) matches W-b values obtained from seismological data of the A. D. 1997 M6 Colfiorito (Italy) earthquakes, which nucleated in the same type of rocks tested in this study, and (2) suggests similar earthquake-scaling relationships, as inferred from existing seismological data sets. We conclude that dynamic weakening of experimental faults is controlled by multiple slip weakening mechanisms, which are activated or inhibited by physicochemical reactions in the slip zone.
引用
收藏
页码:35 / 38
页数:4
相关论文
共 21 条
  • [1] Constitutive relationships and physical basis of fault strength due to flash heating
    Beeler, N. M.
    Tullis, T. E.
    Goldsby, D. L.
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2008, 113 (B1)
  • [2] High-velocity frictional properties of a clay-bearing fault gouge and implications for earthquake mechanics
    Brantut, N.
    Schubnel, A.
    Rouzaud, J. -N.
    Brunet, F.
    Shimamoto, T.
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2008, 113 (B10)
  • [3] Elastohydrodynamic lubrication of faults
    Brodsky, EE
    Kanamori, H
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2001, 106 (B8) : 16357 - 16374
  • [4] Fault zone architecture and deformation processes within evaporitic rocks in the upper crust
    De Paola, N.
    Collettini, C.
    Faulkner, D. R.
    Trippetta, F.
    [J]. TECTONICS, 2008, 27 (04)
  • [5] Natural and experimental evidence of melt lubrication of faults during earthquakes
    Di Toro, G
    Hirose, T
    Nielsen, S
    Pennacchioni, G
    Shimamoto, T
    [J]. SCIENCE, 2006, 311 (5761) : 647 - 649
  • [6] Friction falls towards zero in quartz rock as slip velocity approaches seismic rates
    Di Toro, G
    Goldsby, DL
    Tullis, TE
    [J]. NATURE, 2004, 427 (6973) : 436 - 439
  • [7] Low frictional strength of quartz rocks at subseismic slip rates
    Goldsby, DL
    Tullis, TE
    [J]. GEOPHYSICAL RESEARCH LETTERS, 2002, 29 (17)
  • [8] Ultralow friction of carbonate faults caused by thermal decomposition
    Han, Raehee
    Shimamoto, Toshihiko
    Hirose, Takehiro
    Ree, Jin-Han
    Ando, Jun-ichi
    [J]. SCIENCE, 2007, 316 (5826) : 878 - 881
  • [9] Strong velocity weakening and powder lubrication of simulated carbonate faults at seismic slip rates
    Han, Raehee
    Hirose, Takehiro
    Shimamoto, Toshihiko
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2010, 115
  • [10] Growth of molten zone as a mechanism of slip weakening of simulated faults in gabbro during frictional melting
    Hirose, T
    Shimamoto, T
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2005, 110 (B5) : 1 - 18