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Author Bodin, P. ♦ Brown, S. ♦ Matheson, D.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword GEOSCIENCES ♦ SEISMIC WAVES ♦ EARTHQUAKES ♦ GEOLOGIC FAULTS ♦ EARTH CRUST ♦ SIMULATION ♦ MECHANICAL VIBRATIONS ♦ TRAVELLING WAVES ♦ INTERFACES ♦ SLIP ♦ SEISMIC P WAVES ♦ INSTABILITY ♦ POLYMERS
Abstract We report laboratory observations of interface separation waves during stick slip on a fault in a uniform polymer material. Our observations, made at stress levels expected at midcrustal depths, share many macroscopic properties with ruptures of faults in rocks. We observed a drop in fault-normal stress shortly before the onset of, and during, stick slip at points along the fault during a rupture. We suggest that {ital P} wave energy in front of the propagating rupture tip is responsible for the drop in normal stress. We also interpret that stick slip took place within a traveling slip pulse, and we suggest that the dynamic stress drop within the slipping patch exceeded the overall static stress drop by a factor of at least 5 within a few millimeters of the fault. Our experiments did not resolve whether the fault surfaces actually separate or if fault-normal stress is just greatly reduced. In either case the net result is that fault slip is permitted to take place with much less frictional resistance than that expected from the applied load. Our observations provide laboratory evidence that fault-normal vibrations may play an important role in sustaining a rupture by facilitating the propagation of a transient instability. Faults may appear weak in part because they are dynamically weakened as they slip during rupture while retaining their strength during the interseismic period. {copyright} 1998 American Geophysical Union
ISSN 01480227
Educational Use Research
Learning Resource Type Article
Publisher Date 1998-12-01
Publisher Department Sandia National Laboratory
Publisher Place United States
Journal Journal of Geophysical Research
Volume Number 103
Issue Number B12
Organization Sandia National Laboratory


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