Search Results - (Author, Cooperation:D. A. Lockner)
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1Latest Papers from Table of Contents or Articles in PressJ. C. Chang ; D. A. Lockner ; Z. Reches
American Association for the Advancement of Science (AAAS)
Published 2012Staff ViewPublication Date: 2012-10-09Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: *Acceleration ; *Earthquakes ; LaboratoriesPublished by: -
2Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2011-03-29Publisher: Nature Publishing Group (NPG)Print ISSN: 0028-0836Electronic ISSN: 1476-4687Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsPublished by: -
3Articles: DFG German National LicensesLockner, D. A. ; Byerlee, J. D. ; Kuksenko, V. ; Ponomarev, A. ; Sidorin, A.
[s.l.] : Nature Publishing Group
Published 1991Staff ViewISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] The failure process in a brittle granite sample can be stabilized by controlling axial stress to maintain a constant rate of acoustic emission. As a result, the post-failure stress curve can be followed quasi-statically, extending to hours the fault growth process which normally would occur ...Type of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesLockner, D. A. ; Johnston, M. J. S. ; Byerlee, J. D.
[s.l.] : Nature Publishing Group
Published 1983Staff ViewISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] Explanations of how earthquake lights might arise have failed to show how large charge densities can be concentrated and sustained in a conductive Earth. A physical model is proposed, based on frictional heating of the fault, that solves this and related ...Type of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesStaff View
ISSN: 1420-9136Keywords: Velocity anomalies ; Microfractures ; Stick-slipSource: Springer Online Journal Archives 1860-2000Topics: GeosciencesPhysicsNotes: Abstract Locations and velocities were calculated for microseisms occurring in samples of rock subjected to triaxial loading and injection of pore fluid. This was accomplished by analyzing arrival times of acoustic emission using an automatic first arrival picker. Apparent velocity anomalies were observed prior to both failure of intact samples and violent slip in samples containing saw cuts. Further analysis revealed that these fluctuations in calculated velocity were not due to changes in the true seismie velocity. Instead, variations in calculated velocity are shown to be related to sampling errors in picking first arrivals. The systematic picking of late first arrivals for small magnitude events was found to be a persistent bias resulting in low calculated velocities. This has encouraged the reexamination of earthquake records to determine how important sampling biases are in contributing to reported velocity anomalies.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1420-9136Keywords: Induced polarization ; earthquakeSource: Springer Online Journal Archives 1860-2000Topics: GeosciencesPhysicsNotes: Abstract Measurements of charge separation in rock during stable and unstable deformation give unexpectedly large decay times of 50 sec. Time-domain induced polarization experiments on wet and dry rocks give similar decay times and suggest that the same decay mechanisms operate in the induced polarization response as in the relaxation of charge generated by mechanical deformation. These large decay times are attributed to electrochemical processes in the rocks, and they require low-frequency relative permittivity to be very large, in excess of 105. One consequence of large permittivity, and therefore long decay times, is that a significant portion of any electrical charge generated during an earthquake can persist for tens or hundreds of seconds. As a result, electrical disturbances associated with earthquakes should be observable for these lengths of time rather than for the milliseconds previously suggested.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 1420-9136Keywords: Shear strength ; temperature ; deformation rateSource: Springer Online Journal Archives 1860-2000Topics: GeosciencesPhysicsNotes: Abstract Layers of artificial granite gouge have been deformed on saw-cut granite surfaces inclined 30° to the sample axes. Samples were deformed at a constant confining pressure of 250 MPa and temperatures of 22 to 845°C. The velocity dependence of the steady-state coefficient of friction (μss) was determined by comparing sliding strengths at different sliding rates. The results of these measurements are consistent with those reported bySolberg andByerlee (1984) at room temperature andStesky (1975) between 300 and 400°C. Stesky found that the slip-rate dependence of (μss) increased above 400°C. In the present study, however, the velocity dependence of (μss) was nearly independent of temperature.Type of Medium: Electronic ResourceURL: