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Laboratory analysis of restrenghtening on simulated faults

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dc.contributor.advisor Chris Marone. en_US
dc.contributor.author Karner, Stephen L. (Stephen Leslie), 1966- en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences. en_US
dc.date.accessioned 2005-09-27T19:36:22Z
dc.date.available 2005-09-27T19:36:22Z
dc.date.copyright 1999 en_US
dc.date.issued 1999 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/8974
dc.description Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1999. en_US
dc.description Includes bibliographical references (p. 105-118). en_US
dc.description.abstract Seismic data show that stress drop increases with the logarithm of earthquake recurrence interval (1-5 MPa per decade time). If stress drop is taken as a proxy for fault strength, then the data suggest that faults restrengthen during the quiescent period of the earthquake cycle. Seismic surveys across natural faults show that seismic velocities increase with elapsed time after an earthquake. These data also indicate that faults lithify and heal during the interseismic period. Hence, this thesis is centered on laboratory research designed to investigate fault restrengthening. Experiments have been conducted to study the factors that effect stick-slip behavior of bare rock surfaces, and healing of simulated fault gouge under a range of physico-chemical conditions. We have performed experiments to investigate the repetitive stick-slip behavior of initially bare granite surfaces (nominal contact area 25 cm2). The tests were conducted in a double-direct shear apparatus at room-temperature and humidity, and normal stress was held constant throughout. Shear was induced by controlling the velocity of the loading piston (0.5-300 µmis). Data from individual stick-slip cycles show that shear stress increases quasi-linearly without considerable displacement across the sliding surface (stick), and sample failure (slip) is accompanied by a rapid stress drop. The amount of stress drop ranges from 0.1 to 3.1 MPa (or 4-49% of the failure strength). Prior to each instability samples exhibit yielding, consistent with previous laboratory observations of premonitory slip. Quasi-periodic instabilities occur repeatedly and we study the effect of loading rate and normal load on stress drop and recurrence interval (the time since the last event). We measure recurrence interval from the time when reloading begins after a slip event to the time that the next instability occurs. At a given loading rate, our data show a positive correlation between stress drop and recurrence interval, indicating healing rates of -3.5 MPa per decade increase in recurrence time. However, the combined data from all velocities show a lower rate, suggesting an apparent healing rate of -0.8 MPa per decade increase in recurrence time. We observe a similar velocity-dependent correlation between the peak shear stress prior to failure ( a measure of the ultimate strength of the material) and recurrence interval. We find a consistent scaling between different loading rates when the stress drop data are compared to the load.point displacement prior to failure ... en_US
dc.description.statementofresponsibility by Stephen L. Karner. en_US
dc.format.extent 241 p. en_US
dc.format.extent 15036969 bytes
dc.format.extent 15036487 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582
dc.subject Earth, Atmospheric, and Planetary Sciences. en_US
dc.title Laboratory analysis of restrenghtening on simulated faults en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences. en_US
dc.identifier.oclc 47079142 en_US


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